Programs & Examples On #Validation

Validation is used to check data to make sure it fits whatever required specifications are set for it. Typically Validation is used in checking input data, and in verifying data before storage.

MVC Return Partial View as JSON

You can extract the html string from the PartialViewResult object, similar to the answer to this thread:

Render a view as a string

PartialViewResult and ViewResult both derive from ViewResultBase, so the same method should work on both.

Using the code from the thread above, you would be able to use:

public ActionResult ReturnSpecialJsonIfInvalid(AwesomenessModel model)
    if (ModelState.IsValid)
            return PartialView("NotEvil", model);
        return View(model)
        return Json(new { error = true, message = RenderViewToString(PartialView("Evil", model))});
    return View(model);

Form Validation With Bootstrap (jQuery)

You can get another validation on this tutorial :

They use JQuery validation.




enter image description here

And you'll get the source code there.

 <form id="registration-form" class="form-horizontal">
 <h2>Sample Registration form <small>(Fill up the forms to get register)</small></h2>
 <div class="form-control-group">
        <label class="control-label" for="name">Your Name</label>
 <div class="controls">
          <input type="text" class="input-xlarge" name="name" id="name"></div>
 <div class="form-control-group">
        <label class="control-label" for="name">User Name</label>
 <div class="controls">
          <input type="text" class="input-xlarge" name="username" id="username"></div>
 <div class="form-control-group">
        <label class="control-label" for="name">Password</label>
 <div class="controls">
          <input type="password" class="input-xlarge" name="password" id="password">

<div class="form-control-group">
            <label class="control-label" for="name"> Retype Password</label>
<div class="controls">
              <input type="password" class="input-xlarge" name="confirm_password" id="confirm_password"></div>
<div class="form-control-group">
            <label class="control-label" for="email">Email Address</label>
<div class="controls">
              <input type="text" class="input-xlarge" name="email" id="email"></div>
<div class="form-control-group">
            <label class="control-label" for="message">Your Address</label>
<div class="controls">
              <textarea class="input-xlarge" name="address" id="address" rows="3"></textarea></div>
<div class="form-control-group">
            <label class="control-label" for="message"> Please agree to our policy</label>
<div class="controls">
             <input id="agree" class="checkbox" type="checkbox" name="agree"></div>
<div class="form-actions">
            <button type="submit" class="btn btn-success btn-large">Register</button>
            <button type="reset" class="btn">Cancel</button></div>

And The JQuery :

<script src="assets/js/jquery-1.7.1.min.js"></script>

<script src="assets/js/jquery.validate.js"></script>

<script src="script.js"></script>
            addEventListener('load', prettyPrint, false);
            $('pre').addClass('prettyprint linenums');

Here is the live example of the code:

Check the full tutorial:

happy coding.

How do I Validate the File Type of a File Upload?

Well - you won't be able to do it server-side on post-back as the file will get submitted (uploaded) during the post-back.

I think you may be able to do it on the client using JavaScript. Personally, I use a third party component called radUpload by Telerik. It has a good client-side and server-side API, and it provides a progress bar for big file uploads.

I'm sure there are open source solutions available, too.

How do I remove javascript validation from my eclipse project?

Turn off the JavaScript Validator in the "Builders" config for your project:

  1. Right click your project
  2. Select Properties -> Builders
  3. Uncheck the "JavaScript Validator"

Then either restart your Eclipse or/and rename the .js to something like .js_ then back again.

Validation of radio button group using jQuery validation plugin

code for radio button -

<span class="radio inline" style="margin-right: 10px;">@Html.RadioButton("Gender", "Female",false) Female</span>
<span class="radio inline" style="margin-right: 10px;">@Html.RadioButton("Gender", "Male",false) Male</span>                                                        
<div class='GenderValidation' style="color:#ee8929;"></div>    

<input class="btn btn-primary" type="submit" value="Create" id="create"/>

and jQuery code-

    $(document).ready(function () {

            var gender=$('#Gender').val();
            if ($("#Gender:checked").length == 0){
                $('.GenderValidation').text("Gender is required.");
                return false;

Allow only numbers and dot in script

This works best for me.

I also apply a currency formatter on blur where the decimal part is rounded at 2 digits just in case after validating with parseFloat.

The functions that get and set the cursor position are from Vishal Monpara's blog. I also do some nice stuff on focus with those functions. You can easily remove 2 blocks of code where 2 decimals are forced if you want and get rid of the set/get caret functions.

<input type="text" size="30" maxlength="30" onkeypress="return numericValidation(this,event);" />
<script language="JavaScript">
    function numericValidation(obj,evt) {
        var e = event || evt; // for trans-browser compatibility

        var charCode = e.which || e.keyCode;        

        if (charCode == 46) { //one dot
            if (obj.value.indexOf(".") > -1)
                return false;
            else {
                //---if the dot is positioned in the middle give the user a surprise, remember: just 2 decimals allowed
                var idx = doGetCaretPosition(obj);
                var part1 = obj.value.substr(0,idx),
                    part2 = obj.value.substring(idx);

                if (part2.length > 2) {
                    obj.value = part1 + "." + part2.substr(0,2);
                    setCaretPosition(obj, idx + 1);
                    return false;

                //allow one dot if not cheating
                return true;
        else if (charCode > 31 && (charCode < 48 || charCode > 57)) { //just numbers
            return false;

        //---just 2 decimals stubborn!
        var arr = obj.value.split(".") , pos = doGetCaretPosition(obj);

        if (arr.length == 2 && pos > arr[0].length && arr[1].length == 2)                               
            return false;

        //ok it's a number
        return true;

    function doGetCaretPosition (ctrl) {
        var CaretPos = 0;   // IE Support
        if (document.selection) {
        ctrl.focus ();
            var Sel = document.selection.createRange ();
            Sel.moveStart ('character', -ctrl.value.length);
            CaretPos = Sel.text.length;
        // Firefox support
        else if (ctrl.selectionStart || ctrl.selectionStart == '0')
            CaretPos = ctrl.selectionStart;
        return (CaretPos);

    function setCaretPosition(ctrl, pos){
        else if (ctrl.createTextRange) {
            var range = ctrl.createTextRange();
            range.moveEnd('character', pos);
            range.moveStart('character', pos);

Simple JavaScript Checkbox Validation

Another Simple way is to create & invoke the function validate() when the form loads & when submit button is clicked. By using checked property we check whether the checkbox is selected or not. cbox[0] has an index 0 which is used to access the first value (i.e Male) with name="gender"

You can do the following:

function validate() {_x000D_
  var cbox = document.forms["myForm"]["gender"];_x000D_
  if (_x000D_
    cbox[0].checked == false &&_x000D_
    cbox[1].checked == false &&_x000D_
    cbox[2].checked == false_x000D_
  ) {_x000D_
    alert("Please Select Gender");_x000D_
    return false;_x000D_
  } else {_x000D_
    alert("Successfully Submited");_x000D_
    return true;_x000D_
<form onload="return validate()" name="myForm">_x000D_
  <input type="checkbox" name="gender" value="male"> Male_x000D_
  <input type="checkbox" name="gender" value="female"> Female_x000D_
  <input type="checkbox" name="gender" value="other"> Other <br>_x000D_
  <input type="submit" name="submit" value="Submit" onclick="validate()">_x000D_

Demo: CodePen

JS jQuery - check if value is in array

The Array.prototype property represents the prototype for the Array constructor and allows you to add new properties and methods to all Array objects. we can create a prototype for this purpose

Array.prototype.has_element = function(element) {
    return $.inArray( element, this) !== -1;

And then use it like this

var numbers= [1, 2, 3, 4];
numbers.has_element(3) => true
numbers.has_element(10) => false

See the Demo below

Array.prototype.has_element = function(element) {_x000D_
  return $.inArray(element, this) !== -1;_x000D_
var numbers = [1, 2, 3, 4];_x000D_
<script src=""></script>

How to get old Value with onchange() event in text box

A dirty trick I somtimes use, is hiding variables in the 'name' attribute (that I normally don't use for other purposes):

select onFocus=( onChange=someFunction(,this.value)><option...

Somewhat unexpectedly, both the old and the new value is then submitted to someFunction(oldValue,newValue)

jQuery Form Validation before Ajax submit

This specific example will just check for inputs but you could tweak it however, Add something like this to your .ajax function:

beforeSend: function() {                    
    $empty = $('form#yourForm').find("input").filter(function() {
        return this.value === "";
    if($empty.length) {
        alert('You must fill out all fields in order to submit a change');
        return false;
        return true;

AngularJS: How do I manually set input to $valid in controller?

You cannot directly change a form's validity. If all the descendant inputs are valid, the form is valid, if not, then it is not.

What you should do is to set the validity of the input element. Like so;

addItem.capabilities.$setValidity("youAreFat", false);

Now the input (and so the form) is invalid. You can also see which error causes invalidation.

addItem.capabilities.errors.youAreFat == true;

Validate phone number using javascript

/^1?\s?(\([0-9]{3}\)[- ]?|[0-9]{3}[- ]?)[0-9]{3}[- ]?[0-9]{4}$/

This will validate all US style numbers, with or without the 1, and with or without parenthesis on area code(but if used, used properly. I.E. (902-455-4555 will not work since there is no closing parenthesis. it also allows for either - or a space between sets if wanted.) It will work for the examples provided by op.

Remove values from select list based on condition

You may use:

if ( frm.product.value=="F" ){
    var $select_box = $('[name=val]');

Update: If you modify your select box a bit to this

<select name="val" size="1" >
  <option id="A" value="A">Apple</option>
  <option id="C" value="C">Cars</option>
  <option id="H" value="H">Honda</option>
  <option id="F" value="F">Fiat</option>
  <option id="I" value="I">Indigo</option>                    

the non-jQuery solution would be this

if ( frm.product.value=="F" ){
    var elem = document.getElementById('A');
    var elem = document.getElementById('C');

Do I really need to encode '&' as '&amp;'?

If the user passes it to you, or it will wind up in a URL, you need to escape it.

If it appears in static text on a page? All browsers will get this one right either way, you don't worry much about it, since it will work.

Validate select box

if (select == "") {
    alert("Please select a selection");
    return false;

That should work for you. It just did for me.

Email Address Validation for ASP.NET

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Globalization;
using System.Text.RegularExpressions;

/// <summary>
/// Summary description for RegexUtilities
/// </summary>
public class RegexUtilities
    bool InValid = false;

    public bool IsValidEmail(string strIn)
        InValid = false;
        if (String.IsNullOrEmpty(strIn))
            return false;

        // Use IdnMapping class to convert Unicode domain names.
        strIn = Regex.Replace(strIn, @"(@)(.+)$", this.DomainMapper);
        if (InValid)
            return false;

        // Return true if strIn is in valid e-mail format. 
        return Regex.IsMatch(strIn, @"^(?("")(""[^""]+?""@)|(([0-9a-z]((\.(?!\.))|[-!#\$%&'\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-z])@))" + @"(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-z][-\w]*[0-9a-z]*\.)+[a-z0-9]{2,17}))$",

    private string DomainMapper(Match match)
        // IdnMapping class with default property values.
        IdnMapping idn = new IdnMapping();

        string domainName = match.Groups[2].Value;
            domainName = idn.GetAscii(domainName);
        catch (ArgumentException)
            InValid = true;
        return match.Groups[1].Value + domainName;


RegexUtilities EmailRegex = new RegexUtilities();

       if (txtEmail.Value != "")
                    string[] SplitClients_Email = txtEmail.Value.Split(',');
                    string Send_Email, Hold_Email;
                    Send_Email = Hold_Email = "";
                    int CountEmail;/**Region For Count Total Email**/
                    CountEmail = 0;/**First Time Email Counts Zero**/
                    bool EmaiValid = false;
                    Hold_Email = SplitClients_Email[0].ToString().Trim().TrimEnd().TrimStart().ToString();
                    if (SplitClients_Email[0].ToString() != "")
                        if (EmailRegex.IsValidEmail(Hold_Email))
                            Send_Email = Hold_Email;
                            CountEmail = 1;
                            EmaiValid = true;
                            EmaiValid = false;
                    if (EmaiValid == false)
                        divStatusMsg.Style.Add("display", "");
                        divStatusMsg.Attributes.Add("class", "alert alert-danger alert-dismissable");
                        divStatusMsg.InnerText = "ERROR !!...Please Enter A Valid Email ID.";
                        txtEmail.Value = null;
                        ScriptManager.RegisterStartupScript(Page, this.GetType(), "SmoothScroll", "SmoothScroll();", true);
                        divStatusMsg.Visible = true;
                        ClientScript.RegisterStartupScript(this.GetType(), "alert", "HideLabel();", true);
                        return false;

Trying to Validate URL Using JavaScript

This is what worked for me:

function validateURL(value) {
    return /^(https?|ftp):\/\/(((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:)*@)?(((\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5]))|((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?)(:\d*)?)(\/((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)+(\/(([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)*)*)?)?(\?((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)|[\uE000-\uF8FF]|\/|\?)*)?(\#((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)|\/|\?)*)?$/i.test(value);

from there is is just a matter of calling the function to get a true or false back:


Disabling SSL Certificate Validation in Spring RestTemplate

Essentially two things you need to do are use a custom TrustStrategy that trusts all certs, and also use NoopHostnameVerifier() to disable hostname verification. Here is the code, with all the relevant imports:

import org.apache.http.conn.ssl.NoopHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.TrustStrategy;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;

public RestTemplate getRestTemplate() throws KeyStoreException, NoSuchAlgorithmException, KeyManagementException {
    TrustStrategy acceptingTrustStrategy = new TrustStrategy() {
        public boolean isTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
            return true;
    SSLContext sslContext = org.apache.http.ssl.SSLContexts.custom().loadTrustMaterial(null, acceptingTrustStrategy).build();
    SSLConnectionSocketFactory csf = new SSLConnectionSocketFactory(sslContext, new NoopHostnameVerifier());
    CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(csf).build();
    HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
    RestTemplate restTemplate = new RestTemplate(requestFactory);
    return restTemplate;

Validating input using java.util.Scanner

Here's a minimalist way to do it.

System.out.print("Please enter an integer: ");
int demoInt = scan.nextInt();

In C# check that filename is *possibly* valid (not that it exists)

Several of the System.IO.Path methods will throw exceptions if the path or filename is invalid:

  • Path.IsPathRooted()
  • Path.GetFileName()

What is a regular expression which will match a valid domain name without a subdomain?

Here is complete code with example:

function is_domain($url)
    $parse = parse_url($url);
    if (isset($parse['host'])) {
        $domain = $parse['host'];
    } else {
        $domain = $url;

    return preg_match('/^(?!\-)(?:[a-zA-Z\d\-]{0,62}[a-zA-Z\d]\.){1,126}(?!\d+)[a-zA-Z\d]{1,63}$/', $domain);

echo is_domain(''); //true
echo is_domain(''); //true
echo is_domain(''); //false
echo is_domain('https://localhost'); //false

Validate date in dd/mm/yyyy format using JQuery Validate

This validates dd/mm/yyy dates. Edit your jquery.validate.js and add these.

Reference(Regex): Regex to validate date format dd/mm/yyyy

dateBR: function( value, element ) {
    return this.optional(element) || /^(?:(?:31(\/|-|\.)(?:0?[13578]|1[02]))\1|(?:(?:29|30)(\/|-|\.)(?:0?[1,3-9]|1[0-2])\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:29(\/|-|\.)0?2\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$|^(?:0?[1-9]|1\d|2[0-8])(\/|-|\.)(?:(?:0?[1-9])|(?:1[0-2]))\4(?:(?:1[6-9]|[2-9]\d)?\d{2})$/.test(value);

messages: {
    dateBR: "Invalid date."

classRuleSettings: {
    dateBR: {dateBR: true}


$( "#myForm" ).validate({
    rules: {
        field: {
            dateBR: true

No grammar constraints (DTD or XML schema) detected for the document

Here's the working solution for this problem:

Step 1: Right click on project and go to properties

Step 2: Go to 'libraries' and remove the project's ' JRE system library'

Step 3: Click on 'Add library'-->'JRE System Library' -->select 'Workspace default JRE'

Step 3: Go to 'Order and Export' and mark the newly added ' JRE system library'

Step 4: Refresh and Clean the project

Eureka! It's working :)

What is the minimum length of a valid international phone number?

The minimum length is 4 for Saint Helena (Format: +290 XXXX) and Niue (Format: +683 XXXX).

Validating Phone Numbers Using Javascript

Having seen simply too many edge cases, I went for a simpler check:

^(([0-9\ \+\_\-\,\.\^\*\?\$\^\#\(\)])|(ext|x)){1,20}$

The first thing one may point out is allowing repetition of "ext", but the purpose of this regex is to prevent users from accidentally entering email ids etc. instead of phone numbers, which it does.

Validating email addresses using jQuery and regex

you can use this function

 var validateEmail = function (email) {

        var pattern = /^([a-z\d!#$%&'*+\-\/=?^_`{|}~\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]+(\.[a-z\d!#$%&'*+\-\/=?^_`{|}~\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]+)*|"((([ \t]*\r\n)?[ \t]+)?([\x01-\x08\x0b\x0c\x0e-\x1f\x7f\x21\x23-\x5b\x5d-\x7e\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]|\\[\x01-\x09\x0b\x0c\x0d-\x7f\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))*(([ \t]*\r\n)?[ \t]+)?")@(([a-z\d\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]|[a-z\d\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF][a-z\d\-._~\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]*[a-z\d\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])\.)+([a-z\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]|[a-z\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF][a-z\d\-._~\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]*[a-z\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])\.?$/i;

        if (pattern.test(email)) {
            return true;
        else {
            return false;

Phone number validation Android

you can also check validation of phone number as

     * Validation of Phone Number
    public final static boolean isValidPhoneNumber(CharSequence target) {
        if (target == null || target.length() < 6 || target.length() > 13) {
            return false;
        } else {
            return android.util.Patterns.PHONE.matcher(target).matches();


ASP.NET email validator regex

Apart from the client side validation with a Validator, I also recommend doing server side validation as well.

bool isValidEmail(string input)
        var email = new System.Net.Mail.MailAddress(input);
        return true;
        return false;

CodeIgniter - File upload required validation

  1. set a rule to check the file name (if the form is multipart)

    $this->form_validation->set_rules('upload_file[name]', 'Upload file', 'required', 'No upload image :(');

  2. overwrite the $_POST array as follows:

    $_POST['upload_file'] = $_FILES['upload_file']

  3. and then do:


How to Call a JS function using OnClick event

You could use addEventListener to add as many listeners as you want.

  document.getElementById("Save").addEventListener('click',function ()
     //validation code to see State field is mandatory.  
    }  ); 

Also add script tag after the element to make sure Save element is loaded at the time when script runs

Rather than moving script tag you could call it when dom is loaded. Then you should place your code inside the

document.addEventListener('DOMContentLoaded', function() {
    document.getElementById("Save").addEventListener('click',function ()
     //validation code to see State field is mandatory.  
    }  ); 


How to check for a valid URL in Java?

I didn't like any of the implementations (because they use a Regex which is an expensive operation, or a library which is an overkill if you only need one method), so I ended up using the class with some extra checks, and limiting the protocols to: http, https, file, ftp, mailto, news, urn.

And yes, catching exceptions can be an expensive operation, but probably not as bad as Regular Expressions:

final static Set<String> protocols, protocolsWithHost;

static {
  protocolsWithHost = new HashSet<String>( 
      Arrays.asList( new String[]{ "file", "ftp", "http", "https" } ) 
  protocols = new HashSet<String>( 
      Arrays.asList( new String[]{ "mailto", "news", "urn" } ) 

public static boolean isURI(String str) {
  int colon = str.indexOf(':');
  if (colon < 3)                      return false;

  String proto = str.substring(0, colon).toLowerCase();
  if (!protocols.contains(proto))     return false;

  try {
    URI uri = new URI(str);
    if (protocolsWithHost.contains(proto)) {
      if (uri.getHost() == null)      return false;

      String path = uri.getPath();
      if (path != null) {
        for (int i=path.length()-1; i >= 0; i--) {
          if ("?<>:*|\"".indexOf( path.charAt(i) ) > -1)
            return false;

    return true;
  } catch ( Exception ex ) {}

  return false;

Spring MVC: How to perform validation?

If you have same error handling logic for different method handlers, then you would end up with lots of handlers with following code pattern:

if (validation.hasErrors()) {
  // do error handling
else {
  // do the actual business logic

Suppose you're creating RESTful services and want to return 400 Bad Request along with error messages for every validation error case. Then, the error handling part would be same for every single REST endpoint that requires validation. Repeating that very same logic in every single handler is not so DRYish!

One way to solve this problem is to drop the immediate BindingResult after each To-Be-Validated bean. Now, your handler would be like this:

public Something doStuff(@Valid Somebean bean) { 
    // do the actual business logic
    // Just the else part!

This way, if the bound bean was not valid, a MethodArgumentNotValidException will be thrown by Spring. You can define a ControllerAdvice that handles this exception with that same error handling logic:

public class ErrorHandlingControllerAdvice {
    public SomeErrorBean handleValidationError(MethodArgumentNotValidException ex) {
        // do error handling
        // Just the if part!

You still can examine the underlying BindingResult using getBindingResult method of MethodArgumentNotValidException.

HTML5 phone number validation with pattern

enter image description here


  • Minimum digits 10
  • Maximum digits 10
  • number starts with 7,8,9

How can I check if some text exist or not in the page using Selenium?

With XPath, it's not that hard. Simply search for all elements containing the given text:

List<WebElement> list = driver.findElements(By.xpath("//*[contains(text(),'" + text + "')]"));
Assert.assertTrue("Text not found!", list.size() > 0);

The official documentation is not very supportive with tasks like this, but it is the basic tool nonetheless.

The JavaDocs are greater, but it takes some time to get through everything useful and unuseful.

To learn XPath, just follow the internet. The spec is also a surprisingly good read.


Or, if you don't want your Implicit Wait to make the above code wait for the text to appear, you can do something in the way of this:

String bodyText = driver.findElement(By.tagName("body")).getText();
Assert.assertTrue("Text not found!", bodyText.contains(text));

HTML5 validation when the input type is not "submit"

2019 update: Reporting validation errors is now made easier than a the time of the accepted answer by the use of HTMLFormElement.reportValidity() which not only checks validity like checkValidity() but also reports validation errors to the user.

The HTMLFormElement.reportValidity() method returns true if the element's child controls satisfy their validation constraints. When false is returned, cancelable invalid events are fired for each invalid child and validation problems are reported to the user.

Updated solution snippet:

function submitform() {
  var f = document.getElementsByTagName('form')[0];
  if(f.reportValidity()) {

How do you do dynamic / dependent drop downs in Google Sheets?

Continuing the evolution of this solution I've upped the ante by adding support for multiple root selections and deeper nested selections. This is a further development of JavierCane's solution (which in turn built on tarheel's).

 * "on edit" event handler_x000D_
 * Based on JavierCane's answer in _x000D_
 * _x000D_
 * Each set of options has it own sheet named after the option. The _x000D_
 * values in this sheet are used to populate the drop-down._x000D_
 * The top row is assumed to be a header._x000D_
 * The sub-category column is assumed to be the next column to the right._x000D_
 * If there are no sub-categories the next column along is cleared in _x000D_
 * case the previous selection did have options._x000D_
function onEdit() {_x000D_
  var NESTED_SELECTS_SHEET_NAME = "Sitemap"_x000D_
  var activeSpreadsheet = SpreadsheetApp.getActiveSpreadsheet()_x000D_
  var activeSheet = SpreadsheetApp.getActiveSheet()_x000D_
  if (activeSheet.getName() !== NESTED_SELECTS_SHEET_NAME) {_x000D_
    // Not in the sheet with nested selects, exit!_x000D_
  var activeCell = SpreadsheetApp.getActiveRange()_x000D_
  // Top row is the header_x000D_
  if (activeCell.getColumn() > SUB_CATEGORY_COLUMN || _x000D_
      activeCell.getRow() === 1 ||_x000D_
      activeCell.getRow() > NUMBER_OF_ROOT_OPTION_CELLS + 1) {_x000D_
    // Out of selection range, exit!_x000D_
  var sheetWithActiveOptionPossibleValues = activeSpreadsheet_x000D_
    .getSheetByName(activeCell.getValue() + OPTION_POSSIBLE_VALUES_SHEET_SUFFIX)_x000D_
  if (sheetWithActiveOptionPossibleValues === null) {_x000D_
    // There are no further options for this value, so clear out any old_x000D_
    // values_x000D_
      .getRange(activeCell.getRow(), activeCell.getColumn() + 1)_x000D_
  // Get all possible values_x000D_
  var activeOptionPossibleValues = sheetWithActiveOptionPossibleValues_x000D_
    .getSheetValues(1, 1, -1, 1)_x000D_
  var possibleValuesValidation = SpreadsheetApp.newDataValidation()_x000D_
  possibleValuesValidation.requireValueInList(activeOptionPossibleValues, true)_x000D_
    .getRange(activeCell.getRow(), activeCell.getColumn() + 1)_x000D_
} // onEdit()

As Javier says:

  • Create the sheet where you'll have the nested selectors
  • Go to the "Tools" > "Script Editor…" and select the "Blank project" option
  • Paste the code attached to this answer
  • Modify the constants at the top of the script setting up your values and save it
  • Create one sheet within this same document for each possible value of the "root selector". They must be named as the value + the specified suffix.

And if you wanted to see it in action I've created a demo sheet and you can see the code if you take a copy.

javascript regex for password containing at least 8 characters, 1 number, 1 upper and 1 lowercase

Your regex only allows exactly 8 characters. Use {8,} to specify eight or more instead of {8}.

But why would you limit the allowed character range for your passwords? 8-character alphanumeric passwords can be bruteforced by my phone within minutes.

checking if number entered is a digit in jquery

Value validation wouldn't be a responsibility of jQuery. You can use pure JavaScript for this. Two ways that come to my mind are:

Number(value) == value

How to validate date with format "mm/dd/yyyy" in JavaScript?

Find in the below code which enables to perform the date validation for any of the supplied format to validate start/from and end/to dates. There could be some better approaches but have come up with this. Note supplied date format and date string go hand in hand.

<script type="text/javascript">
    function validate() {

        var format = 'yyyy-MM-dd';

        if(isAfterCurrentDate(document.getElementById('start').value, format)) {
            alert('Date is after the current date.');
        } else {
            alert('Date is not after the current date.');
        if(isBeforeCurrentDate(document.getElementById('start').value, format)) {
            alert('Date is before current date.');
        } else {
            alert('Date is not before current date.');
        if(isCurrentDate(document.getElementById('start').value, format)) {
            alert('Date is current date.');
        } else {
            alert('Date is not a current date.');
        if (isBefore(document.getElementById('start').value, document.getElementById('end').value, format)) {
            alert('Start/Effective Date cannot be greater than End/Expiration Date');
        } else {
            alert('Valid dates...');
        if (isAfter(document.getElementById('start').value, document.getElementById('end').value, format)) {
            alert('End/Expiration Date cannot be less than Start/Effective Date');
        } else {
            alert('Valid dates...');
        if (isEquals(document.getElementById('start').value, document.getElementById('end').value, format)) {
            alert('Dates are equals...');
        } else {
            alert('Dates are not equals...');
        if (isDate(document.getElementById('start').value, format)) {
            alert('Is valid date...');
        } else {
            alert('Is invalid date...');

     * This method gets the year index from the supplied format
    function getYearIndex(format) {

        var tokens = splitDateFormat(format);

        if (tokens[0] === 'YYYY'
                || tokens[0] === 'yyyy') {
            return 0;
        } else if (tokens[1]=== 'YYYY'
                || tokens[1] === 'yyyy') {
            return 1;
        } else if (tokens[2] === 'YYYY'
                || tokens[2] === 'yyyy') {
            return 2;
        // Returning the default value as -1
        return -1;

     * This method returns the year string located at the supplied index
    function getYear(date, index) {

        var tokens = splitDateFormat(date);
        return tokens[index];

     * This method gets the month index from the supplied format
    function getMonthIndex(format) {

        var tokens = splitDateFormat(format);

        if (tokens[0] === 'MM'
                || tokens[0] === 'mm') {
            return 0;
        } else if (tokens[1] === 'MM'
                || tokens[1] === 'mm') {
            return 1;
        } else if (tokens[2] === 'MM'
                || tokens[2] === 'mm') {
            return 2;
        // Returning the default value as -1
        return -1;

     * This method returns the month string located at the supplied index
    function getMonth(date, index) {

        var tokens = splitDateFormat(date);
        return tokens[index];

     * This method gets the date index from the supplied format
    function getDateIndex(format) {

        var tokens = splitDateFormat(format);

        if (tokens[0] === 'DD'
                || tokens[0] === 'dd') {
            return 0;
        } else if (tokens[1] === 'DD'
                || tokens[1] === 'dd') {
            return 1;
        } else if (tokens[2] === 'DD'
                || tokens[2] === 'dd') {
            return 2;
        // Returning the default value as -1
        return -1;

     * This method returns the date string located at the supplied index
    function getDate(date, index) {

        var tokens = splitDateFormat(date);
        return tokens[index];

     * This method returns true if date1 is before date2 else return false
    function isBefore(date1, date2, format) {
        // Validating if date1 date is greater than the date2 date
        if (new Date(getYear(date1, getYearIndex(format)), 
                getMonth(date1, getMonthIndex(format)) - 1, 
                getDate(date1, getDateIndex(format))).getTime()
            > new Date(getYear(date2, getYearIndex(format)), 
                getMonth(date2, getMonthIndex(format)) - 1, 
                getDate(date2, getDateIndex(format))).getTime()) {
            return true;
        return false;                

     * This method returns true if date1 is after date2 else return false
    function isAfter(date1, date2, format) {
        // Validating if date2 date is less than the date1 date
        if (new Date(getYear(date2, getYearIndex(format)), 
                getMonth(date2, getMonthIndex(format)) - 1, 
                getDate(date2, getDateIndex(format))).getTime()
            < new Date(getYear(date1, getYearIndex(format)), 
                getMonth(date1, getMonthIndex(format)) - 1, 
                getDate(date1, getDateIndex(format))).getTime()
            ) {
            return true;
        return false;                

     * This method returns true if date1 is equals to date2 else return false
    function isEquals(date1, date2, format) {
        // Validating if date1 date is equals to the date2 date
        if (new Date(getYear(date1, getYearIndex(format)), 
                getMonth(date1, getMonthIndex(format)) - 1, 
                getDate(date1, getDateIndex(format))).getTime()
            === new Date(getYear(date2, getYearIndex(format)), 
                getMonth(date2, getMonthIndex(format)) - 1, 
                getDate(date2, getDateIndex(format))).getTime()) {
            return true;
        return false;

     * This method validates and returns true if the supplied date is 
     * equals to the current date.
    function isCurrentDate(date, format) {
        // Validating if the supplied date is the current date
        if (new Date(getYear(date, getYearIndex(format)), 
                getMonth(date, getMonthIndex(format)) - 1, 
                getDate(date, getDateIndex(format))).getTime()
            === new Date(new Date().getFullYear(), 
                    new Date().getMonth(), 
                    new Date().getDate()).getTime()) {
            return true;
        return false;                

     * This method validates and returns true if the supplied date value 
     * is before the current date.
    function isBeforeCurrentDate(date, format) {
        // Validating if the supplied date is before the current date
        if (new Date(getYear(date, getYearIndex(format)), 
                getMonth(date, getMonthIndex(format)) - 1, 
                getDate(date, getDateIndex(format))).getTime()
            < new Date(new Date().getFullYear(), 
                    new Date().getMonth(), 
                    new Date().getDate()).getTime()) {
            return true;
        return false;                

     * This method validates and returns true if the supplied date value 
     * is after the current date.
    function isAfterCurrentDate(date, format) {
        // Validating if the supplied date is before the current date
        if (new Date(getYear(date, getYearIndex(format)), 
                getMonth(date, getMonthIndex(format)) - 1, 
                getDate(date, getDateIndex(format))).getTime()
            > new Date(new Date().getFullYear(),
                    new Date().getMonth(), 
                    new Date().getDate()).getTime()) {
            return true;
        return false;                

     * This method splits the supplied date OR format based 
     * on non alpha numeric characters in the supplied string.
    function splitDateFormat(dateFormat) {
        // Spliting the supplied string based on non characters
        return dateFormat.split(/\W/);

     * This method validates if the supplied value is a valid date.
    function isDate(date, format) {                
        // Validating if the supplied date string is valid and not a NaN (Not a Number)
        if (!isNaN(new Date(getYear(date, getYearIndex(format)), 
                getMonth(date, getMonthIndex(format)) - 1, 
                getDate(date, getDateIndex(format))))) {                    
            return true;
        return false;                                      

Below is the HTML snippet

<input type="text" name="start" id="start" size="10" value="" />
<input type="text" name="end" id="end" size="10" value="" />
<input type="button" value="Submit" onclick="javascript:validate();" />

How can I change or remove HTML5 form validation default error messages?

To set custom error message for HTML 5 validation use,

oninvalid="this.setCustomValidity('Your custom message goes here.')"

and to remove this message when user enters valid data use,


Hope this works for you. Enjoy ;)

HTML5 form validation pattern alphanumeric with spaces?

To avoid an input with only spaces, use: "[a-zA-Z0-9]+[a-zA-Z0-9 ]+".

eg: abc | abc aBc | abc 123 AbC 938234

To ensure, for example, that a first AND last name are entered, use a slight variation like

"[a-zA-Z]+[ ][a-zA-Z]+"

eg: abc def

Javascript validation: Block special characters

I think checking keypress events is not completely adequate, as I believe users can copy/paste into input boxes without triggering a keypress.

So onblur is probably somewhat more reliable (but is less immediate).

To truly make sure characters you don't want are not entered into input boxes (or textareas, etc.), I think you will need to

  1. check keypress (if you want to give immediate feedback) and
  2. also check onblur,
  3. as well as validating inputs on the server (which is the only real way to make sure nothing unwanted gets into your data).

The code samples in the other answers will work fine for doing the client-side checks (just don't rely only on checking keypress events), but as was pointed out in the accepted answer, a server-side check is really required.

Check that a input to UITextField is numeric only

I wanted a text field that only allowed integers. Here's what I ended up with (using info from here and elsewhere):

Create integer number formatter (in UIApplicationDelegate so it can be reused):

@property (nonatomic, retain) NSNumberFormatter *integerNumberFormatter;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    // Create and configure an NSNumberFormatter for integers
    integerNumberFormatter = [[NSNumberFormatter alloc] init];
    [integerNumberFormatter setMaximumFractionDigits:0];

    return YES;

Use filter in UITextFieldDelegate:

@interface MyTableViewController : UITableViewController <UITextFieldDelegate> {
    ictAppDelegate *appDelegate;

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    // Make sure the proposed string is a number
    NSNumberFormatter *inf = [appDelegate integerNumberFormatter];
    NSString* proposedString = [textField.text stringByReplacingCharactersInRange:range withString:string];
    NSNumber *proposedNumber = [inf numberFromString:proposedString];
    if (proposedNumber) {
        // Make sure the proposed number is an integer
        NSString *integerString = [inf stringFromNumber:proposedNumber];
        if ([integerString isEqualToString:proposedString]) {
            // proposed string is an integer
            return YES;

    // Warn the user we're rejecting the change
    return NO;

Javascript: how to validate dates in format MM-DD-YYYY?

I use this regex for validating MM-DD-YYYY:

function isValidDate(subject){
  if (subject.match(/^(?:(0[1-9]|1[012])[\- \/.](0[1-9]|[12][0-9]|3[01])[\- \/.](19|20)[0-9]{2})$/)){
    return true;
    return false;

It will match only valid months and you can use / - or . as separators.

MaxLength Attribute not generating client-side validation attributes

I tried this for all the inputs in my html document(textarea,inputs,etc) that had the data-val-length-max property and it works correctly.

$(document).ready(function () {
    $(":input[data-val-length-max]").each(function (index, element) {
        var length = parseInt($(this).attr("data-val-length-max"));
        $(this).prop("maxlength", length);

jQuery add required to input fields



Javascript Date Validation ( DD/MM/YYYY) & Age Checking

I suggest using moment.js which provides an easy to use method for doing this.

interactive demo

function validate(date){
    var eighteenYearsAgo = moment().subtract(18, "years");
    var birthday = moment(date);

    if (!birthday.isValid()) {
        return "invalid date";    
    else if (eighteenYearsAgo.isAfter(birthday)) {
        return "okay, you're good";    
    else {
        return "sorry, no";    

To include moment in your page, you can use CDNJS:

<script src="//"></script>

Implement Validation for WPF TextBoxes

You can additionally implement IDataErrorInfo as follows in the view model. If you implement IDataErrorInfo, you can do the validation in that instead of the setter of a particular property, then whenever there is a error, return an error message so that the text box which has the error gets a red box around it, indicating an error.

class ViewModel : INotifyPropertyChanged, IDataErrorInfo
    private string m_Name = "Type Here";
    public ViewModel()

    public string Name
            return m_Name;
            if (m_Name != value)
                m_Name = value;

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string propertyName)
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

    public string Error
        get { return "...."; }

    /// <summary>
    /// Will be called for each and every property when ever its value is changed
    /// </summary>
    /// <param name="columnName">Name of the property whose value is changed</param>
    /// <returns></returns>
    public string this[string columnName]
            return Validate(columnName);

    private string Validate(string propertyName)
        // Return error message if there is error on else return empty or null string
        string validationMessage = string.Empty;
        switch (propertyName)
            case "Name": // property name
                // TODO: Check validiation condition
                validationMessage = "Error";

        return validationMessage;

And you have to set ValidatesOnDataErrors=True in the XAML in order to invoke the methods of IDataErrorInfo as follows:

<TextBox Text="{Binding Name, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" />

Regex date validation for yyyy-mm-dd

A simple one would be


Regular expression visualization

Debuggex Demo

but this does not restrict month to 1-12 and days from 1 to 31.

There are more complex checks like in the other answers, by the way pretty clever ones. Nevertheless you have to check for a valid date, because there are no checks for if a month has 28, 30, or 31 days.

How to validate an email address in JavaScript

If you want something a human can read and maintain, I would recommend Masala Parser (I'm one of the creators of it).

import {C,Streams} from '@masala/parser'

const illegalCharset = ' @\u00A0\n\t';
const extendedIllegalCharset = illegalCharset + '.';

// Assume '[email protected]'
export function simpleEmail() {

    return C.charNotIn(illegalCharset).rep() // 'nicolas'
        .then(subDns())  //''
        .then(C.charNotIn(extendedIllegalCharset).rep()) //'uk'
        .eos(); // Must be end of the char stream

// [email protected] => extract ''
function  subDns() {
    return C.charNotIn(extendedIllegalCharset).rep().then(C.char('.')).rep()

function validateEmail(email:string) {
    console.log(email + ': ' + (simpleEmail().parse(Streams.ofString(email)).isAccepted()));

validateEmail('[email protected]'); // True
validateEmail('nz@co.'); // False, trailing "."

If you want to accept the ultimate ugly email version, you can add in quotes in the first part:

function inQuote() {
    return C.char('"')

function allEmail() {

    return inQuote().or(C.charNotIn(illegalCharset))
        .rep() // repeat (inQuote or anyCharacter)
        .eos() // Must be end of the character stream
        // Create a structure
        .map(function (characters) { return ({ email: characters.join('') }); });

'"nicolas""love-quotes"' is officially valid, but should it be in your system?

At least with Masala, you give yourself a chance to understand it. And so for the next year, colleague.

Validating URL in Java

Use the android.webkit.URLUtil on android:


Note: It is just checking the initial scheme of URL, not that the entire URL is valid.

What's the longest possible worldwide phone number I should consider in SQL varchar(length) for phone

As for "phone numbers" you should really consider the difference between a "subscriber number" and a "dialling number" and the possible formatting options of them.

A subscriber number is generally defined in the national numbering plans. The question itself shows a relation to a national view by mentioning "area code" which a lot of nations don't have. ITU has assembled an overview of the world's numbering plans publishing recommendation E.164 where the national number was found to have a maximum of 12 digits. With international direct distance calling (DDD) defined by a country code of 1 to 3 digits they added that up to 15 digits ... without formatting.

The dialling number is a different thing as there are network elements that can interpret exta values in a phone number. You may think of an answering machine and a number code that sets the call diversion parameters. As it may contain another subscriber number it must be obviously longer than its base value. RFC 4715 has set aside 20 bcd-encoded bytes for "subaddressing".

If you turn to the technical limitation then it gets even more as the subscriber number has a technical limit in the 10 bcd-encoded bytes in the 3GPP standards (like GSM) and ISDN standards (like DSS1). They have a seperate TON/NPI byte for the prefix (type of number / number plan indicator) which E.164 recommends to be written with a "+" but many number plans define it with up to 4 numbers to be dialled.

So if you want to be future proof (and many software systems run unexpectingly for a few decades) you would need to consider 24 digits for a subscriber number and 64 digits for a dialling number as the limit ... without formatting. Adding formatting may add roughly an extra character for every digit. So as a final thought it may not be a good idea to limit the phone number in the database in any way and leave shorter limits to the UX designers.

How to validate an e-mail address in swift?

In Swift 4.2 and Xcode 10.1

//Email validation
func isValidEmail(email: String) -> Bool {
    let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"
    var valid = NSPredicate(format: "SELF MATCHES %@", emailRegex).evaluate(with: email)
    if valid {
        valid = !email.contains("Invalid email id")
    return valid

//Use like this....
let emailTrimmedString = emailTF.text?.trimmingCharacters(in: .whitespaces)
if isValidEmail(email: emailTrimmedString!) == false {
   SharedClass.sharedInstance.alert(view: self, title: "", message: "Please enter valid email")

If you want to use SharedClass.

//This is SharedClass
import UIKit
class SharedClass: NSObject {

static let sharedInstance = SharedClass()

//Email validation
func isValidEmail(email: String) -> Bool {
    let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"
    var valid = NSPredicate(format: "SELF MATCHES %@", emailRegex).evaluate(with: email)
    if valid {
        valid = !email.contains("Invalid email id")
    return valid

private override init() {


And call function like this....

if SharedClass.sharedInstance. isValidEmail(email: emailTrimmedString!) == false {
   SharedClass.sharedInstance.alert(view: self, title: "", message: "Please enter correct email")
   //Your code here
} else {
   //Code here

$(form).ajaxSubmit is not a function

Try ajaxsubmit library. It does ajax submition as well as validation via ajax.

Also configuration is very flexible to support any kind of UI.

Live demo available with js, css and html examples.

Best way to alphanumeric check in JavaScript

    // On keypress event call the following method
    function AlphaNumCheck(e) {
        var charCode = (e.which) ? e.which : e.keyCode;
        if (charCode == 8) return true;

        var keynum;
        var keychar;
        var charcheck = /[a-zA-Z0-9]/;
        if (window.event) // IE
            keynum = e.keyCode;
        else {
            if (e.which) // Netscape/Firefox/Opera
                keynum = e.which;
            else return true;

        keychar = String.fromCharCode(keynum);
        return charcheck.test(keychar);

Further, this article also helps to understand JavaScript alphanumeric validation.

How to check if that data already exist in the database during update (Mongoose And Express)

In addition to already posted examples, here is another approach using express-async-wrap and asynchronous functions (ES2017).


router.put('/:id/settings/profile', wrap(async function (request, response, next) {
    const username = request.body.username
    const email =
    const userWithEmail = await userService.findUserByEmail(email)
    if (userWithEmail) {
        return response.status(409).send({message: 'Email is already taken.'})
    const userWithUsername = await userService.findUserByUsername(username)
    if (userWithUsername) {
        return response.status(409).send({message: 'Username is already taken.'})
    const user = await userService.updateProfileSettings(userId, username, email)
    return response.status(200).json({user: user})


async function updateProfileSettings (userId, username, email) {
    try {
        return User.findOneAndUpdate({'_id': userId}, {
            $set: {
                'username': username,
                '': email
        }, {new: true})
    } catch (error) {
        throw new Error(`Unable to update user with id "${userId}".`)

async function findUserByEmail (email) {
    try {
        return User.findOne({'': email.toLowerCase()})
    } catch (error) {
        throw new Error(`Unable to connect to the database.`)

async function findUserByUsername (username) {
    try {
        return User.findOne({'username': username})
    } catch (error) {
        throw new Error(`Unable to connect to the database.`)

// other methods

export default {


async function



Reactjs - Form input validation

Might be late to answer - if you don't want to modify your current code a lot and still be able to have similar validation code all over your project, you may try this one too -

Disable validation of HTML5 form elements

I found a solution for Chrome with CSS this following selector without bypassing the native verification form which could be very useful.

form input::-webkit-validation-bubble-message, 
form select::-webkit-validation-bubble-message,
form textarea::-webkit-validation-bubble-message {

By this way, you can also customise your message...

I got the solution on this page :

A non well formed numeric value encountered

You need to set the time zone using date_default_timezone_set().

How to properly validate input values with React.JS?

Use onChange={this.handleChange.bind(this, "name") method and value={this.state.fields["name"]} on input text field and below that create span element to show error, see the below example.

export default class Form extends Component {

    this.state ={
       fields: {
         email: '',
         message: ''
       errors: {},
       disabled : false

       let fields = this.state.fields;
       let errors = {};
       let formIsValid = true;

          formIsValid = false;
          errors["name"] = "Name field cannot be empty";

       if(typeof fields["name"] !== "undefined" && !fields["name"] === false){
             formIsValid = false;
             errors["name"] = "Only letters";

          formIsValid = false;
          errors["email"] = "Email field cannot be empty";

       if(typeof fields["email"] !== "undefined" && !fields["email"] === false){
          let lastAtPos = fields["email"].lastIndexOf('@');
          let lastDotPos = fields["email"].lastIndexOf('.');

          if (!(lastAtPos < lastDotPos && lastAtPos > 0 && fields["email"].indexOf('@@') === -1 && lastDotPos > 2 && (fields["email"].length - lastDotPos) > 2)) {
             formIsValid = false;
             errors["email"] = "Email is not valid";

         formIsValid = false;
         errors["message"] = " Message field cannot be empty";

      this.setState({errors: errors});
      return formIsValid;

  handleChange(field, e){
      let fields = this.state.fields;
      fields[field] =;

          console.log('validation successful')
          console.log('validation failed')

    return (
      <form onSubmit={this.handleSubmit.bind(this)} method="POST">
          <div className="row">
            <div className="col-25">
                <label htmlFor="name">Name</label>
            <div className="col-75">
                <input type="text" placeholder="Enter Name"  refs="name" onChange={this.handleChange.bind(this, "name")} value={this.state.fields["name"]}/>
                <span style={{color: "red"}}>{this.state.errors["name"]}</span>
          <div className="row">
            <div className="col-25">
              <label htmlFor="exampleInputEmail1">Email address</label>
            <div className="col-75">
                <input type="email" placeholder="Enter Email" refs="email" aria-describedby="emailHelp" onChange={this.handleChange.bind(this, "email")} value={this.state.fields["email"]}/>
                <span style={{color: "red"}}>{this.state.errors["email"]}</span>
          <div className="row">
            <div className="col-25">
                <label htmlFor="message">Message</label>
            <div className="col-75">
                <textarea type="text" placeholder="Enter Message" rows="5" refs="message" onChange={this.handleChange.bind(this, "message")} value={this.state.fields["message"]}></textarea>
                <span style={{color: "red"}}>{this.state.errors["message"]}</span>
          <div className="row">
            <button type="submit" disabled={this.state.disabled}>{this.state.disabled ? 'Sending...' : 'Send'}</button>

How to use Scanner to accept only valid int as input

Use Scanner.hasNextInt():

Returns true if the next token in this scanner's input can be interpreted as an int value in the default radix using the nextInt() method. The scanner does not advance past any input.

Here's a snippet to illustrate:

Scanner sc = new Scanner(;
System.out.print("Enter number 1: ");
while (!sc.hasNextInt());
int num1 = sc.nextInt();
int num2;
System.out.print("Enter number 2: ");
do {
    while (!sc.hasNextInt());
    num2 = sc.nextInt();
} while (num2 < num1);
System.out.println(num1 + " " + num2);

You don't have to parseInt or worry about NumberFormatException. Note that since the hasNextXXX methods don't advance past any input, you may have to call next() if you want to skip past the "garbage", as shown above.

Related questions

Laravel Password & Password_Confirmation Validation

It should be enough to do:

$this->validate($request, [
    'password' => 'sometimes,min:6,confirmed,required_with:password_confirmed',

Make password optional, but if present requires a password_confirmation that matches, also make password required only if password_confirmed is present

Input type number "only numeric value" validation

The easiest way would be to use a library like this one and specifically you want noStrings to be true

    export class CustomValidator{   // Number only validation   
      static numeric(control: AbstractControl) {
        let val = control.value;

        const hasError = validate({val: val}, {val: {numericality: {noStrings: true}}});

        if (hasError) return null;

        return val;   

jQuery Validate Plugin - Trigger validation of single field

in case u wanna do the validation for "some elements" (not all element) on your form.You can use this method:

$('input[name="element-one"], input[name="element-two"], input[name="element-three"]').valid();

Hope it help everybody :)


Show red border for all invalid fields after submitting form angularjs

Reference article: Show red color border for invalid input fields angualrjs

I used ng-class on all input below

<input type="text" ng-class="{submitted:newEmployee.submitted}" placeholder="First Name" data-ng-model="model.firstName" id="FirstName" name="FirstName" required/>

when I click on save button I am changing newEmployee.submitted value to true(you can check it in my question). So when I click on save, a class named submitted gets added to all input fields(there are some other classes initially added by angularjs).

So now my input field contains classes like this

class="ng-pristine ng-invalid submitted"

now I am using below css code to show red border on all invalid input fields(after submitting the form)
  border:1px solid #f00;

Thank you !!


We can add the ng-class at the form element instead of applying it to all input elements. So if the form is submitted, a new class(submitted) gets added to the form element. Then we can select all the invalid input fields using the below selector

form.submitted .ng-invalid
    border:1px solid #f00;

Min/Max-value validators in mvc

Here is how I would write a validator for MaxValue

public class MaxValueAttribute : ValidationAttribute
        private readonly int _maxValue;

        public MaxValueAttribute(int maxValue)
            _maxValue = maxValue;

        public override bool IsValid(object value)
            return (int) value <= _maxValue;

The MinValue Attribute should be fairly the same

Regular expression for URL validation (in JavaScript)

Try this regex


It works best for me.

How can I test a PDF document if it is PDF/A compliant?

If you download the latest version of Adobe Acrobat Reader, it will tell you if your pdf is PDF/A compliant. Just open the PDF file and a big blue marking should appear.

OpenOffice supports PDF/A. For some reason "PDF/A-1" is called

internally in OpenOffice. Just add 1 to that value and your output should be PDF/A.

The different values can be

1 = PDFX1A2001
2 = PDFX32002
3 = PDFA1A
4 = PDFA1B

You set

to be a
HashMap('SelectPdfVersion',1) //1 for PDFX1A2001

Is div inside list allowed?

As an addendum: Before HTML 5 while a div inside a li is valid, a div inside a dl, dd, or dt is not!

How do I turn off the mysql password validation?

For mysql 8.0 the command to disable password validation component is:

UNINSTALL COMPONENT 'file://component_validate_password';

To install it back again, the command is:

INSTALL COMPONENT 'file://component_validate_password';

If you just want to change the policy of password validation plugin:

SET GLOBAL validate_password.policy = 0;   // For LOW
SET GLOBAL validate_password.policy = 1;   // For MEDIUM
SET GLOBAL validate_password.policy = 2;   // For HIGH

An invalid form control with name='' is not focusable

Alternatively another and foolproof answer is to use HTML5 Placeholder attribute then there will be no need to use any js validations.

<input id="elemID" name="elemName" placeholder="Some Placeholder Text" type="hidden" required="required">

Chrome will not be able to find any empty, hidden and required elements to focus on. Simple Solution.

Hope that helps. I am totally sorted with this solution.

Java Regex to Validate Full Name allow only Spaces and Letters

please try this regex (allow only Alphabets and space)

"[a-zA-Z][a-zA-Z ]*"

if you want it for IOS then,

NSString *yourstring = @"hello";

NSString *Regex = @"[a-zA-Z][a-zA-Z ]*";
NSPredicate *TestResult = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",Regex];

if ([TestResult evaluateWithObject:yourstring] == true)
    // validation passed
    // invalid name

php date validation

Try This


this regular expression valid for :

  • 2017-01-01T00:00:00+0000
  • 2017-01-01 00:00:00+00:00
  • 2017-01-01T00:00:00+00:00
  • 2017-01-01 00:00:00+0000
  • 2017-01-01

Remember that this will be cover all case of date and date time with (-) character

jQuery: what is the best way to restrict "number"-only input for textboxes? (allow decimal points)

This code belongs to restrict alphabets in text boxes,have to enter oly number validate on keypress event.Hope it will help for you

HTML Tags:

<input id="txtPurchaseAmnt" style="width:103px" type="text" class="txt" maxlength="5" onkeypress="return isNumberKey(event);" />

function onlyNumbers(key) {

        var keycode = (key.which) ? key.which : key.keyCode

        if ((keycode > 47 && keycode < 58) || (keycode == 46 || keycode == 8) || (keycode == 9 || keycode == 13) || (keycode == 37 || keycode == 39)) {

            return true;
        else {
            return false;

Validation of file extension before uploading file

we can check it on submit or we can make change event of that control

var fileInput = document.getElementById('file');
    var filePath = fileInput.value;
    var allowedExtensions = /(\.jpeg|\.JPEG|\.gif|\.GIF|\.png|\.PNG)$/;
    if (filePath != "" && !allowedExtensions.exec(filePath)) {
    alert('Invalid file extention pleasse select another file');
    fileInput.value = '';
    return false;

javascript how to create a validation error message without using alert

You need to stop the submission if an error occured:


<form name ="myform" onsubmit="return validation();"> 


if (document.myform.username.value == "") {
     document.getElementById('errors').innerHTML="*Please enter a username*";
     return false;

Check input value length

You can add a form onsubmit handler, something like:

<form onsubmit="return validate();">


<script>function validate() {
 // check if input is bigger than 3
 var value = document.getElementById('titleeee').value;
 if (value.length < 3) {
   return false; // keep form from submitting

 // else form is good let it submit, of course you will 
 // probably want to alert the user WHAT went wrong.

 return true;

How to validate inputs dynamically created using ng-repeat, ng-show (angular)

AngularJS relies on input names to expose validation errors.

Unfortunately, as of today, it is not possible (without using a custom directive) to dynamically generate a name of an input. Indeed, checking input docs we can see that the name attribute accepts a string only.

To solve the 'dynamic name' problem you need to create an inner form (see ng-form):

<div ng-repeat="social in formData.socials">
      <ng-form name="urlForm">
            <input type="url" name="socialUrl" ng-model="social.url">
            <span class="alert error" ng-show="urlForm.socialUrl.$error.url">URL error</span>

The other alternative would be to write a custom directive for this.

Here is the jsFiddle showing the usage of the ngForm:

jQuery validation plugin: accept only alphabetical characters?

Just a small addition to Nick's answer (which works great !) :

If you want to allow spaces in between letters, for example , you may restrict to enter only letters in full name, but it should allow space as well - just list the space as below with a comma. And in the same way if you need to allow any other specific character:

jQuery.validator.addMethod("lettersonly", function(value, element) 
return this.optional(element) || /^[a-z," "]+$/i.test(value);
}, "Letters and spaces only please");       

Min / Max Validator in Angular 2 Final

I was looking for the same thing now, used this to solve it.

My code:{
  'feild': [value,  [Validators.required, Validators.min(1)]]

C# Validating input for textbox on winforms

With WinForms you can use the ErrorProvider in conjunction with the Validating event to handle the validation of user input. The Validating event provides the hook to perform the validation and ErrorProvider gives a nice consistent approach to providing the user with feedback on any error conditions.

difference between @size(max = value ) and @min(value) @max(value)

From the documentation I get the impression that in your example it would be intended to use:

@Range(min= SEQ_MIN_VALUE, max= SEQ_MAX_VALUE)

Checks whether the annotated value lies between (inclusive) the specified minimum and maximum. Supported data types:

BigDecimal, BigInteger, CharSequence, byte, short, int, long and the respective wrappers of the primitive types

Validating with an XML schema in Python

I am assuming you mean using XSD files. Surprisingly there aren't many python XML libraries that support this. lxml does however. Check Validation with lxml. The page also lists how to use lxml to validate with other schema types.

How to validate white spaces/empty spaces? [Angular 2]

To validate white space in starting in an input you can just call change event and do inline function for that.

<input type="text" class="form-control"                     
            placeholder="First Name without white space in starting"
            (change) ="user.FirstName = user.FirstName.trim()"

Allow User to input HTML in ASP.NET MVC - ValidateInput or AllowHtml

I faced the same issue although i added [System.Web.Mvc.AllowHtml] to the concerning property as described in some answers.

In my case, i have an UnhandledExceptionFilter class that accesses the Request object before MVC validation takes place (and therefore AllowHtml has not effect) and this access raises a [HttpRequestValidationException] A potentially dangerous Request.Form value was detected from the client.

This means, accessing certain properties of a Request object implicitly fires validation (in my case its the Params property).

A solution to prevent validation is documented on MSDN

To disable request validation for a specific field in a request (for example, for an input element or query string value), call the Request.Unvalidated method when you get the item, as shown in the following example

Therefore, if you have code like this

var lParams = aRequestContext.HttpContext.Request.Params;
if (lParams.Count > 0)

change it to

var lUnvalidatedRequest = aRequestContext.HttpContext.Request.Unvalidated;

var lForm = lUnvalidatedRequest.Form;
if (lForm.Count > 0)

or just use the Form property which does not seem to fire validation

var lForm = aRequestContext.HttpContext.Request.Form;
if (lForm.Count > 0)

Email validation using jQuery

Bug is in Jquery Validation Validation Plugin Only validates with @ to change this

change the code to this

email: function( value, element ) {
    // From
    // Retrieved 2014-01-14
    // If you have a problem with this implementation, report a bug against the above spec
    // Or use custom methods to implement your own email validation
    return this.optional( element ) || /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/.test( value );

Validating parameters to a Bash script

I would use bash's [[:

if [[ ! ("$#" == 1 && $1 =~ ^[0-9]+$ && -d $1) ]]; then 
    echo 'Please pass a number that corresponds to a directory'
    exit 1

I found this faq to be a good source of information.

How to add a RequiredFieldValidator to DropDownList control?

Suppose your drop down list is:

<asp:DropDownList runat="server" id="ddl">
<asp:ListItem Value="0" text="Select a Value">

There are two ways:

<asp:RequiredFieldValidator ID="re1" runat="Server" InitialValue="0" />

the 2nd way is to use a compare validator:

<asp:CompareValidator ID="re1" runat="Server" ValueToCompare="0" ControlToCompare="ddl" Operator="Equal" />

Simplest JQuery validation rules example

    rules: {
     cname : { required : true, minlength: 2 }

Should be something like that, I've just typed this up in the editor here so might be a syntax error or two, but you should be able to follow the pattern and the documentation

jQuery validate Uncaught TypeError: Cannot read property 'nodeName' of null

I had this problem and it was because the panel was outside of the [data-role="page"] element.

rails 3 validation on uniqueness on multiple attributes

Dont work for me, need to put scope in plural

validates_uniqueness_of :teacher_id, :scopes => [:semester_id, :class_id]

JavaScript: client-side vs. server-side validation

Client side data validation can be useful for a better user experience: for example, I a user who types wrongly his email address, should not wait til his request is processed by a remote server to learn about the typo he did.

Nevertheless, as an attacker can bypass client side validation (and may even not use the browser at all), server side validation is required, and must be the real gate to protect your backend from nefarious users.

Set Value of Input Using Javascript Function

Depending on the usecase it makes a difference whether you use javascript (element.value = x) or jQuery $(element).val(x);

When x is undefined jQuery results in an empty String whereas javascript results in "undefined" as a String.

repaint() in Java

You may need to call frame.repaint() as well to force the frame to actually redraw itself. I've had issues before where I tried to repaint a component and it wasn't updating what was displayed until the parent's repaint() method was called.

How to scanf only integer and repeat reading if the user enters non-numeric characters?

#include <stdio.h>
    char str[100];
    int num;
    while(1) {
        printf("Enter a number: ");
        printf("You entered the number %d\n",num);
    return 0;

%[^0-9] in scanf() gobbles up all that is not between 0 and 9. Basically it cleans the input stream of non-digits and puts it in str. Well, the length of non-digit sequence is limited to 100. The following %d selects only integers in the input stream and places it in num.

Right HTTP status code to wrong input

409 Conflict could be an acceptable solution.

According to:

The request could not be completed due to a conflict with the current state of the resource. This code is only allowed in situations where it is expected that the user might be able to resolve the conflict and resubmit the request. The response body SHOULD include enough information for the user to recognize the source of the conflict. Ideally, the response entity would include enough information for the user or user agent to fix the problem; however, that might not be possible and is not required.

The doc continues with an example:

Conflicts are most likely to occur in response to a PUT request. For example, if versioning were being used and the entity being PUT included changes to a resource which conflict with those made by an earlier (third-party) request, the server might use the 409 response to indicate that it can't complete the request. In this case, the response entity would likely contain a list of the differences between the two versions in a format defined by the response Content-Type.

In my case, I would like to PUT a string, that must be unique, to a database via an API. Before adding it to the database, I am checking that it is not already in the database.

If it is, I will return "Error: The string is already in the database", 409.

I believe this is what the OP wanted: an error code suitable for when the data does not pass the server's criteria.

(Built-in) way in JavaScript to check if a string is a valid number

Maybe there are one or two people coming across this question who need a much stricter check than usual (like I did). In that case, this might be useful:

if(str === String(Number(str))) {
  // it's a "perfectly formatted" number

Beware! This will reject strings like .1, 40.000, 080, 00.1. It's very picky - the string must match the "most minimal perfect form" of the number for this test to pass.

It uses the String and Number constructor to cast the string to a number and back again and thus checks if the JavaScript engine's "perfect minimal form" (the one it got converted to with the initial Number constructor) matches the original string.

Get all validation errors from Angular 2 FormGroup

export class GenericValidator {
    constructor(private validationMessages: { [key: string]: { [key: string]: string } }) {

processMessages(container: FormGroup): { [key: string]: string } {
    const messages = {};
    for (const controlKey in container.controls) {
        if (container.controls.hasOwnProperty(controlKey)) {
            const c = container.controls[controlKey];
            if (c instanceof FormGroup) {
                const childMessages = this.processMessages(c);
                // handling formGroup errors messages
                const formGroupErrors = {};
                if (this.validationMessages[controlKey]) {
                    formGroupErrors[controlKey] = '';
                    if (c.errors) {
                        Object.keys(c.errors).map((messageKey) => {
                            if (this.validationMessages[controlKey][messageKey]) {
                                formGroupErrors[controlKey] += this.validationMessages[controlKey][messageKey] + ' ';
                Object.assign(messages, childMessages, formGroupErrors);
            } else {
                // handling control fields errors messages
                if (this.validationMessages[controlKey]) {
                    messages[controlKey] = '';
                    if ((c.dirty || c.touched) && c.errors) {
                        Object.keys(c.errors).map((messageKey) => {
                            if (this.validationMessages[controlKey][messageKey]) {
                                messages[controlKey] += this.validationMessages[controlKey][messageKey] + ' ';
    return messages;

I took it from Deborahk and modified it a little bit.

How to check whether a string is a valid HTTP URL?

After Uri.TryCreate you can check Uri.Scheme to see if it HTTP(s).

PHP validation/regex for URL

    function validateURL($URL) {
      $pattern_1 = "/^(http|https|ftp):\/\/(([A-Z0-9][A-Z0-9_-]*)(\.[A-Z0-9][A-Z0-9_-]*)+.(com|org|net|dk|at|us|tv|info|uk||biz|se)$)(:(\d+))?\/?/i";
      $pattern_2 = "/^(www)((\.[A-Z0-9][A-Z0-9_-]*)+.(com|org|net|dk|at|us|tv|info|uk||biz|se)$)(:(\d+))?\/?/i";       
      if(preg_match($pattern_1, $URL) || preg_match($pattern_2, $URL)){
        return true;
      } else{
        return false;

How to revert a merge commit that's already pushed to remote branch?

I also faced this issue on a PR that has been merged to the master branch of a GitHub repo.

Since I just wanted to modify some modified files but not the whole changes the PR brought, I had to amend the merge commit with git commit --am.


  1. Go to the branch which you want to change / revert some modified files
  2. Do the changes you want according to modified files
  3. run git add * or git add <file>
  4. run git commit --am and validate
  5. run git push -f

Why it's interesting:

  • It keeps the PR's author commit unchanged
  • It doesn't break the git tree
  • You'll be marked as committer (merge commit author will remain unchanged)
  • Git act as if you resolved conflicts, it will remove / change the code in modified files as if you manually tell GitHub to not merge it as-is

jQuery prevent change for select

You might need to use the ".live" option in jQuery since the behavior will be evaluated in real-time based on the condition you've set.

$('#my_select').live('change', function(ev) {
    return false;

How to delete file from public folder in laravel 5.1

First, you should go to config/filesystems.php and set 'root' => public_path() like so:

'disks' => [

    'local' => [
        'driver' => 'local',
        'root' => public_path(),

Then, you can use Storage::delete($filename);

Resizing image in Java

If you have an java.awt.Image, rezising it doesn't require any additional libraries. Just do:

Image newImage = yourImage.getScaledInstance(newWidth, newHeight, Image.SCALE_DEFAULT);

Ovbiously, replace newWidth and newHeight with the dimensions of the specified image.
Notice the last parameter: it tells to the runtime the algorithm you want to use for resizing.

There are algorithms that produce a very precise result, however these take a large time to complete.
You can use any of the following algorithms:

See the Javadoc for more info.

hexadecimal string to byte array in python

You can use the Codecs module in the Python Standard Library, i.e.

import codecs

codecs.decode(hexstring, 'hex_codec')

gnuplot : plotting data from multiple input files in a single graph


This is another way to get multiple plots at once:


Write string to text file and ensure it always overwrites the existing content.

If your code doesn't require the file to be truncated first, you can use the FileMode.OpenOrCreate to open the filestream, which will create the file if it doesn't exist or open it if it does. You can use the stream to point at the front and start overwriting the existing file?

I'm assuming your using a streams here, there are other ways to write a file.

error: (-215) !empty() in function detectMultiScale

the error may be due to, the required xml files has not been loaded properly. Search for the file haarcascade_frontalface_default.xml by using the search engine of ur OS get the full path and put it as the argument to cv2.CascadeClassifier as string

How to construct a set out of list items in python?

Here is another solution:

set(['E:\\', 'D:\\', 'C:\\'])

In this code I have used the set method in order to turn it into a set and then it removed all duplicate values from the list

How to install xgboost in Anaconda Python (Windows platform)?

This simple helped me you don't have to include anything at the end because if you include something, some of your packages will be upgraded but some will be downgraded. You can get this from this url:

conda install -c anaconda py-xgboost 

Disable Chrome strict MIME type checking

In case you are using node.js (with express)

If you want to serve static files in node.js, you need to use a function. Add the following code to your js file:


Where app is:

const express = require("express");
const app = express();

Then create a folder called public in you project folder. (You could call it something else, this is just good practice but remember to change it from the function as well.)

Then in this file create another folder named css (and/or images file under css if you want to serve static images as well.) then add your css files to this folder.

After you add them change the stylesheet accordingly. For example if it was:




Make them:


That should work

Data truncated for column?

By issuing this statement:


... you omitted the length parameter. Your query was therefore equivalent to:

ALTER TABLE calls MODIFY incoming_Cid CHAR(1);

You must specify the field size for sizes larger than 1:

ALTER TABLE calls MODIFY incoming_Cid CHAR(34);

accessing a file using [NSBundle mainBundle] pathForResource: ofType:inDirectory:

Are you attempting to do this inside of an XCTest and on the verge of smashing your laptop? This is the thread for you: Why can't code inside unit tests find bundle resources?

Android webview & localStorage

I've also had problem with data being lost after application is restarted. Adding this helped:

webView.getSettings().setDatabasePath("/data/data/" + webView.getContext().getPackageName() + "/databases/");

What does "request for member '*******' in something not a structure or union" mean?

can also appear if:

struct foo {   int x, int y, int z }foo; 


instead of

struct foo {   int x; int y; int z; }foo; 


Change UITextField and UITextView Cursor / Caret Color

With iOS7 you can simply change tintColor of the textField

How to make a div have a fixed size?

<div class="ai">a b c d e f</div> // something like ~100px
<div class="ai">a b c d e</div> // ~80
<div class="ai">a b c d</div> // ~60 


function _reWidthAll_div(classname) {

var _maxwidth = 0;


    var _width = $(this).width();

    _maxwidth = (_width >= _maxwidth) ? _width : _maxwidth; // define max width

$(classname).width(_maxwidth); // return all div same width




How to directly execute SQL query in C#?

IMPORTANT NOTE: You should not concatenate SQL queries unless you trust the user completely. Query concatenation involves risk of SQL Injection being used to take over the world, ...khem, your database.

If you don't want to go into details how to execute query using SqlCommand then you could call the same command line like this:

string userInput = "Brian";
var process = new Process();
var startInfo = new ProcessStartInfo();
startInfo.WindowStyle = ProcessWindowStyle.Hidden;
startInfo.FileName = "cmd.exe";
startInfo.Arguments = string.Format(@"sqlcmd.exe -S .\PDATA_SQLEXPRESS -U sa -P 2BeChanged! -d PDATA_SQLEXPRESS  
     -s ; -W -w 100 -Q "" SELECT tPatCulIntPatIDPk, tPatSFirstname, tPatSName,
     tPatDBirthday  FROM  [dbo].[TPatientRaw] WHERE tPatSName = '{0}' """, userInput);

process.StartInfo = startInfo;

Just ensure that you escape each double quote " with ""

Run bash command on jenkins pipeline

I'm sure that the above answers work perfectly. However, I had the difficulty of adding the double quotes as my bash lines where closer to 100. So, the following way helped me. (In a nutshell, no double quotes around each line of the shell)

Also, when I had "bash '''#!/bin/bash" within steps, I got the following error java.lang.NoSuchMethodError: No such DSL method '**bash**' found among steps

pipeline {
    agent none

    stages {

        stage ('Hello') {
            agent any

            steps {
                echo 'Hello, '

                sh '''#!/bin/bash

                    echo "Hello from bash"
                    echo "Who I'm $SHELL"

The result of the above execution is

enter image description here

Loop through an array php

foreach($array as $item=>$values){
     echo $values->filepath;

How to get the full url in Express?

var full_address = req.protocol + "://" + + req.originalUrl;


var full_address = req.protocol + "://" + + req.baseUrl;

How to check if a socket is connected/disconnected in C#?

As Paul Turner answered Socket.Connected cannot be used in this situation. You need to poll connection every time to see if connection is still active. This is code I used:

bool SocketConnected(Socket s)
    bool part1 = s.Poll(1000, SelectMode.SelectRead);
    bool part2 = (s.Available == 0);
    if (part1 && part2)
        return false;
        return true;

It works like this:

  • s.Poll returns true if
    • connection is closed, reset, terminated or pending (meaning no active connection)
    • connection is active and there is data available for reading
  • s.Available returns number of bytes available for reading
  • if both are true:
    • there is no data available to read so connection is not active

How to handle screen orientation change when progress dialog and background thread active?

These days there is a much more distinct way to handle these types of issues. The typical approach is:

1. Ensure your data is properly seperated from the UI:

Anything that is a background process should be in a retained Fragment (set this with Fragment.setRetainInstance(). This becomes your 'persistent data storage' where anything data based that you would like retained is kept. After the orientation change event, this Fragment will still be accessible in its original state through a FragmentManager.findFragmentByTag() call (when you create it you should give it a tag not an ID as it is not attached to a View).

See the Handling Runtime Changes developed guide for information about doing this correctly and why it is the best option.

2. Ensure you are interfacing correctly and safely between the background processs and your UI:

You must reverse your linking process. At the moment your background process attaches itself to a View - instead your View should be attaching itself to the background process. It makes more sense right? The View's action is dependent on the background process, whereas the background process is not dependent on the View.This means changing the link to a standard Listener interface. Say your process (whatever class it is - whether it is an AsyncTask, Runnable or whatever) defines a OnProcessFinishedListener, when the process is done it should call that listener if it exists.

This answer is a nice concise description of how to do custom listeners.

3. Link your UI into the data process whenever the UI is created (including orientation changes):

Now you must worry about interfacing the background task with whatever your current View structure is. If you are handling your orientation changes properly (not the configChanges hack people always recommend), then your Dialog will be recreated by the system. This is important, it means that on the orientation change, all your Dialog's lifecycle methods are recalled. So in any of these methods (onCreateDialog is usually a good place), you could do a call like the following:

DataFragment f = getActivity().getFragmentManager().findFragmentByTag("BACKGROUND_TAG");
if (f != null) {
    f.mBackgroundProcess.setOnProcessFinishedListener(new OnProcessFinishedListener() {
        public void onProcessFinished() {

See the Fragment lifecycle for deciding where setting the listener best fits in your individual implementation.

This is a general approach to providing a robust and complete solution to the generic problem asked in this question. There is probably a few minor pieces missing in this answer depending on your individual scenario, but this is generally the most correct approach for properly handling orientation change events.

Split and join C# string

You can use string.Split and string.Join:

string theString = "Some Very Large String Here";
var array = theString.Split(' ');
string firstElem = array.First();
string restOfArray = string.Join(" ", array.Skip(1));

If you know you always only want to split off the first element, you can use:

var array = theString.Split(' ', 2);

This makes it so you don't have to join:

string restOfArray = array[1];

How to select all instances of selected region in Sublime Text

Note: You should not edit the default settings, because they get reset on updates/upgrades. For customization, you should override any setting by using the user bindings.

On Mac:

  • Sublime Text 2 > Preferences > Key Bindings-Default
  • Sublime Text 3 > Preferences > Key Bindings

This opens a document that you can edit the keybindings for Sublime.

If you search "ctrl+super+g" you find this:

{ "keys": ["ctrl+super+g"], "command": "find_all_under" },

How to check if a std::string is set or not?

There is no "unset" state for std::string, it is always set to something.

How to check for valid email address?

Finding Email-id: finding IP screenshot

import re 
  for d in c:'[\w.]+\@[\w.]+',d)
    if obj:
#for more calcification click on image above..

Open Excel file for reading with VBA without display

The problem with both iDevlop's and Ashok's answers is that the fundamental problem is an Excel design flaw (apparently) in which the Open method fails to respect the Application.ScreenUpdating setting of False. Consequently, setting it to False is of no benefit to this problem.

If Patrick McDonald's solution is too burdensome due to the overhead of starting a second instance of Excel, then the best solution I've found is to minimize the time that the opened workbook is visible by re-activating the original window as quickly as possible:

Dim TempWkBk As Workbook
Dim CurrentWin As Window

Set CurrentWin = ActiveWindow
Set TempWkBk = Workbooks.Open(SomeFilePath)
CurrentWin.Activate      'Allows only a VERY brief flash of the opened workbook
TempWkBk.Windows(1).Visible = False 'Only necessary if you also need to prevent
                                    'the user from manually accessing the opened
                                    'workbook before it is closed.

'Operate on the new workbook, which is not visible to the user, then close it...

How do I print out the contents of an object in Rails for easy debugging?

I generally first try .inspect, if that doesn't give me what I want, I'll switch to .to_yaml.

class User
  attr_accessor :name, :age

user = = "John Smith"
user.age = 30

puts user.inspect
#=> #<User:0x423270c @name="John Smith", @age=30>
puts user.to_yaml
#=> --- !ruby/object:User
#=> age: 30
#=> name: John Smith

Hope that helps.

Convert list of ASCII codes to string (byte array) in Python

For Python 2.6 and later if you are dealing with bytes then a bytearray is the most obvious choice:

>>> str(bytearray([17, 24, 121, 1, 12, 222, 34, 76]))

To me this is even more direct than Alex Martelli's answer - still no string manipulation or len call but now you don't even need to import anything!

Reading a text file using OpenFileDialog in windows forms

for this approach, you will need to add system.IO to your references by adding the next line of code below the other references near the top of the c# file(where the other using ****.** stand).

using System.IO;

this next code contains 2 methods of reading the text, the first will read single lines and stores them in a string variable, the second one reads the whole text and saves it in a string variable(including "\n" (enters))

both should be quite easy to understand and use.

    string pathToFile = "";//to save the location of the selected object
    private void openToolStripMenuItem_Click(object sender, EventArgs e)
        OpenFileDialog theDialog = new OpenFileDialog();
        theDialog.Title = "Open Text File";
        theDialog.Filter = "TXT files|*.txt";
        theDialog.InitialDirectory = @"C:\";
        if (theDialog.ShowDialog() == DialogResult.OK)
            pathToFile = theDialog.FileName;//doesn't need .tostring because .filename returns a string// saves the location of the selected object


        if (File.Exists(pathToFile))// only executes if the file at pathtofile exists//you need to add the using System.IO reference at the top of te code to use this
            string firstLine = File.ReadAllLines(pathToFile).Skip(0).Take(1).First();//selects first line of the file
            string secondLine = File.ReadAllLines(pathToFile).Skip(1).Take(1).First();

            string text = "";
            using(StreamReader sr =new StreamReader(pathToFile))
                text = sr.ReadToEnd();//all text wil be saved in text enters are also saved

To split the text you can use .Split(" ") and use a loop to put the name back into one string. if you don't want to use .Split() then you could also use foreach and ad an if statement to split it where needed.

to add the data to your class you can use the constructor to add the data like:

  public Employee(int EMPLOYEENUM, string NAME, string ADRESS, double WAGE, double HOURS)
            EmployeeNum = EMPLOYEENUM;
            Name = NAME;
            Address = ADRESS;
            Wage = WAGE;
            Hours = HOURS;

or you can add it using the set by typing .variablename after the name of the instance(if they are public and have a set this will work). to read the data you can use the get by typing .variablename after the name of the instance(if they are public and have a get this will work).

What does it mean by command cd /d %~dp0 in Windows

Let's dissect it. There are three parts:

  1. cd -- This is change directory command.
  2. /d -- This switch makes cd change both drive and directory at once. Without it you would have to do cd %~d0 & cd %~p0. (%~d0 Changs active drive, cd %~p0 change the directory).
  3. %~dp0 -- This can be dissected further into three parts:
    1. %0 -- This represents zeroth parameter of your batch script. It expands into the name of the batch file itself.
    2. %~0 -- The ~ there strips double quotes (") around the expanded argument.
    3. %dp0 -- The d and p there are modifiers of the expansion. The d forces addition of a drive letter and the p adds full path.

Detect all changes to a <input type="text"> (immediately) using JQuery

Unfortunately there is no event or set of events that matches your criteria. Keypresses and copy/paste can both be handled with the keyup event. Changes through JS are trickier. If you have control over the code that sets the textbox, your best bet is to modify it to either call your function directly or trigger a user event on the textbox:

// Compare the textbox's current and last value.  Report a change to the console.
function watchTextbox() {
  var txtInput = $('#txtInput');
  var lastValue ='lastValue');
  var currentValue = txtInput.val();
  if (lastValue != currentValue) {
    console.log('Value changed from ' + lastValue + ' to ' + currentValue);'lastValue', currentValue);

// Record the initial value of the textbox.
$('#txtInput').data('lastValue', $('#txtInput').val());

// Bind to the keypress and user-defined set event.
$('#txtInput').bind('keypress set', null, watchTextbox);

// Example of JS code triggering the user event
$('#btnSetText').click(function (ev) {
  $('#txtInput').val('abc def').trigger('set');

If you don't have control over that code, you could use setInterval() to 'watch' the textbox for changes:

// Check the textbox every 100 milliseconds.  This seems to be pretty responsive.
setInterval(watchTextbox, 100);

This sort of active monitoring won't catch updates 'immediately', but it seems to be fast enough that there is no perceptible lag. As DrLouie pointed out in comments, this solution probably doesn't scale well if you need to watch lots of inputs. You can always adjust the 2nd parameter to setInterval() to check more or less frequently.

batch script - run command on each file in directory

for /r %%v in (*.xls) do ssconvert "%%v" "%%vx"

a couple have people have asked me to explain this, so:

Part 1: for /r %%v in (*.xls)

This part returns an array of files in the current directory that have the xls extension. The %% may look a little curious. This is basically the special % character from command line as used in %PATH% or %TEMP%. To use it in a batch file we need to escape it like so: %%PATH%% or %%TEMP%%. In this case we are simply escaping the temporary variable v, which will hold our array of filenames.

We are using the /r switch to search for files recursively, so any matching files in child folders will also be located.

Part 2: do ssconvert "%%v" "%%vx"

This second part is what will get executed once per matching filename, so if the following files were present in the current folder:

c:\temp\mySheet.xls, c:\temp\mySheet_yesterday.xls, c:\temp\mySheet_20160902.xls

the following commands would be executed:

ssconvert "c:\temp\mySheet.xls" "c:\temp\mySheet.xlsx" ssconvert "c:\temp\mySheet_yesterday.xls" "c:\temp\mySheet_yesterday.xlsx" ssconvert "c:\temp\mySheet_20160902.xls" "c:\temp\mySheet_20160902.xlsx"

How to change the hosts file on android

adb shell
mount -o rw,remount -t yaffs2 /dev/block/mtdblock3 /system

This assumes your /system is yaffs2 and that it's at /dev/block/mtdblock3 the easier/better way to do this on most Android phones is:

adb shell
mount -o remount,rw /system

Done. This just says remount /system read-write, you don't have to specify filesystem or mount location.

Using print statements only to debug

A better way to debug the code is, by using module clrprint

It prints a color full output only when pass parameter debug=True

from clrprint import *
clrprint('ERROR:', information,clr=['r','y'], debug=True)

How to get current user in core

Simple way that works and I checked.

private readonly UserManager<IdentityUser> _userManager;
public CompetitionsController(UserManager<IdentityUser> userManager)
    _userManager = userManager;

var user = await _userManager.GetUserAsync(HttpContext.User);

then you can all the properties of this variables like user.Email. I hope this would help someone.


It's an apparently simple thing but bit complicated cause of different types of authentication systems in ASP.NET Core. I update cause some people are getting null.

For JWT Authentication (Tested on ASP.NET Core v3.0.0-preview7):

var email = HttpContext.User.Claims.FirstOrDefault(c => c.Type == "sub")?.Value;

var user = await _userManager.FindByEmailAsync(email);

How to permanently remove few commits from remote branch

You git reset --hard your local branch to remove changes from working tree and index, and you git push --force your revised local branch to the remote. (other solution here, involving deleting the remote branch, and re-pushing it)

This SO answer illustrates the danger of such a command, especially if people depends on the remote history for their own local repos.
You need to be prepared to point out people to the RECOVERING FROM UPSTREAM REBASE section of the git rebase man page

With Git 2.23 (August 2019, nine years later), you would use the new command git switch.
That is: git switch -C mybranch origin/mybranch~n
(replace n by the number of commits to remove)

That will restore the index and working tree, like a git reset --hard would.
The documentation adds:

-C <new-branch>
--force-create <new-branch>

Similar to --create except that if <new-branch> already exists, it will be reset to <start-point>.
This is a convenient shortcut for:

$ git branch -f <new-branch>
$ git switch <new-branch>

Process all arguments except the first one (in a bash script)

Use this:

echo "${@:2}"

The following syntax:

echo "${*:2}"

would work as well, but is not recommended, because as @Gordon already explained, that using *, it runs all of the arguments together as a single argument with spaces, while @ preserves the breaks between them (even if some of the arguments themselves contain spaces). It doesn't make the difference with echo, but it matters for many other commands.

Setting up Gradle for api 26 (Android)

Appart from setting maven source url to your gradle, I would suggest to add both design and appcompat libraries. Currently the latest version is 26.1.0

maven {
    url ""


compile ''
compile ''

Using gdb to single-step assembly code outside specified executable causes error "cannot find bounds of current function"

Instead of gdb, run gdbtui. Or run gdb with the -tui switch. Or press C-x C-a after entering gdb. Now you're in GDB's TUI mode.

Enter layout asm to make the upper window display assembly -- this will automatically follow your instruction pointer, although you can also change frames or scroll around while debugging. Press C-x s to enter SingleKey mode, where run continue up down finish etc. are abbreviated to a single key, allowing you to walk through your program very quickly.

B+>|0x402670 <main>         push   %r15                                        |
   |0x402672 <main+2>       mov    %edi,%r15d                                  |
   |0x402675 <main+5>       push   %r14                                        |
   |0x402677 <main+7>       push   %r13                                        |
   |0x402679 <main+9>       mov    %rsi,%r13                                   |
   |0x40267c <main+12>      push   %r12                                        |
   |0x40267e <main+14>      push   %rbp                                        |
   |0x40267f <main+15>      push   %rbx                                        |
   |0x402680 <main+16>      sub    $0x438,%rsp                                 |
   |0x402687 <main+23>      mov    (%rsi),%rdi                                 |
   |0x40268a <main+26>      movq   $0x402a10,0x400(%rsp)                       |
   |0x402696 <main+38>      movq   $0x0,0x408(%rsp)                            |
   |0x4026a2 <main+50>      movq   $0x402510,0x410(%rsp)                       |
child process 21518 In: main                            Line: ??   PC: 0x402670
(gdb) file /opt/j64-602/bin/jconsole
Reading symbols from /opt/j64-602/bin/jconsole...done.
(no debugging symbols found)...done.
(gdb) layout asm
(gdb) start

How to install a specific JDK on Mac OS X?

For people using any LION OS X 10.7.X

They uploaded Java SE 6 version 1.6.0_26 available here

How to playback MKV video in web browser?

HTML5 and the VLC web plugin were a no go for me but I was able to get this work using the following setup:

DivX Web Player (NPAPI browsers only)

AC3 Audio Decoder

And here is the HTML:

<embed id="divxplayer" type="video/divx" width="1024" height="768" 
src ="path_to_file" autoPlay=\"true\" 

The DivX player seems to allow for a much wider array of video and audio options than the native HTML5, so far I am very impressed by it.

sys.argv[1] meaning in script

I would like to note that previous answers made many assumptions about the user's knowledge. This answer attempts to answer the question at a more tutorial level.

For every invocation of Python, sys.argv is automatically a list of strings representing the arguments (as separated by spaces) on the command-line. The name comes from the C programming convention in which argv and argc represent the command line arguments.

You'll want to learn more about lists and strings as you're familiarizing yourself with Python, but in the meantime, here are a few things to know.

You can simply create a script that prints the arguments as they're represented. It also prints the number of arguments, using the len function on the list.

from __future__ import print_function
import sys
print(sys.argv, len(sys.argv))

The script requires Python 2.6 or later. If you call this script, you can invoke it with different arguments to see what happens.

> python
[''] 1

> python foo and bar
['', 'foo', 'and', 'bar'] 4

> python "foo and bar"
['', 'foo and bar'] 2

> python "foo and bar" and baz
['', 'foo and bar', 'and', 'baz'] 4

As you can see, the command-line arguments include the script name but not the interpreter name. In this sense, Python treats the script as the executable. If you need to know the name of the executable (python in this case), you can use sys.executable.

You can see from the examples that it is possible to receive arguments that do contain spaces if the user invoked the script with arguments encapsulated in quotes, so what you get is the list of arguments as supplied by the user.

Now in your Python code, you can use this list of strings as input to your program. Since lists are indexed by zero-based integers, you can get the individual items using the list[0] syntax. For example, to get the script name:

script_name = sys.argv[0] # this will always work.

Although interesting, you rarely need to know your script name. To get the first argument after the script for a filename, you could do the following:

filename = sys.argv[1]

This is a very common usage, but note that it will fail with an IndexError if no argument was supplied.

Also, Python lets you reference a slice of a list, so to get another list of just the user-supplied arguments (but without the script name), you can do

user_args = sys.argv[1:] # get everything after the script name

Additionally, Python allows you to assign a sequence of items (including lists) to variable names. So if you expect the user to always supply two arguments, you can assign those arguments (as strings) to two variables:

user_args = sys.argv[1:]
fun, games = user_args # len(user_args) had better be 2

So, to answer your specific question, sys.argv[1] represents the first command-line argument (as a string) supplied to the script in question. It will not prompt for input, but it will fail with an IndexError if no arguments are supplied on the command-line following the script name.

Disable vertical sync for glxgears

If you're using the NVIDIA closed-source drivers you can vary the vertical sync mode on the fly using the __GL_SYNC_TO_VBLANK environment variable:

~$ __GL_SYNC_TO_VBLANK=1 glxgears
Running synchronized to the vertical refresh.  The framerate should be
approximately the same as the monitor refresh rate.
299 frames in 5.0 seconds = 59.631 FPS

~$ __GL_SYNC_TO_VBLANK=0 glxgears
123259 frames in 5.0 seconds = 24651.678 FPS

This works for me on Ubuntu 14.04 using the 346.46 NVIDIA drivers.

Adding image to JFrame

If you are using Netbeans to develop, use jLabel and change it's icon property.

Using Excel VBA to export data to MS Access table


Below is code that specifies fields from a named range for insertion into MS Access. The nice thing about this code is that you can name your fields in Excel whatever the hell you want (If you use * then the fields have to match exactly between Excel and Access) as you can see I have named an Excel column "Haha" even though the Access column is called "dte".

Sub test()
    dbWb = Application.ActiveWorkbook.FullName
    dsh = "[" & Application.ActiveSheet.Name & "$]" & "Data2"  'Data2 is a named range

sdbpath = "C:\Users\myname\Desktop\Database2.mdb"
sCommand = "INSERT INTO [main] ([dte], [test1], [values], [values2]) SELECT [haha],[test1],[values],[values2] FROM [Excel 8.0;HDR=YES;DATABASE=" & dbWb & "]." & dsh

Dim dbCon As New ADODB.Connection
Dim dbCommand As New ADODB.Command

dbCon.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & sdbpath & "; Jet OLEDB:Database Password=;"
dbCommand.ActiveConnection = dbCon

dbCommand.CommandText = sCommand


End Sub

Initializing an Array of Structs in C#

Are you using C# 3.0? You can use object initializers like so:

static MyStruct[] myArray = 
            new MyStruct[]{
                new MyStruct() { id = 1, label = "1" },
                new MyStruct() { id = 2, label = "2" },
                new MyStruct() { id = 3, label = "3" }

Merge two HTML table cells

Add an attribute colspan (abbriviation for 'column span') in your top cell (<td>) and set its value to 2. Your table should resembles the following;

        <td colspan = "2">
            <!-- Merged Columns -->

            <!-- Column 1 -->

            <!-- Column 2 -->

See also
     W3 official docs on HTML Tables

Link to "pin it" on pinterest without generating a button

If you want to create a simple hyperlink instead of the pin it button,

Change this:

To this:

So, a complete URL might simply look like this:

<a href="//">Pin it</a>

html table cell width for different rows

One solution would be to divide your table into 20 columns of 5% width each, then use colspan on each real column to get the desired width, like this:

<body bgcolor="#14B3D9">_x000D_
<table width="100%" border="1" bgcolor="#ffffff">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <col width="5%"><col width="5%">_x000D_
        <td colspan=5>25</td>_x000D_
        <td colspan=10>50</td>_x000D_
        <td colspan=5>25</td>_x000D_
        <td colspan=10>50</td>_x000D_
        <td colspan=6>30</td>_x000D_
        <td colspan=4>20</td>_x000D_


How to change the Text color of Menu item in Android?

For changing the text color, you can just set a custom view for the MenuItem, and then you can define the color for the text.

Sample Code : MenuItem.setActionView()

How do I make a transparent border with CSS?

This blog entry has a way to emulate border-color: transparent in IE6. The below example includes the "hasLayout" fix that is brought up in the blog entry comments:

/* transparent border */
.testDiv {
    width: 200px;
    height: 200px;
    border: solid 10px transparent;
/* IE6 fix */
*html .testDiv {
    zoom: 1;
    border-color: #FEFEFE;
    filter: chroma(color=#FEFEFE);

Make sure that the border-color used in the IE6 fix is not used anywhere in the .testDiv element. I changed the example from pink to #FEFEFE because that seems even less likely to be used.

Pretty git branch graphs

I have this git log alias in ~/.gitconfig to view the graph history:

l = log --all --graph --pretty=format:'%C(auto)%h%C(auto)%d %s %C(dim white)(%aN, %ar)'

With this in place, git l will output something like:

enter image description here

In Git 2.12+ you can even customize the line colors of the graph using the log.graphColors configuration option.

As for the logs' format, it's similar to --oneline, with the addition of the author name (respecting .mailmap) and the relative author date. Note that the %C(auto) syntax, which tells Git to use the default colors for commit hash, etc. is supported in Git >= 1.8.3.

Spring CORS No 'Access-Control-Allow-Origin' header is present

Following on Omar's answer, I created a new class file in my REST API project called with this configuration:

public class WebConfig extends WebMvcConfigurerAdapter {

  public void addCorsMappings(CorsRegistry registry) {

This allows any origin to access the API and applies it to all controllers in the Spring project.

How to convert a private key to an RSA private key?

This may be of some help (do not literally write out the backslashes '\' in the commands, they are meant to indicate that "everything has to be on one line"):

Which Command to Apply When

It seems that all the commands (in grey) take any type of key file (in green) as "in" argument. Which is nice.

Here are the commands again for easier copy-pasting:

openssl rsa                                                -in $FF -out $TF
openssl rsa -aes256                                        -in $FF -out $TF
openssl pkcs8 -topk8 -nocrypt                              -in $FF -out $TF
openssl pkcs8 -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA256 -in $FF -out $TF


openssl rsa -check -in $FF
openssl rsa -text  -in $FF

Remove all child elements of a DOM node in JavaScript

Just saw someone mention this question in another and thought I would add a method I didn't see yet:

function clear(el) {
    el.parentNode.replaceChild(el.cloneNode(false), el);

var myNode = document.getElementById("foo");

The clear function is taking the element and using the parent node to replace itself with a copy without it's children. Not much performance gain if the element is sparse but when the element has a bunch of nodes the performance gains are realized.

Releasing memory in Python

I'm guessing the question you really care about here is:

Is there a way to force Python to release all the memory that was used (if you know you won't be using that much memory again)?

No, there is not. But there is an easy workaround: child processes.

If you need 500MB of temporary storage for 5 minutes, but after that you need to run for another 2 hours and won't touch that much memory ever again, spawn a child process to do the memory-intensive work. When the child process goes away, the memory gets released.

This isn't completely trivial and free, but it's pretty easy and cheap, which is usually good enough for the trade to be worthwhile.

First, the easiest way to create a child process is with concurrent.futures (or, for 3.1 and earlier, the futures backport on PyPI):

with concurrent.futures.ProcessPoolExecutor(max_workers=1) as executor:
    result = executor.submit(func, *args, **kwargs).result()

If you need a little more control, use the multiprocessing module.

The costs are:

  • Process startup is kind of slow on some platforms, notably Windows. We're talking milliseconds here, not minutes, and if you're spinning up one child to do 300 seconds' worth of work, you won't even notice it. But it's not free.
  • If the large amount of temporary memory you use really is large, doing this can cause your main program to get swapped out. Of course you're saving time in the long run, because that if that memory hung around forever it would have to lead to swapping at some point. But this can turn gradual slowness into very noticeable all-at-once (and early) delays in some use cases.
  • Sending large amounts of data between processes can be slow. Again, if you're talking about sending over 2K of arguments and getting back 64K of results, you won't even notice it, but if you're sending and receiving large amounts of data, you'll want to use some other mechanism (a file, mmapped or otherwise; the shared-memory APIs in multiprocessing; etc.).
  • Sending large amounts of data between processes means the data have to be pickleable (or, if you stick them in a file or shared memory, struct-able or ideally ctypes-able).

deleting rows in numpy array

This is similar to your original approach, and will use less space than unutbu's answer, but I suspect it will be slower.

>>> import numpy as np
>>> p = np.array([[1.5, 0], [1.4,1.5], [1.6, 0], [1.7, 1.8]])
>>> p
array([[ 1.5,  0. ],
       [ 1.4,  1.5],
       [ 1.6,  0. ],
       [ 1.7,  1.8]])
>>> nz = (p == 0).sum(1)
>>> q = p[nz == 0, :]
>>> q
array([[ 1.4,  1.5],
       [ 1.7,  1.8]])

By the way, your line p.delete() doesn't work for me - ndarrays don't have a .delete attribute.

How to display HTML in TextView?

Simply use:

String variable="StackOverflow";
textView.setText(Html.fromHtml("<b>Hello : </b>"+ variable));

What is the iBeacon Bluetooth Profile

iBeacon Profile contains 31 Bytes which includes the followings

  1. Prefix - 9 Bytes - which include s the adv data and Manufacturer data
  2. UUID - 16 Bytes
  3. Major - 2 Bytes
  4. Minor - 2 Bytes
  5. TxPower - 1 Byte

enter image description here

python multithreading wait till all threads finished

I just came across the same problem where I needed to wait for all the threads which were created using the for loop.I just tried out the following piece of code.It may not be the perfect solution but I thought it would be a simple solution to test:

for t in threading.enumerate():
    except RuntimeError as err:
        if 'cannot join current thread' in err:

How to make a JFrame Modal in Swing java

not sure the contetns of your JFrame, if you ask some input from users, you can use JOptionPane, this also can set JFrame as modal

            JFrame frame = new JFrame();
            String bigList[] = new String[30];

            for (int i = 0; i < bigList.length; i++) {
              bigList[i] = Integer.toString(i);

                    "Select a item", 
                    "The List", 

How to get Rails.logger printing to the console/stdout when running rspec?

For Rails 4, see this answer.

For Rails 3.x, configure a logger in config/environments/test.rb:

config.logger =
config.logger.level = Logger::ERROR

This will interleave any errors that are logged during testing to STDOUT. You may wish to route the output to STDERR or use a different log level instead.

Sending these messages to both the console and a log file requires something more robust than Ruby's built-in Logger class. The logging gem will do what you want. Add it to your Gemfile, then set up two appenders in config/environments/test.rb:

logger = Logging.logger['test']
logger.level = :info
config.logger = logger

How to access html form input from code behind

Since you're using code-behind, add an id to the element and runat=server.

You can then reference the objects in the code behind.

Connect to SQL Server database from Node.js

This is mainly for future readers. As the question (at least the title) focuses on "connecting to sql server database from node js", I would like to chip in about "mssql" node module.

At this moment, we have a stable version of Microsoft SQL Server driver for NodeJs ("msnodesql") available here: While it does a great job of native integration to Microsoft SQL Server database (than any other node module), there are couple of things to note about.

"msnodesql" require a few pre-requisites (like python, VC++, SQL native client etc.) to be installed on the host machine. That makes your "node" app "Windows" dependent. If you are fine with "Windows" based deployment, working with "msnodesql" is the best.

On the other hand, there is another module called "mssql" (available here which can work with "tedious" or "msnodesql" based on configuration. While this module may not be as comprehensive as "msnodesql", it pretty much solves most of the needs.

If you would like to start with "mssql", I came across a simple and straight forward video, which explains about connecting to Microsoft SQL Server database using NodeJs here:

Source code for the above video is available here:

Just in case, if the above links are not working, I am including the source code here:

var sql = require("mssql");_x000D_
var dbConfig = {_x000D_
    server: "localhost\\SQL2K14",_x000D_
    database: "SampleDb",_x000D_
    user: "sa",_x000D_
    password: "sql2014",_x000D_
    port: 1433_x000D_
function getEmp() {_x000D_
    var conn = new sql.Connection(dbConfig);_x000D_
    conn.connect().then(function () {_x000D_
        var req = new sql.Request(conn);_x000D_
        req.query("SELECT * FROM emp").then(function (recordset) {_x000D_
        .catch(function (err) {_x000D_
        });        _x000D_
    .catch(function (err) {_x000D_
    //--> another way_x000D_
    //var req = new sql.Request(conn);_x000D_
    //conn.connect(function (err) {_x000D_
    //    if (err) {_x000D_
    //        console.log(err);_x000D_
    //        return;_x000D_
    //    }_x000D_
    //    req.query("SELECT * FROM emp", function (err, recordset) {_x000D_
    //        if (err) {_x000D_
    //            console.log(err);_x000D_
    //        }_x000D_
    //        else { _x000D_
    //            console.log(recordset);_x000D_
    //        }_x000D_
    //        conn.close();_x000D_
    //    });_x000D_

The above code is pretty self explanatory. We define the db connection parameters (in "dbConfig" JS object) and then use "Connection" object to connect to SQL Server. In order to execute a "SELECT" statement, in this case, it uses "Request" object which internally works with "Connection" object. The code explains both flavors of using "promise" and "callback" based executions.

The above source code explains only about connecting to sql server database and executing a SELECT query. You can easily take it to the next level by following documentation of "mssql" node available at:

UPDATE: There is a new video which does CRUD operations using pure Node.js REST standard (with Microsoft SQL Server) here: It is a fantastic video which explains everything from scratch (it has got heck a lot of code and it will not be that pleasing to explain/copy the entire code here)

Keyboard shortcuts are not active in Visual Studio with Resharper installed

Try this steps:

1) Resharper > Options > Keyboard & Menus

Then point choose:

  • Hide overridden Visual Studio menu items (Check)
  • Visual Studio (Check)

Then click on Apply Scheme and Save.

2) Tools > Options > Environment > Keyboard

  • Click Reset
  • Click Ok

Cannot read property 'addEventListener' of null

I simply added 'async' to my script tag, which seems to have fixed the issue. I'm not sure why, if someone can explain, but it worked for me. My guess is that the page isn't waiting for the script to load, so the page loads at the same time as the JavaScript.

Async/Await enables us to write asynchronous code in a synchronous fashion. it’s just syntactic sugar using generators and yield statements to “pause” execution, giving us the ability to assign it to a variable!

Here's reference link-

stdlib and colored output in C

All modern terminal emulators use ANSI escape codes to show colours and other things.
Don't bother with libraries, the code is really simple.

More info is here.

Example in C:

#include <stdio.h>

#define ANSI_COLOR_RED     "\x1b[31m"
#define ANSI_COLOR_GREEN   "\x1b[32m"
#define ANSI_COLOR_YELLOW  "\x1b[33m"
#define ANSI_COLOR_BLUE    "\x1b[34m"
#define ANSI_COLOR_MAGENTA "\x1b[35m"
#define ANSI_COLOR_CYAN    "\x1b[36m"
#define ANSI_COLOR_RESET   "\x1b[0m"

int main (int argc, char const *argv[]) {

  printf(ANSI_COLOR_RED     "This text is RED!"     ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_GREEN   "This text is GREEN!"   ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_YELLOW  "This text is YELLOW!"  ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_BLUE    "This text is BLUE!"    ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_CYAN    "This text is CYAN!"    ANSI_COLOR_RESET "\n");

  return 0;

Invariant Violation: _registerComponent(...): Target container is not a DOM element

it's easy just make basic HTML CSS js and render the script from js

mport React from 'react';_x000D_
import ReactDOM from 'react-dom';_x000D_
import './index.css';_x000D_
var destination = document.querySelector('#container');_x000D_
<p> hello world</p>_x000D_
</div>, destination_x000D_
    text-align: center;_x000D_
    background-color: aqua;_x000D_
  padding: 50px;_x000D_
  border-color: aqua;_x000D_
  font-family: sans-serif;_x000D_
  display: flex;_x000D_
  justify-content: flex;_x000D_
<!DOCTYPE html>_x000D_
<html lang="en">_x000D_
    <meta charset="utf-8" />_x000D_
    <meta name="viewport" content="width=device-width, initial-scale=1" />_x000D_
    <meta name="theme-color" content="#000000" />_x000D_
      content="Web site created using create-react-app"_x000D_
    />   _x000D_
    <title> app  </title>_x000D_
    <div id="container">_x000D_

Multiple INSERT statements vs. single INSERT with multiple VALUES

The issue probably has to do with the time it takes to compile the query.

If you want to speed up the inserts, what you really need to do is wrap them in a transaction:

INSERT INTO T_TESTS (TestId, FirstName, LastName, Age) 
   VALUES ('6f3f7257-a3d8-4a78-b2e1-c9b767cfe1c1', 'First 0', 'Last 0', 0);
INSERT INTO T_TESTS (TestId, FirstName, LastName, Age) 
   VALUES ('32023304-2e55-4768-8e52-1ba589b82c8b', 'First 1', 'Last 1', 1);
INSERT INTO T_TESTS (TestId, FirstName, LastName, Age) 
   VALUES ('f34d95a7-90b1-4558-be10-6ceacd53e4c4', 'First 999', 'Last 999', 999);

From C#, you might also consider using a table valued parameter. Issuing multiple commands in a single batch, by separating them with semicolons, is another approach that will also help.

Java Does Not Equal (!=) Not Working?

do the one of these.

        //do something


        //do something

CSS white space at bottom of page despite having both min-height and height tag

There is a second paragraph in your footer that contains a script. It is this that is causing the issue.

.map() a Javascript ES6 Map?

You can use this function:

function mapMap(map, fn) {
  return new Map(Array.from(map, ([key, value]) => [key, fn(value, key, map)]));


var map1 = new Map([["A", 2], ["B", 3], ["C", 4]]);

var map2 = mapMap(map1, v => v * v);

console.log(map1, map2);
Map { A ? 2, B ? 3, C ? 4 }
Map { A ? 4, B ? 9, C ? 16 }

Javascript/jQuery: Set Values (Selection) in a multiple Select

Basically do a values.split(',') and then loop through the resulting array and set the Select.

Bash integer comparison

I know this has been answered, but here's mine just because I think case is an under-appreciated tool. (Maybe because people think it is slow, but it's at least as fast as an if, sometimes faster.)

case "$1" in
    0|1) xinput set-prop 12 "Device Enabled" $1 ;;
      *) echo "This script requires a 1 or 0 as first parameter." ;;

How do I make a Mac Terminal pop-up/alert? Applescript?

This would restore focus to the previous application and exit the script if the answer was empty.

a=$(osascript -e 'try
tell app "SystemUIServer"
set answer to text returned of (display dialog "" default answer "")
activate app (path to frontmost application as text)
answer' | tr '\r' ' ')
[[ -z "$a" ]] && exit

If you told System Events to display the dialog, there would be a small delay if it wasn't running before.

For documentation about display dialog, open the dictionary of Standard Additions in AppleScript Editor or see the AppleScript Language Guide.

set option "selected" attribute from dynamic created option

select = document.getElementById('selectId');
var opt = document.createElement('option');
    opt.value = 'value';
    opt.innerHTML = 'name';
    opt.selected = true;

How to show soft-keyboard when edittext is focused

It worked for me. You can try with this also to show the keyboard:


PowerShell on Windows 7: Set-ExecutionPolicy for regular users

If you (or a helpful admin) runs Set-ExecutionPolicy as administrator, the policy will be set for all users. (I would suggest "remoteSigned" rather than "unrestricted" as a safety measure.)

NB.: On a 64-bit OS you need to run Set-ExecutionPolicy for 32-bit and 64-bit PowerShell separately.

Search an array for matching attribute

you can also use the Array.find feature of es6. the doc is here

return restaurants.find(item => {
   return == 'chicken'

Is an entity body allowed for an HTTP DELETE request?

It is worth noting that the OpenAPI specification for version 3.0 dropped support for DELETE methods with a body:

see here and here for references

This may affect your implementation, documentation, or use of these APIs in the future.

Batch File; List files in directory, only filenames?

The full command is:

dir /b /a-d

Let me break it up;

Basically the /b is what you look for.

/a-d will exclude the directory names.

For more information see dir /? for other arguments that you can use with the dir command.

Pandas convert string to int

You need add parameter errors='coerce' to function to_numeric:

ID = pd.to_numeric(ID, errors='coerce')

If ID is column:

df.ID = pd.to_numeric(df.ID, errors='coerce')

but non numeric are converted to NaN, so all values are float.

For int need convert NaN to some value e.g. 0 and then cast to int:

df.ID = pd.to_numeric(df.ID, errors='coerce').fillna(0).astype(np.int64)


df = pd.DataFrame({'ID':['4806105017087','4806105017087','CN414149']})
print (df)
0  4806105017087
1  4806105017087
2       CN414149

print (pd.to_numeric(df.ID, errors='coerce'))
0    4.806105e+12
1    4.806105e+12
2             NaN
Name: ID, dtype: float64

df.ID = pd.to_numeric(df.ID, errors='coerce').fillna(0).astype(np.int64)
print (df)
0  4806105017087
1  4806105017087
2              0

EDIT: If use pandas 0.25+ then is possible use integer_na:

df.ID = pd.to_numeric(df.ID, errors='coerce').astype('Int64')
print (df)
0  4806105017087
1  4806105017087
2            NaN

Get age from Birthdate

function getAge(birthday) {
    var today = new Date();
    var thisYear = 0;
    if (today.getMonth() < birthday.getMonth()) {
        thisYear = 1;
    } else if ((today.getMonth() == birthday.getMonth()) && today.getDate() < birthday.getDate()) {
        thisYear = 1;
    var age = today.getFullYear() - birthday.getFullYear() - thisYear;
    return age;


tqdm in Jupyter Notebook prints new progress bars repeatedly

None of the above works for me. I find that running the following sorts this issue after error (It just clears all the instances of progress bars in the background):

from tqdm import tqdm

# blah blah your code errored


How do I use DrawerLayout to display over the ActionBar/Toolbar and under the status bar?

All answers mentioned here are too old and lengthy.The best and short solution that work with latest Navigationview is

public void onDrawerSlide(View drawerView, float slideOffset) {
    super.onDrawerSlide(drawerView, slideOffset);

    try {
        //int currentapiVersion = android.os.Build.VERSION.SDK_INT;
        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP){
            // Do something for lollipop and above versions

        Window window = getWindow();

        // clear FLAG_TRANSLUCENT_STATUS flag:

        // add FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS flag to the window

        // finally change the color to any color with transparency


    } catch (Exception e) {



this is going to change your status bar color to transparent when you open the drawer

Now when you close the drawer you need to change status bar color again to dark.So you can do it in this way.

        public void onDrawerClosed(View drawerView) {
        try {
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP){
    // Do something for lollipop and above versions

    Window window = getWindow();

    // clear FLAG_TRANSLUCENT_STATUS flag:

    // add FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS flag to the window

    // finally change the color again to dark
    } catch (Exception e) {

and then in main layout add a single line i.e


and your drawer layout will look like


and your navigation view will look like


I have tested it and its fully working.Hope it helps someone.This may not be the best approach but it works smoothly and is simple to implement. Mark it up if it helps.Happy coding :)

app.config for a class library

Jon, a lot of opinion has been given that didn't correctly answer your question.

I will give MY OPINION and then tell you how to do exactly what you asked for.

I see no reason why an assembly couldn't have its own config file. Why is the first level of atomicy (is that a real word?) be at the application level? Why not at the solution level? It's an arbitrary, best-guess decision and as such, an OPINION. If you were to write a logging library and wanted to include a configuration file for it, that would be used globally, why couldn't you hook into the built-in settings functionality? We've all done it ... tried to provide "powerful" functionality to other developers. How? By making assumptions that inherently translated to restrictions. That's exactly what MS did with the settings framework, so you do have to "fool it" a little.

To directly answer your question, simply add the configuration file manually (xml) and name it to match your library and to include the "config" extension. Example:


Next, use the ConfigurationManager to load the file and access settings:

string assemblyPath = new Uri(Assembly.GetExecutingAssembly().CodeBase).AbsolutePath;
Configuration cfg = ConfigurationManager.OpenExeConfiguration(assemblyPath);
string result = cfg.AppSettings.Settings["TEST_SETTING"].Value;

Note that this fully supports the machine.config heierarchy, even though you've explicitly chosen the app config file. In other words, if the setting isn't there, it will resolve higher. Settings will also override machine.config entries.

What does appending "?v=1" to CSS and JavaScript URLs in link and script tags do?

As you can read before, the ?v=1 ensures that your browser gets the version 1 of the file. When you have a new version, you just have to append a different version number and the browser will forget about the old version and loads the new one.

There is a gulp plugin which takes care of version your files during the build phase, so you don't have to do it manually. It's handy and you can easily integrate it in you build process. Here's the link: gulp-annotate

What does -z mean in Bash?


string is null, that is, has zero length

String=''   # Zero-length ("null") string variable.

if [ -z "$String" ]
  echo "\$String is null."
  echo "\$String is NOT null."
fi     # $String is null.

Safely turning a JSON string into an object

Older question, I know, however nobody notice this solution by using new Function(), an anonymous function that returns the data.

Just an example:

 var oData = 'test1:"This is my object",test2:"This is my object"';

 if( typeof oData !== 'object' )
  try {
   oData = (new Function('return {'+oData+'};'))();
  catch(e) { oData=false; }

 if( typeof oData !== 'object' )
  { alert( 'Error in code' ); }
 else {
        alert( oData.test1 );
        alert( oData.test2 );

This is a little more safe because it executes inside a function and do not compile in your code directly. So if there is a function declaration inside it, it will not be bound to the default window object.

I use this to 'compile' configuration settings of DOM elements (for example the data attribute) simple and fast.

How can I check if a value is of type Integer?

Try maybe this way

    double d= Double.valueOf(someString);
    if (d==(int)d){
}catch(Exception e){
    System.out.println("not number");

But all numbers outside Integers range (like "-1231231231231231238") will be treated as doubles. If you want to get rid of that problem you can try it this way

try {
    double d = Double.valueOf(someString);
    if (someString.matches("\\-?\\d+")){//optional minus and at least one digit
        System.out.println("integer" + d);
    } else {
        System.out.println("double" + d);
} catch (Exception e) {
    System.out.println("not number");

Setting the height of a DIV dynamically

document.getElementById('myDiv').style.height = 500;

This is the very basic JS code required to adjust the height of your object dynamically. I just did this very thing where I had some auto height property, but when I add some content via XMLHttpRequest I needed to resize my parent div and this offsetheight property did the trick in IE6/7 and FF3

How can I change the default Mysql connection timeout when connecting through python?

MAX_EXECUTION_TIME is also an important parameter for long running queries.Will work for MySQL 5.7 or later.

Check the current value


Then set it according to your needs.


How do I set the figure title and axes labels font size in Matplotlib?

You can also do this globally via a rcParams dictionary:

import matplotlib.pylab as pylab
params = {'legend.fontsize': 'x-large',
          'figure.figsize': (15, 5),
         'axes.labelsize': 'x-large',

Split output of command by columns using Bash?

Bash's set will parse all output into position parameters.

For instance, with set $(free -h) command, echo $7 will show "Mem:"

How to export JSON from MongoDB using Robomongo

If you want to use mongoimport, you'll want to export this way:

  .find({_id: 'q3hrnnoKu2mnCL7kE'})

How to get the dimensions of a tensor (in TensorFlow) at graph construction time?

I see most people confused about tf.shape(tensor) and tensor.get_shape() Let's make it clear:

  1. tf.shape

tf.shape is used for dynamic shape. If your tensor's shape is changable, use it. An example: a input is an image with changable width and height, we want resize it to half of its size, then we can write something like:
new_height = tf.shape(image)[0] / 2

  1. tensor.get_shape

tensor.get_shape is used for fixed shapes, which means the tensor's shape can be deduced in the graph.

Conclusion: tf.shape can be used almost anywhere, but t.get_shape only for shapes can be deduced from graph.

Save child objects automatically using JPA Hibernate

I tried the above but I'm getting a database error complaining that the foreign key field in the Child table can not be NULL. Is there a way to tell JPA to automatically set this foreign key into the Child object so it can automatically save children objects?

Well, there are two things here.

First, you need to cascade the save operation (but my understanding is that you are doing this or you wouldn't get a FK constraint violation during inserts in the "child" table)

Second, you probably have a bidirectional association and I think that you're not setting "both sides of the link" correctly. You are supposed to do something like this:

Parent parent = new Parent();
Child c1 = new Child();

List<Child> children = new ArrayList<Child>();

A common pattern is to use link management methods:

public class Parent {
    @Id private Long id;

    private List<Child> children = new ArrayList<Child>();


    protected void setChildren(List<Child> children) {
        this.children = children;

    public void addToChildren(Child child) {

And the code becomes:

Parent parent = new Parent();
Child c1 = new Child();


How to resolve git status "Unmerged paths:"?

All you should need to do is:

# if the file in the right place isn't already committed:
git add <path to desired file>

# remove the "both deleted" file from the index:
git rm --cached ../public/images/originals/

# commit the merge:
git commit

Create dataframe from a matrix

I've found the following "cheat" to work very neatly and error-free

> dimnames <- list(time=c(0, 0.5, 1), name=c("C_0", "C_1"))
> mat <- matrix(data, ncol=2, nrow=3, dimnames=dimnames)
> head(mat, 2) #this returns the number of rows indicated in a data frame format
> df <- data.frame(head(mat, 2)) #"data.frame" might not be necessary

Et voila!

How to change default timezone for Active Record in Rails?

In Ruby on Rails 6.0.1 go to config > locales > application.rb y agrega lo siguiente:

require_relative 'boot'

require 'rails/all'

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.

module CrudRubyOnRails6
  class Application < Rails::Application
    # Initialize configuration defaults for originally generated Rails version.
    config.load_defaults 6.0

    config.active_record.default_timezone = :local
    config.time_zone = 'Lima'

    # Settings in config/environments/* take precedence over those specified here.
    # Application configuration can go into files in config/initializers
    # -- all .rb files in that directory are automatically loaded after loading
    # the framework and any gems in your application.

You can see that I am configuring the time zone with 2 lines:

config.active_record.default_timezone =: local
config.time_zone = 'Lima'

I hope it helps those who are working with Ruby on Rails 6.0.1

Height of an HTML select box (dropdown)

You can change the height of one. Don't use height="500"(Just an example number). Use the style. You can use <style>tag or just use this:

<!DOCTYPE html>
  <select id="option" style="height: 100px;">
    <option value="1">Option 1
    <option value="2">Option 2

I spotlight the change:

  <select id="option" style="height: 100px;">

And even better...

style="height: 100px;">

You see that?

Please up vote if it's helpful!

Minimum and maximum date

To augment T.J.'s answer, exceeding the min/max values generates an Invalid Date.

let maxDate = new Date(8640000000000000);_x000D_
let minDate = new Date(-8640000000000000);_x000D_
console.log(new Date(maxDate.getTime()).toString());_x000D_
console.log(new Date(maxDate.getTime() - 1).toString());_x000D_
console.log(new Date(maxDate.getTime() + 1).toString()); // Invalid Date_x000D_
console.log(new Date(minDate.getTime()).toString());_x000D_
console.log(new Date(minDate.getTime() + 1).toString());_x000D_
console.log(new Date(minDate.getTime() - 1).toString()); // Invalid Date

Generating a WSDL from an XSD file

Personally (and given what I know, i.e., Java and axis), I'd generate a Java data model from the .xsd files (Axis 2 can do this), and then add an interface to describe my web service that uses that model, and then generate a WSDL from that interface.

Because .NET has all these features as well, it must be possible to do all this in that ecosystem as well.

PHP to search within txt file and echo the whole line

looks like you're better off systeming out to system("grep \"$QUERY\"") since that script won't be particularly high performance either way. Otherwise shows you how to loop over lines and you can use for finding matches.

python numpy/scipy curve fitting

You'll first need to separate your numpy array into two separate arrays containing x and y values.

x = [1, 2, 3, 9]
y = [1, 4, 1, 3]

curve_fit also requires a function that provides the type of fit you would like. For instance, a linear fit would use a function like

def func(x, a, b):
    return a*x + b

scipy.optimize.curve_fit(func, x, y) will return a numpy array containing two arrays: the first will contain values for a and b that best fit your data, and the second will be the covariance of the optimal fit parameters.

Here's an example for a linear fit with the data you provided.

import numpy as np
from scipy.optimize import curve_fit

x = np.array([1, 2, 3, 9])
y = np.array([1, 4, 1, 3])

def fit_func(x, a, b):
    return a*x + b

params = curve_fit(fit_func, x, y)

[a, b] = params[0]

This code will return a = 0.135483870968 and b = 1.74193548387

Here's a plot with your points and the linear fit... which is clearly a bad one, but you can change the fitting function to obtain whatever type of fit you would like.

enter image description here

How to check if click event is already bound - JQuery

I wrote a very tiny plugin called "once" which do that. Execute off and on in element.

$.fn.once = function(a, b) {
    return this.each(function() {

And simply:

$(element).once('click', function(){

Eclipse CDT: no rule to make target all

In C/C++ Build -> Builder Settings, select Internal builder (instead of External builder).

It works for me.

Windows- Pyinstaller Error "failed to execute script " When App Clicked

That error is due to missing of modules in pyinstaller. You can find the missing modules by running script in executable command line, i.e., by removing '-w' from the command. Once you created the command line executable file then in command line it will show the missing modules. By finding those missing modules you can add this to your command : " --hidden-import = missingmodule "

I solved my problem through this.

IIS: Where can I find the IIS logs?


Check the identity of the site going to sites and advanced settings

How to write log base(2) in c/c++

Improved version of what Ustaman Sangat did

static inline uint64_t
log2(uint64_t n)
    uint64_t val;
    for (val = 0; n > 1; val++, n >>= 1);

    return val;

Closing Twitter Bootstrap Modal From Angular Controller

You can do it like this:


Why and when to use angular.copy? (Deep Copy)

When using angular.copy, instead of updating the reference, a new object is created and assigned to the destination(if a destination is provided). But there's more. There's this cool thing that happens after a deep copy.

Say you have a factory service which has methods which updates factory variables.

angular.module('test').factory('TestService', [function () {
    var o = {
        shallow: [0,1], // initial value(for demonstration)
        deep: [0,2] // initial value(for demonstration)
    o.shallowCopy = function () {
        o.shallow = [1,2,3]
    o.deepCopy = function () {
        angular.copy([4,5,6], o.deep);
    return o;

and a controller which uses this service,

angular.module('test').controller('Ctrl', ['TestService', function (TestService) {
     var shallow = TestService.shallow;
     var deep = TestService.deep;

     console.log('****Printing initial values');


     console.log('****Printing values after service method execution');

     console.log('****Printing service variables directly');

When the above program is run the output will be as follows,

****Printing initial values

****Printing values after service method execution

****Printing service variables directly

Thus the cool thing about using angular copy is that, the references of the destination are reflected with the change of values, without having to re-assign the values manually, again.

Service vs IntentService in the Android platform

Tejas Lagvankar wrote a nice post about this subject. Below are some key differences between Service and IntentService.

When to use?

  • The Service can be used in tasks with no UI, but shouldn't be too long. If you need to perform long tasks, you must use threads within Service.

  • The IntentService can be used in long tasks usually with no communication to Main Thread. If communication is required, can use Main Thread handler or broadcast intents. Another case of use is when callbacks are needed (Intent triggered tasks).

How to trigger?

  • The Service is triggered by calling method startService().

  • The IntentService is triggered using an Intent, it spawns a new worker thread and the method onHandleIntent() is called on this thread.

Triggered From

  • The Service and IntentService may be triggered from any thread, activity or other application component.

Runs On

  • The Service runs in background but it runs on the Main Thread of the application.

  • The IntentService runs on a separate worker thread.

Limitations / Drawbacks

  • The Service may block the Main Thread of the application.

  • The IntentService cannot run tasks in parallel. Hence all the consecutive intents will go into the message queue for the worker thread and will execute sequentially.

When to stop?

  • If you implement a Service, it is your responsibility to stop the service when its work is done, by calling stopSelf() or stopService(). (If you only want to provide binding, you don't need to implement this method).

  • The IntentService stops the service after all start requests have been handled, so you never have to call stopSelf().

Visual Studio Code Search and Replace with Regular Expressions

For beginners, I wanted to add to the accepted answer, because a couple of subtleties were unclear to me:

To find and modify text (not completely replace),

  1. In the "Find" step, you can use regex with "capturing groups," e.g. your search could be la la la (group1) blah blah (group2), using parentheses.

  2. And then in the "Replace" step, you can refer to the capturing groups via $1, $2 etc.

So, for example, in this case we could find the relevant text with just <h1>.+?<\/h1> (no parentheses), but putting in the parentheses <h1>(.+?)<\/h1> allows us to refer to the sub-match in between them as $1 in the replace step. Cool!


  • To turn on Regex in the Find Widget, click the .* icon, or press Cmd/Ctrl Alt R

  • $0 refers to the whole match

  • Finally, the original question states that the replace should happen "within a document," so you can use the "Find Widget" (Cmd or Ctrl + F), which is local to the open document, instead of "Search", which opens a bigger UI and looks across all files in the project.

How to zoom div content using jquery?

Used zoom-master/jquery.zoom.js. The zoom for the image worked perfectly. Here is a link to the page.



JSON to pandas DataFrame

I prefer a more generic method in which may be user doesn't prefer to give key 'results'. You can still flatten it by using a recursive approach of finding key having nested data or if you have key but your JSON is very nested. It is something like:

from pandas import json_normalize

def findnestedlist(js):
    for i in js.keys():
        if isinstance(js[i],list):
            return js[i]
    for v in js.values():
        if isinstance(v,dict):
            return check_list(v)

def recursive_lookup(k, d):
    if k in d:
        return d[k]
    for v in d.values():
        if isinstance(v, dict):
            return recursive_lookup(k, v)
    return None

def flat_json(content,key):
    nested_list = []
    js = json.loads(content)
    if key is None or key == '':
        nested_list = findnestedlist(js)
        nested_list = recursive_lookup(key, js)
    return json_normalize(nested_list,sep="_")

key = "results" # If you don't have it, give it None

csv_data = flat_json(your_json_string,root_key)

Why am I getting an Exception with the message "Invalid setup on a non-virtual (overridable in VB) member..."?

Instead of mocking concrete class you should mock that class interface. Extract interface from XmlCupboardAccess class

public interface IXmlCupboardAccess
    bool IsDataEntityInXmlCupboard(string dataId, out string nameInCupboard, out string refTypeInCupboard, string nameTemplate = null);

And instead of

private Mock<XmlCupboardAccess> _xmlCupboardAccess = new Mock<XmlCupboardAccess>();

change to

private Mock<IXmlCupboardAccess> _xmlCupboardAccess = new Mock<IXmlCupboardAccess>();

JSON encode MySQL results

$rows = json_decode($mysql_result,true);

as simple as that :-)

How to get the correct range to set the value to a cell?

The following code does what is required

function doTest() {

How to add a custom CA Root certificate to the CA Store used by pip in Windows?

Not best answer but you can reuse an already created ca bundle using --cert option of pip, for instance:

pip install SQLAlchemy==1.1.15 --cert="C:\Users\myUser\certificates\my_ca-bundle.crt"

Deleting Row in SQLite in Android

if you are using SQLiteDatabase then there is a delete method

Definition of Delete

int delete (String table, String whereClause, String[] whereArgs)

Example Implementation

Now we can write a method called delete with argument as name

public void delete(String value) {
    db.delete(DATABASE_TABLE, KEY_NAME + "=?", new String[]{String.valueOf(value)});

if you want to delete all records then just pass null to the above method,

public void delete() {
    db.delete(DATABASE_TABLE, null, null);

Source Of Information

git pull remote branch cannot find remote ref

The branch name in Git is case sensitive. To see the names of your branches that Git 'sees' (including the correct casing), use:

git branch -vv

... and now that you can see the correct branch name to use, do this:

git pull origin BranchName 

where 'BranchName' is the name of your branch. Ensure that you match the case correctly

So in the OP's (Original Poster's) case, the command would be:

git pull origin DownloadManager

SQL query for getting data for last 3 months


Mureinik's suggested method will return the same results, but doing it this way your query can benefit from any indexes on Date_Column.

or you can check against last 90 days.

WHERE Date_Column >= DATEADD(DAY, -90, GETDATE()) 

Clear git local cache

git rm --cached *.FileExtension

This must ignore all files from this extension

Spring: @Component versus @Bean

You can use @Bean to make an existing third-party class available to your Spring framework application context.

public ViewResolver viewResolver() {

    InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();


    return viewResolver;

By using the @Bean annotation, you can wrap a third-party class (it may not have @Component and it may not use Spring), as a Spring bean. And then once it is wrapped using @Bean, it is as a singleton object and available in your Spring framework application context. You can now easily share/reuse this bean in your app using dependency injection and @Autowired.

So think of the @Bean annotation is a wrapper/adapter for third-party classes. You want to make the third-party classes available to your Spring framework application context.

By using @Bean in the code above, I'm explicitly declare a single bean because inside of the method, I'm explicitly creating the object using the new keyword. I'm also manually calling setter methods of the given class. So I can change the value of the prefix field. So this manual work is referred to as explicit creation. If I use the @Component for the same class, the bean registered in the Spring container will have default value for the prefix field.

On the other hand, when we annotate a class with @Component, no need for us to manually use the new keyword. It is handled automatically by Spring.

How to erase the file contents of text file in Python?

Not a complete answer more of an extension to ondra's answer

When using truncate() ( my preferred method ) make sure your cursor is at the required position. When a new file is opened for reading - open('FILE_NAME','r') it's cursor is at 0 by default. But if you have parsed the file within your code, make sure to point at the beginning of the file again i.e truncate(0) By default truncate() truncates the contents of a file starting from the current cusror position.

A simple example

How to run .sh on Windows Command Prompt?

The error message indicates that you have not installed bash, or it is not in your PATH.

The top Google hit is but you also need to understand that most Bash scripts expect a Unix-like environment; so just installing Bash is probably unlikely to allow you to run a script you found on the net, unless it was specifically designed for this particular usage scenario. The usual solution to that is but there are many possible alternatives, depending on what exactly it is that you want to accomplish.

If Windows is not central to your usage scenario, installing a free OS (perhaps virtualized) might be the simplest way forward.

The second error message is due to the fact that Windows nominally accepts forward slash as a directory separator, but in this context, it is being interpreted as a switch separator. In other words, Windows parses your command line as app /build / (or, to paraphrase with Unix option conventions, app --build You could try app\build\ but it is unlikely to work, because of the circumstances outlined above.

How can I reduce the waiting (ttfb) time

I would suggest you read this article and focus more on how to optimize the overall response to the user request (either a page, a search result etc.)

A good argument for this is the example they give about using gzip to compress the page. Even though ttfb is faster when you do not compress, the overall experience of the user is worst because it takes longer to download content that is not zipped.

Determining if Swift dictionary contains key and obtaining any of its values

The accepted answer let keyExists = dict[key] != nil will not work if the Dictionary contains the key but has a value of nil.

If you want to be sure the Dictionary does not contain the key at all use this (tested in Swift 4).

if dict.keys.contains(key) {
  // contains key
} else { 
  // does not contain key

How to add parameters into a WebRequest?

For doing FORM posts, the best way is to use WebClient.UploadValues() with a POST method.

How to add an element to Array and shift indexes?

org.apache.commons.lang3.ArrayUtils#add(T[], int, T) is deprecated in newest commons lang3, you can use org.apache.commons.lang3.ArrayUtils#insert(int, T[], T...) instead.

Deprecated this method has been superseded by insert(int, T[], T...) and may be removed in a future release. Please note the handling of null input arrays differs in the new method: inserting X into a null array results in null not X

Sample code:

            (4, new int[]{1, 2, 3, 4, 5, 6}, 87), new int[]{1, 2, 3, 4, 87, 5, 6});

How to get content body from a httpclient call?

If you are not wanting to use async you can add .Result to force the code to execute synchronously:

private string GetResponseString(string text)
    var httpClient = new HttpClient();

    var parameters = new Dictionary<string, string>();
    parameters["text"] = text;

    var response = httpClient.PostAsync(BaseUri, new FormUrlEncodedContent(parameters)).Result;
    var contents = response.Content.ReadAsStringAsync().Result;

    return contents;

How to add "Maven Managed Dependencies" library in build path eclipse?

If you use an eclipse plugin to do your maven tasks (there are 2 of them : M2ecipse from sonatype the 'official' one and q4e on Google Code) then, there are options in the contextual menus (right click on the project) to do that painlessly.

You can have both plugins running at the same time in your eclipse workbench and use them indifferently on a per project basis.

Return multiple values to a method caller

There is many way; but if you don't want to create a new Object or structure or something like this you can do like below after C# 7.0 :

 (string firstName, string lastName) GetName(string myParameter)
        var firstName = myParameter;
        var lastName = myParameter + " something";
        return (firstName, lastName);

    void DoSomethingWithNames()
        var (firstName, lastName) = GetName("myname");


How do I run a bat file in the background from another bat file?

Actually, the following works fine for me and creates new windows:


@echo off
start test2.cmd
start test3.cmd
echo Foo


@echo off
echo Test 2


@echo off
echo Test 3

Combine that with parameters to start, such as /min, as Moshe pointed out if you don't want the new windows to spawn in front of you.

Can a shell script set environment variables of the calling shell?

In my .bash_profile I have :

# No Proxy
function noproxy
    /usr/local/sbin/noproxy  #turn off proxy server
    unset http_proxy HTTP_PROXY https_proxy HTTPs_PROXY

# Proxy
function setproxy
    sh /usr/local/sbin/proxyon  #turn on proxy server 
    export http_proxy https_proxy HTTP_PROXY HTTPS_PROXY

So when I want to disable the proxy, the function(s) run in the login shell and sets the variables as expected and wanted.

Get column value length, not column max length of value

LENGTH() does return the string length (just verified). I suppose that your data is padded with blanks - try

SELECT typ, LENGTH(TRIM(t1.typ))


As OraNob mentioned, another cause could be that CHAR is used in which case LENGTH() would also return the column width, not the string length. However, the TRIM() approach also works in this case.

error: pathspec 'test-branch' did not match any file(s) known to git


To fix it you need to fetch first

$ git fetch origin

$ git rebase origin/master

Current branch master is up to date.

$ git checkout develop

Branch develop set up to track remote branch develop from origin.

Switched to a new branch ‘develop’

How different is Scrum practice from Agile Practice?

Scrum comes under bigger umbrella called Agile. Kanban, eXtreme Programming (XP), Lean are said to come under Agile too.

My personal experience is: there is no separate word called "Agile Practice". Best practices exercised in SCRUM, XP may be cumulatively called as Agile Practice.

The following practices are visible in both XP and SCRUM, hence in Agile.

  1. User Story as Client requirement
  2. Pair Programming
  3. Test Driven Development (TDD)
  4. Team based estimation
  5. Refactoring
  6. Simple Design
  7. Evolutionary Design
  8. Retrospective
  9. Daily Stand up meeting
  10. Continuous Integration of code
  11. Client Demo etc.

For more details, you may wish to go through my blog:

How to get the previous URL in JavaScript?

If you are writing a web app or single page application (SPA) where routing takes place in the app/browser rather than a round-trip to the server, you can do the following:

window.history.pushState({ prevUrl: window.location.href }, null, "/new/path/in/your/app")

Then, in your new route, you can do the following to retrieve the previous URL:

window.history.state.prevUrl // your previous url

A select query selecting a select statement

Not sure if Access supports it, but in most engines (including SQL Server) this is called a correlated subquery and works fine:

SELECT  TypesAndBread.Type, TypesAndBread.TBName,
        SELECT  Count(Sandwiches.[SandwichID]) As SandwichCount
        FROM    Sandwiches
        WHERE   (Type = 'Sandwich Type' AND Sandwiches.Type = TypesAndBread.TBName)
                OR (Type = 'Bread' AND Sandwiches.Bread = TypesAndBread.TBName)
        ) As SandwichCount
FROM    TypesAndBread

This can be made more efficient by indexing Type and Bread and distributing the subqueries over the UNION:

SELECT  [Sandwiches Types].[Sandwich Type] As TBName, "Sandwich Type" As Type,
        SELECT  COUNT(*) As SandwichCount
        FROM    Sandwiches
        WHERE   Sandwiches.Type = [Sandwiches Types].[Sandwich Type]
FROM    [Sandwiches Types]
SELECT  [Breads].[Bread] As TBName, "Bread" As Type,
        SELECT  COUNT(*) As SandwichCount
        FROM    Sandwiches
        WHERE   Sandwiches.Bread = [Breads].[Bread]
FROM    [Breads]

C# create simple xml file

I'd recommend serialization,

public class Person
      public  string FirstName;
      public  string MI;
      public  string LastName;

static void Serialize()
      clsPerson p = new Person();
      p.FirstName = "Jeff";
      p.MI = "A";
      p.LastName = "Price";
      System.Xml.Serialization.XmlSerializer x = new System.Xml.Serialization.XmlSerializer(p.GetType());
      x.Serialize(System.Console.Out, p);
      System.Console.WriteLine(" --- Press any key to continue --- ");

You can further control serialization with attributes.
But if it is simple, you could use XmlDocument:

using System;
using System.Xml;

public class GenerateXml {
    private static void Main() {
        XmlDocument doc = new XmlDocument();
        XmlNode docNode = doc.CreateXmlDeclaration("1.0", "UTF-8", null);

        XmlNode productsNode = doc.CreateElement("products");

        XmlNode productNode = doc.CreateElement("product");
        XmlAttribute productAttribute = doc.CreateAttribute("id");
        productAttribute.Value = "01";

        XmlNode nameNode = doc.CreateElement("Name");
        XmlNode priceNode = doc.CreateElement("Price");

        // Create and add another product node.
        productNode = doc.CreateElement("product");
        productAttribute = doc.CreateAttribute("id");
        productAttribute.Value = "02";
        nameNode = doc.CreateElement("Name");
        priceNode = doc.CreateElement("Price");


And if it needs to be fast, use XmlWriter:

public static void WriteXML()
    // Create an XmlWriterSettings object with the correct options.
    System.Xml.XmlWriterSettings settings = new System.Xml.XmlWriterSettings();
    settings.Indent = true;
    settings.IndentChars = "    "; //  "\t";
    settings.OmitXmlDeclaration = false;
    settings.Encoding = System.Text.Encoding.UTF8;

    using (System.Xml.XmlWriter writer = System.Xml.XmlWriter.Create("data.xml", settings))


        for (int i = 0; i < 100; ++i)
            writer.WriteElementString("item", "Book "+ (i+1).ToString());


    } // End Using writer 


And btw, the fastest way to read XML is XmlReader:

public static void ReadXML()
    using (System.Xml.XmlReader xmlReader = System.Xml.XmlReader.Create(""))
        while (xmlReader.Read())
            if ((xmlReader.NodeType == System.Xml.XmlNodeType.Element) && (xmlReader.Name == "Cube"))
                if (xmlReader.HasAttributes)
                    System.Console.WriteLine(xmlReader.GetAttribute("currency") + ": " + xmlReader.GetAttribute("rate"));

        } // Whend 

    } // End Using xmlReader


And the most convenient way to read XML is to just deserialize the XML into a class.
This also works for creating the serialization classes, btw.
You can generate the class from XML with Xml2CSharp:

Preloading @font-face fonts?

Your head should include the preload rel as follows:

    <link rel="preload" as="font" href="/somefolder/font-one.woff2">
    <link rel="preload" as="font" href="/somefolder/font-two.woff2">

This way woff2 will be preloaded by browsers that support preload, and all the fallback formats will load as they normally do.
And your css font face should look similar to to this

@font-face {
    font-family: FontOne;
    src: url(../somefolder/font-one.eot);
    src: url(../somefolder/font-one.eot?#iefix) format('embedded-opentype'),
    url(../somefolder/font-one.woff2) format('woff2'), //Will be preloaded
    url(../somefolder/font-one.woff) format('woff'),
    url(../somefolder/font-one.ttf)  format('truetype'),
    url(../somefolder/font-one.svg#svgFontName) format('svg'); 
@font-face {
    font-family: FontTwo;
    src: url(../somefolder/font-two.eot);
    src: url(../somefolder/font-two.eot?#iefix) format('embedded-opentype'),
    url(../somefolder/font-two.woff2) format('woff2'), //Will be preloaded
    url(../somefolder/font-two.woff) format('woff'),
    url(../somefolder/font-two.ttf)  format('truetype'),
    url(../somefolder/font-two.svg#svgFontName) format('svg');

Error in your SQL syntax; check the manual that corresponds to your MySQL server version

Some special characters give this type of error, so use

$query="INSERT INTO `tablename` (`name`, `email`)

PostgreSQL DISTINCT ON with different ORDER BY

A subquery can solve it:

    SELECT DISTINCT ON (address_id) *
    FROM   purchases
    WHERE  product_id = 1
    ) p
ORDER  BY purchased_at DESC;

Leading expressions in ORDER BY have to agree with columns in DISTINCT ON, so you can't order by different columns in the same SELECT.

Only use an additional ORDER BY in the subquery if you want to pick a particular row from each set:

    SELECT DISTINCT ON (address_id) *
    FROM   purchases
    WHERE  product_id = 1
    ORDER  BY address_id, purchased_at DESC  -- get "latest" row per address_id
    ) p
ORDER  BY purchased_at DESC;

If purchased_at can be NULL, use DESC NULLS LAST - and match your index for best performance. See:

Related, with more explanation:

How to make GREP select only numeric values?

How about:

df . -B MB | tail -1 | awk {'print $4'} | cut -d'%' -f1

Run a single test method with maven

As of surefire plugin version 2.22.1 (possibly earlier) you can run single test using testnames property when using testng.xml

Given a following testng.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "">
<suite name="Suite">
    <test name="all-tests">
            <class name="server.Atest"/>
            <class name="server.Btest"/>
            <class name="server.Ctest"/>
    <test name="run-A-test">
            <class name="server.Atest"/>
    <test name="run-B-test">
            <class name="server.Btest"/>
    <test name="run-C-test">
            <class name="server.Ctest"/>

with the pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="" xmlns:xsi="" xsi:schemaLocation="">

From command line

mvn clean test -DselectedTests=run-B-test

Further reading - Maven surefire plugin using testng

Constants in Kotlin -- what's a recommended way to create them?

Kotlin static and constant value & method declare

object MyConstant {

@JvmField   // for access in java code 
val PI: Double = 3.14

@JvmStatic // JvmStatic annotation for access in java code
fun sumValue(v1: Int, v2: Int): Int {
    return v1 + v2


Access value anywhere

val value = MyConstant.PI
val value = MyConstant.sumValue(10,5)

With jQuery, how do I capitalize the first letter of a text field while the user is still editing that field?

A turkish one. If someone is still interested.

 $('input[type="text"]').keyup(function() {
    $(this).val($(this).val().replace(/^([a-zA-Z\s\ö\ç\s\i\i\g\ü\Ö\Ç\S\I\G\Ü])|\s+([a-zA-Z\s\ö\ç\s\i\i\g\ü\Ö\Ç\S\I\G\Ü])/g, function ($1) {
        if ($1 == "i")
            return "I";
        else if ($1 == " i")
            return " I";
        return $1.toUpperCase();

How to fix apt-get: command not found on AWS EC2?

Try replacing apt-get with yum as Amazon Linux based AMI uses the yum command instead of apt-get.

HTTP Request in Kotlin

Without adding additional dependencies, this works. You don't need Volley for this. This works using the current version of Kotlin as of Dec 2018: Kotlin 1.3.10

If using Android Studio, you'll need to add this declaration in your AndroidManifest.xml:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

You should manually declare imports here. The auto-import tool caused me many conflicts.:

import android.os.AsyncTask

You can't perform network requests on a background thread. You must subclass AsyncTask.

To call the method:

NetworkTask().execute(requestURL, queryString)


private class NetworkTask : AsyncTask<String, Int, Long>() {
    override fun doInBackground(vararg parts: String): Long? {
        val requestURL = parts.first()
        val queryString = parts.last()

        // Set up request
        val connection: HttpsURLConnection = URL(requestURL).openConnection() as HttpsURLConnection
        // Default is GET so you must override this for post
        connection.requestMethod = "POST"
        // To send a post body, output must be true
        connection.doOutput = true
        // Create the stream
        val outputStream: OutputStream = connection.outputStream
        // Create a writer container to pass the output over the stream
        val outputWriter = OutputStreamWriter(outputStream)
        // Add the string to the writer container
        // Send the data

        // Create an input stream to read the response
        val inputStream = BufferedReader(InputStreamReader(connection.inputStream)).use {
            // Container for input stream data
            val response = StringBuffer()
            var inputLine = it.readLine()
            // Add each line to the response container
            while (inputLine != null) {
                inputLine = it.readLine()
            // TODO: Add main thread callback to parse response
            println(">>>> Response: $response")

        return 0

    protected fun onProgressUpdate(vararg progress: Int) {

    override fun onPostExecute(result: Long?) {

Python to print out status bar and percentage

based on the above answers and other similar questions about CLI progress bar, I think I got a general common answer to all of them. Check it at

Here is a copy of the function, but modified to fit your style:

import time, sys

# update_progress() : Displays or updates a console progress bar
## Accepts a float between 0 and 1. Any int will be converted to a float.
## A value under 0 represents a 'halt'.
## A value at 1 or bigger represents 100%
def update_progress(progress):
    barLength = 20 # Modify this to change the length of the progress bar
    status = ""
    if isinstance(progress, int):
        progress = float(progress)
    if not isinstance(progress, float):
        progress = 0
        status = "error: progress var must be float\r\n"
    if progress < 0:
        progress = 0
        status = "Halt...\r\n"
    if progress >= 1:
        progress = 1
        status = "Done...\r\n"
    block = int(round(barLength*progress))
    text = "\rPercent: [{0}] {1}% {2}".format( "="*block + " "*(barLength-block), progress*100, status)

Looks like

Percent: [====================] 99.0%

Unexpected 'else' in "else" error

You need to rearrange your curly brackets. Your first statement is complete, so R interprets it as such and produces syntax errors on the other lines. Your code should look like:

if (dsnt<0.05) {
} else if (dst<0.05) {
} else {

To put it more simply, if you have:

if(condition == TRUE) x <- TRUE
else x <- FALSE

Then R reads the first line and because it is complete, runs that in its entirety. When it gets to the next line, it goes "Else? Else what?" because it is a completely new statement. To have R interpret the else as part of the preceding if statement, you must have curly brackets to tell R that you aren't yet finished:

if(condition == TRUE) {x <- TRUE
 } else {x <- FALSE}

Emulating a do-while loop in Bash

Two simple solutions:

  1. Execute your code once before the while loop

    actions() {
       # Do other stuff
    actions #1st execution
    while [ current_time <= $cutoff ]; do
       actions # Loop execution
  2. Or:

    while : ; do
        [[ current_time <= $cutoff ]] || break

Python - Module Not Found

I had same error. For those who run python scripts on different servers, please check if the python path is correctly specified in shebang. For me on each server it was located in different dirs.

What's the best way to store a group of constants that my program uses?

IMO using a class full of constants is fine for constants. If they will change semi-occasionally I recommend using AppSettings in your config and the ConfigurationManager class instead.

When I have "constants" that are actually pulled in from AppSettings or similar I still will always have a "constants" class that wraps the reading from configuration manager. It's always more meaningful to have Constants.SomeModule.Setting instead of having to resort directly to ConfigurationManager.AppSettings["SomeModule/Setting"] on any place that wants to consume said setting value.

Bonus points for this setup, since SomeModule would likely be a nested class inside the Constants file, you could easily use Dependency Injection to inject either SomeModule directly into classes that depend on it. You could also even extract an interface on top of SomeModule and then create a depenedency to ISomeModuleConfiguration in your consuming code, this would then allow you to decouple the dependency to the Constants files, and even potentially make testing easier, especially if these settings come from AppSettings and you change them using config transformations because the settings are environment specific.

Cannot implicitly convert type 'string' to 'System.Threading.Tasks.Task<string>'

Use FromResult Method

public async Task<string> GetString()
   return await Task.FromResult("Hello");

Import SQL file by command line in Windows 7

To import SQL file what works for me

For Wamp-Server

  1. Find mysql in wamp. In my computer it's location is "C:\wamp64\bin\mysql\mysql5.7.21\bin"

Open cmd and once you get inside bin you have to write " mysql -uroot -p database_name < filename.sql"

remember to put sql file under bin.

in nutshell you have to do this:-

C:\wamp64\bin\mysql\mysql5.7.21\bin>mysql -uroot -p database_name < filename.sql

After this, it will ask for the password, mine password was nothing(BLANK).

hope it helps someone.

Oracle 10g: Extract data (select) from XML (CLOB Type)

In case of :

<?xml version="1.0" encoding="iso-8859-1"?>
<info xmlns="http://namespaces.default" xmlns:ns2="http://namespaces.ns2" >
    <id> 954 </id>
    <idboss> 954 </idboss>
    <name> Fausto </name>
    <sorname> Anonimo </sorname>
    <phone> 040000000 </phone>
    <fax> 040000001 </fax>

Query :

Select *
from xmltable(xmlnamespaces(default 'http://namespaces.default'
                              'http://namespaces.ns2' as "ns",
                passing xmltype.createxml(xml) 
                columns id varchar2(10) path '/id',
                        idboss varchar2(500) path '/idboss',

                ) nice_xml_table

How do I check if an integer is even or odd?

I would build a table of the parities (0 if even 1 if odd) of the integers (so one could do a lookup :D), but gcc won't let me make arrays of such sizes:

typedef unsigned int uint;

char parity_uint [UINT_MAX];
char parity_sint_shifted [((uint) INT_MAX) + ((uint) abs (INT_MIN))];
char* parity_sint = parity_sint_shifted - INT_MIN;

void build_parity_tables () {
    char parity = 0;
    unsigned int ui;
    for (ui = 1; ui <= UINT_MAX; ++ui) {
        parity_uint [ui - 1] = parity;
        parity = !parity;
    parity = 0;
    int si;
    for (si = 1; si <= INT_MAX; ++si) {
        parity_sint [si - 1] = parity;
        parity = !parity;
    parity = 1;
    for (si = -1; si >= INT_MIN; --si) {
        parity_sint [si] = parity;
        parity = !parity;

char uparity (unsigned int n) {
    if (n == 0) {
        return 0;
    return parity_uint [n - 1];

char sparity (int n) {
    if (n == 0) {
        return 0;
    if (n < 0) {
    return parity_sint [n - 1];

So let's instead resort to the mathematical definition of even and odd instead.

An integer n is even if there exists an integer k such that n = 2k.

An integer n is odd if there exists an integer k such that n = 2k + 1.

Here's the code for it:

char even (int n) {
    int k;
    for (k = INT_MIN; k <= INT_MAX; ++k) {
        if (n == 2 * k) {
            return 1;
    return 0;

char odd (int n) {
    int k;
    for (k = INT_MIN; k <= INT_MAX; ++k) {
        if (n == 2 * k + 1) {
            return 1;
    return 0;

Let C-integers denote the possible values of int in a given C compilation. (Note that C-integers is a subset of the integers.)

Now one might worry that for a given n in C-integers that the corresponding integer k might not exist within C-integers. But with a little proof it is can be shown that for all integers n, |n| <= |2n| (*), where |n| is "n if n is positive and -n otherwise". In other words, for all n in integers at least one of the following holds (exactly either cases (1 and 2) or cases (3 and 4) in fact but I won't prove it here):

Case 1: n <= 2n.

Case 2: -n <= -2n.

Case 3: -n <= 2n.

Case 4: n <= -2n.

Now take 2k = n. (Such a k does exist if n is even, but I won't prove it here. If n is not even then the loop in even fails to return early anyway, so it doesn't matter.) But this implies k < n if n not 0 by (*) and the fact (again not proven here) that for all m, z in integers 2m = z implies z not equal to m given m is not 0. In the case n is 0, 2*0 = 0 so 0 is even we are done (if n = 0 then 0 is in C-integers because n is in C-integer in the function even, hence k = 0 is in C-integers). Thus such a k in C-integers exists for n in C-integers if n is even.

A similar argument shows that if n is odd, there exists a k in C-integers such that n = 2k + 1.

Hence the functions even and odd presented here will work properly for all C-integers.

Official way to ask jQuery wait for all images to load before executing something

Use imagesLoaded PACKAGED v3.1.8 (6.8 Kb when minimized). It is relatively old (since 2010) but still active project.

You can find it on github:

Their official site:

Why it is better than using:


Because you may want to load images dynamically, like this: jsfiddle

    $('#image').attr('src', '...');

PHP Fatal error: Class 'PDO' not found

I had the same problem on GoDaddy. I added the to php.ini, still didn't work. And then only one thing came to my mind: Permissions

Before uploading the file, kill all PHP processes(cPanel->PHP Processes).

The problem was that with the file permissions, it was set to 0644 and was not executable . You need to set the file permission at least 0755.


Run JavaScript in Visual Studio Code

I am surprised this has not been mentioned yet:

Simply open the .js file in question in VS Code, switch to the 'Debug Console' tab, hit the debug button in the left nav bar, and click the run icon (play button)!

Requires nodejs to be installed!

Parse a URI String into Name-Value Collection

Netty also provides a nice query string parser called QueryStringDecoder. In one line of code, it can parse the URL in the question. I like because it doesn't require catching or throwing

In one line:

Map<String, List<String>> parameters = new QueryStringDecoder(url).parameters();

See javadocs here:

Here is a short, self contained, correct example:

import io.netty.handler.codec.http.QueryStringDecoder;
import org.apache.commons.lang3.StringUtils;

import java.util.List;
import java.util.Map;

public class UrlParse {

  public static void main(String... args) {
    String url = "";
    QueryStringDecoder decoder = new QueryStringDecoder(url);
    Map<String, List<String>> parameters = decoder.parameters();

  private static void print(final Map<String, List<String>> parameters) {
    System.out.println("NAME               VALUE");
    parameters.forEach((key, values) ->
        values.forEach(val ->
            System.out.println(StringUtils.rightPad(key, 19) + val)));

which generates

NAME               VALUE
client_id          SS
response_type      code
scope              N_FULL
access_type        offline
redirect_uri       http://localhost/Callback

Mercurial — revert back to old version and continue from there

The answers above were most useful and I learned a lot. However, for my needs the succinct answer is:

hg revert --all --rev ${1}

hg commit -m "Restoring branch ${1} as default"

where ${1} is the number of the revision or the name of the branch. These two lines are actually part of a bash script, but they work fine on their own if you want to do it manually.

This is useful if you need to add a hot fix to a release branch, but need to build from default (until we get our CI tools right and able to build from branches and later do away with release branches as well).

Request failed: unacceptable content-type: text/html using AFNetworking 2.0

Just add this line :

operation.responseSerializer.acceptableContentTypes = [NSSet setWithObject:@"text/html"];

How do I find which process is leaking memory?

I suggest the use of htop, as a better alternative to top.

How can I add a line to a file in a shell script?

This doesn't use sed, but using >> will append to a file. For example:

echo 'one, two, three' >> testfile.csv

Edit: To prepend to a file, try something like this:

echo "text"|cat - yourfile > /tmp/out && mv /tmp/out yourfile

I found this through a quick Google search.

When and why do I need to use cin.ignore() in C++?

Ignore function is used to skip(discard/throw away) characters in the input stream. Ignore file is associated with the file istream. Consider the function below ex: cin.ignore(120,'/n'); the particular function skips the next 120 input character or to skip the characters until a newline character is read.

What does jQuery.fn mean?

fn literally refers to the jquery prototype.

This line of code is in the source code:

jQuery.fn = jQuery.prototype = {
 //list of functions available to the jQuery api

But the real tool behind fn is its availability to hook your own functionality into jQuery. Remember that jquery will be the parent scope to your function, so this will refer to the jquery object.

$.fn.myExtension = function(){
 var currentjQueryObject = this;
 //work with currentObject
 return this;//you can include this if you would like to support chaining

So here is a simple example of that. Lets say I want to make two extensions, one which puts a blue border, and which colors the text blue, and I want them chained.

jsFiddle Demo

$.fn.blueBorder = function(){
  $(this).css("border","solid blue 2px");
 return this;
$.fn.blueText = function(){
 return this;

Now you can use those against a class like this:


(I know this is best done with css such as applying different class names, but please keep in mind this is just a demo to show the concept)

This answer has a good example of a full fledged extension.

Regex to remove letters, symbols except numbers

If you want to keep only numbers then use /[^0-9]+/ instead of /[^a-zA-Z]+/

"use database_name" command in PostgreSQL

In pgAdmin you can also use

SET search_path TO your_db_name;

Could not find a declaration file for module 'module-name'. '/path/to/module-name.js' implicitly has an 'any' type

TypeScript is basically implementing rules and adding types to your code to make it more clear and more accurate due to the lack of constraints in Javascript. TypeScript requires you to describe your data, so that the compiler can check your code and find errors. The compiler will let you know if you are using mismatched types, if you are out of your scope or you try to return a different type. So, when you are using external libraries and modules with TypeScript, they need to contain files that describe the types in that code. Those files are called type declaration files with an extension d.ts. Most of the declaration types for npm modules are already written and you can include them using npm install @types/module_name (where module_name is the name of the module whose types you wanna include).

However, there are modules that don't have their type definitions and in order to make the error go away and import the module using import * as module_name from 'module-name', create a folder typings in the root of your project, inside create a new folder with your module name and in that folder create a module_name.d.ts file and write declare module 'module_name'. After this just go to your tsconfig.json file and add "typeRoots": [ "../../typings", "../../node_modules/@types"] in the compilerOptions (with the proper relative path to your folders) to let TypeScript know where it can find the types definitions of your libraries and modules and add a new property "exclude": ["../../node_modules", "../../typings"] to the file. Here is an example of how your tsconfig.json file should look like:

    "compilerOptions": {
        "module": "commonjs",
        "noImplicitAny": true,
        "sourceMap": true,
        "outDir": "../dst/",
        "target": "ESNEXT",
        "typeRoots": [
    "lib": [
    "exclude": [

By doing this, the error will go away and you will be able to stick to the latest ES6 and TypeScript rules.

Change status bar color with AppCompat ActionBarActivity

[Kotlin version] I created this extension that also checks if the desired color has enough contrast to hide the System UI, like Battery Status Icon, Clock, etc, so we set the System UI white or black according to this.

fun Activity.coloredStatusBarMode(@ColorInt color: Int = Color.WHITE, lightSystemUI: Boolean? = null) {
    var flags: Int = window.decorView.systemUiVisibility // get current flags
    var systemLightUIFlag = View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR
    var setSystemUILight = lightSystemUI

    if (setSystemUILight == null) {
        // Automatically check if the desired status bar is dark or light
        setSystemUILight = ColorUtils.calculateLuminance(color) < 0.5

    flags = if (setSystemUILight) {
        // Set System UI Light (Battery Status Icon, Clock, etc)
        removeFlag(flags, systemLightUIFlag)
    } else {
        // Set System UI Dark (Battery Status Icon, Clock, etc)
        addFlag(flags, systemLightUIFlag)

    window.decorView.systemUiVisibility = flags
    window.statusBarColor = color

private fun containsFlag(flags: Int, flagToCheck: Int) = (flags and flagToCheck) != 0

private fun addFlag(flags: Int, flagToAdd: Int): Int {
    return if (!containsFlag(flags, flagToAdd)) {
        flags or flagToAdd
    } else {

private fun removeFlag(flags: Int, flagToRemove: Int): Int {
    return if (containsFlag(flags, flagToRemove)) {
        flags and flagToRemove.inv()
    } else {

How are people unit testing with Entity Framework 6, should you bother?

I want to share an approach commented about and briefly discussed but show an actual example that I am currently using to help unit test EF-based services.

First, I would love to use the in-memory provider from EF Core, but this is about EF 6. Furthermore, for other storage systems like RavenDB, I'd also be a proponent of testing via the in-memory database provider. Again--this is specifically to help test EF-based code without a lot of ceremony.

Here are the goals I had when coming up with a pattern:

  • It must be simple for other developers on the team to understand
  • It must isolate the EF code at the barest possible level
  • It must not involve creating weird multi-responsibility interfaces (such as a "generic" or "typical" repository pattern)
  • It must be easy to configure and setup in a unit test

I agree with previous statements that EF is still an implementation detail and it's okay to feel like you need to abstract it in order to do a "pure" unit test. I also agree that ideally, I would want to ensure the EF code itself works--but this involves a sandbox database, in-memory provider, etc. My approach solves both problems--you can safely unit test EF-dependent code and create integration tests to test your EF code specifically.

The way I achieved this was through simply encapsulating EF code into dedicated Query and Command classes. The idea is simple: just wrap any EF code in a class and depend on an interface in the classes that would've originally used it. The main issue I needed to solve was to avoid adding numerous dependencies to classes and setting up a lot of code in my tests.

This is where a useful, simple library comes in: Mediatr. It allows for simple in-process messaging and it does it by decoupling "requests" from the handlers that implement the code. This has an added benefit of decoupling the "what" from the "how". For example, by encapsulating the EF code into small chunks it allows you to replace the implementations with another provider or totally different mechanism, because all you are doing is sending a request to perform an action.

Utilizing dependency injection (with or without a framework--your preference), we can easily mock the mediator and control the request/response mechanisms to enable unit testing EF code.

First, let's say we have a service that has business logic we need to test:

public class FeatureService {

  private readonly IMediator _mediator;

  public FeatureService(IMediator mediator) {
    _mediator = mediator;

  public async Task ComplexBusinessLogic() {
    // retrieve relevant objects

    var results = await _mediator.Send(new GetRelevantDbObjectsQuery());
    // normally, this would have looked like...
    // var results = _myDbContext.DbObjects.Where(x => foo).ToList();

    // perform business logic
    // ...    

Do you start to see the benefit of this approach? Not only are you explicitly encapsulating all EF-related code into descriptive classes, you are allowing extensibility by removing the implementation concern of "how" this request is handled--this class doesn't care if the relevant objects come from EF, MongoDB, or a text file.

Now for the request and handler, via MediatR:

public class GetRelevantDbObjectsQuery : IRequest<DbObject[]> {
  // no input needed for this particular request,
  // but you would simply add plain properties here if needed

public class GetRelevantDbObjectsEFQueryHandler : IRequestHandler<GetRelevantDbObjectsQuery, DbObject[]> {
  private readonly IDbContext _db;

  public GetRelevantDbObjectsEFQueryHandler(IDbContext db) {
    _db = db;

  public DbObject[] Handle(GetRelevantDbObjectsQuery message) {
    return _db.DbObjects.Where(foo => bar).ToList();

As you can see, the abstraction is simple and encapsulated. It's also absolutely testable because in an integration test, you could test this class individually--there are no business concerns mixed in here.

So what does a unit test of our feature service look like? It's way simple. In this case, I'm using Moq to do mocking (use whatever makes you happy):

public class FeatureServiceTests {

  // mock of Mediator to handle request/responses
  private Mock<IMediator> _mediator;

  // subject under test
  private FeatureService _sut;

  public void Setup() {

    // set up Mediator mock
    _mediator = new Mock<IMediator>(MockBehavior.Strict);

    // inject mock as dependency
    _sut = new FeatureService(_mediator.Object);

  public void Teardown() {

    // ensure we have called or expected all calls to Mediator

  public void ComplexBusinessLogic_Does_What_I_Expect() {
    var dbObjects = new List<DbObject>() {
      // set up any test objects
      new DbObject() { }

    // arrange

    // setup Mediator to return our fake objects when it receives a message to perform our query
    // in practice, I find it better to create an extension method that encapsulates this setup here
    _mediator.Setup(x => x.Send(It.IsAny<GetRelevantDbObjectsQuery>(), default(CancellationToken)).ReturnsAsync(dbObjects.ToArray()).Callback(
    (GetRelevantDbObjectsQuery message, CancellationToken token) => {
       // using Moq Callback functionality, you can make assertions
       // on expected request being passed in

    // act

    // assertions


You can see all we need is a single setup and we don't even need to configure anything extra--it's a very simple unit test. Let's be clear: This is totally possible to do without something like Mediatr (you would simply implement an interface and mock it for tests, e.g. IGetRelevantDbObjectsQuery), but in practice for a large codebase with many features and queries/commands, I love the encapsulation and innate DI support Mediatr offers.

If you're wondering how I organize these classes, it's pretty simple:

- MyProject
  - Features
    - MyFeature
      - Queries
      - Commands
      - Services
      - DependencyConfig.cs (Ninject feature modules)

Organizing by feature slices is beside the point, but this keeps all relevant/dependent code together and easily discoverable. Most importantly, I separate the Queries vs. Commands--following the Command/Query Separation principle.

This meets all my criteria: it's low-ceremony, it's easy to understand, and there are extra hidden benefits. For example, how do you handle saving changes? Now you can simplify your Db Context by using a role interface (IUnitOfWork.SaveChangesAsync()) and mock calls to the single role interface or you could encapsulate committing/rolling back inside your RequestHandlers--however you prefer to do it is up to you, as long as it's maintainable. For example, I was tempted to create a single generic request/handler where you'd just pass an EF object and it would save/update/remove it--but you have to ask what your intention is and remember that if you wanted to swap out the handler with another storage provider/implementation, you should probably create explicit commands/queries that represent what you intend to do. More often than not, a single service or feature will need something specific--don't create generic stuff before you have a need for it.

There are of course caveats to this pattern--you can go too far with a simple pub/sub mechanism. I've limited my implementation to only abstracting EF-related code, but adventurous developers could start using MediatR to go overboard and message-ize everything--something good code review practices and peer reviews should catch. That's a process issue, not an issue with MediatR, so just be cognizant of how you're using this pattern.

You wanted a concrete example of how people are unit testing/mocking EF and this is an approach that's working successfully for us on our project--and the team is super happy with how easy it is to adopt. I hope this helps! As with all things in programming, there are multiple approaches and it all depends on what you want to achieve. I value simplicity, ease of use, maintainability, and discoverability--and this solution meets all those demands.

How do I measure separate CPU core usage for a process?

The ps solution was nearly what I needed and with some bash thrown in does exactly what the original question asked for: to see per-core usage of specific processes

This shows per-core usage of multi-threaded processes too.

Use like: cpustat `pgrep processname` `pgrep otherprocessname` ...


while [ $# != 0 ]; do
        pids=("${pids[@]}" "$1")

if [ -z "${pids[0]}" ]; then
        echo "Usage: $0 <pid1> [pid2] ..."
        exit 1

for pid in "${pids[@]}"; do
        if [ ! -e /proc/$pid ]; then
                echo "Error: pid $pid doesn't exist"
                exit 1

while [ true ]; do
        echo -e "\033[H\033[J"
        for pid in "${pids[@]}"; do
                ps -p $pid -L -o pid,tid,psr,pcpu,comm=
        sleep 1

Note: These stats are based on process lifetime, not the last X seconds, so you'll need to restart your process to reset the counter.

Powershell's Get-date: How to get Yesterday at 22:00 in a variable?

I saw in at least one other place that people don't realize Date-Time takes in times as well, so I figured I'd share it here since it's really short to do so:

Get-Date # Following the OP's example, let's say it's Friday, March 12, 2010 9:00:00 AM
(Get-Date '22:00').AddDays(-1) # Thursday, March 11, 2010 10:00:00 PM

It's also the shortest way to strip time information and still use other parameters of Get-Date. For instance you can get seconds since 1970 this way (Unix timestamp):

Get-Date '0:00' -u '%s' # 1268352000

Or you can get an ISO 8601 timestamp:

Get-Date '0:00' -f 's' # 2010-03-12T00:00:00

Then again if you reverse the operands, it gives you a little more freedom with formatting with any date object:

'The sortable timestamp: {0:s}Z{1}Vs measly human format: {0:D}' -f (Get-Date '0:00'), "`r`n"
# The sortable timestamp: 2010-03-12T00:00:00Z
# Vs measly human format: Friday, March 12, 2010

However if you wanted to both format a Unix timestamp (via -u aka -UFormat), you'll need to do it separately. Here's an example of that:

'ISO 8601: {0:s}Z{1}Unix: {2}' -f (Get-Date '0:00'), "`r`n", (Get-Date '0:00' -u '%s')
# ISO 8601: 2010-03-12T00:00:00Z
# Unix: 1268352000

Hope this helps!

How to read line by line of a text area HTML tag

Try this.

var lines = $('textarea').val().split('\n');
for(var i = 0;i < lines.length;i++){
    //code here using lines[i] which will give you each line

How to get column by number in Pandas?

The following is taken from There are a few more examples... you have to scroll down a little

In [816]: df1

           0         2         4         6
0   0.569605  0.875906 -2.211372  0.974466
2  -2.006747 -0.410001 -0.078638  0.545952
4  -1.219217 -1.226825  0.769804 -1.281247
6  -0.727707 -0.121306 -0.097883  0.695775
8   0.341734  0.959726 -1.110336 -0.619976
10  0.149748 -0.732339  0.687738  0.176444

Select via integer slicing

In [817]: df1.iloc[:3]

          0         2         4         6
0  0.569605  0.875906 -2.211372  0.974466
2 -2.006747 -0.410001 -0.078638  0.545952
4 -1.219217 -1.226825  0.769804 -1.281247

In [818]: df1.iloc[1:5,2:4]

          4         6
2 -0.078638  0.545952
4  0.769804 -1.281247
6 -0.097883  0.695775
8 -1.110336 -0.619976

Select via integer list

In [819]: df1.iloc[[1,3,5],[1,3]]

           2         6
2  -0.410001  0.545952
6  -0.121306  0.695775
10 -0.732339  0.176444

How do I iterate through children elements of a div using jQuery?

Use children() and each(), you can optionally pass a selector to children

$('#mydiv').children('input').each(function () {
    alert(this.value); // "this" is the current element in the loop

You could also just use the immediate child selector:

$('#mydiv > input').each(function () { /* ... */ });

Git workflow and rebase vs merge questions

Anyway, I was following my workflow on a recent branch, and when I tried to merge it back to master, it all went to hell. There were tons of conflicts with things that should have not mattered. The conflicts just made no sense to me. It took me a day to sort everything out, and eventually culminated in a forced push to the remote master, since my local master has all conflicts resolved, but the remote one still wasn't happy.

In neither your partner's nor your suggested workflows should you have come across conflicts that didn't make sense. Even if you had, if you are following the suggested workflows then after resolution a 'forced' push should not be required. It suggests that you haven't actually merged the branch to which you were pushing, but have had to push a branch that wasn't a descendent of the remote tip.

I think you need to look carefully at what happened. Could someone else have (deliberately or not) rewound the remote master branch between your creation of the local branch and the point at which you attempted to merge it back into the local branch?

Compared to many other version control systems I've found that using Git involves less fighting the tool and allows you to get to work on the problems that are fundamental to your source streams. Git doesn't perform magic, so conflicting changes cause conflicts, but it should make it easy to do the write thing by its tracking of commit parentage.

MYSQL order by both Ascending and Descending sorting

You can do that in this way:

ORDER BY `products`.`product_category_id` DESC ,`naam` ASC

Have a look at ORDER BY Optimization

node.js vs. meteor.js what's the difference?

A loose analogy is, "Meteor is to Node as Rails is to Ruby." It's a large, opinionated framework that uses Node on the server. Node itself is just a low-level framework providing functions for sending and receiving HTTP requests and performing other I/O.

Meteor is radically ambitious: By default, every page it serves is actually a Handlebars template that's kept in sync with the server. Try the Leaderboard example: You create a template that simply says "List the names and scores," and every time any client changes a name or score, the page updates with the new data—not just for that client, but for everyone viewing the page.

Another difference: While Node itself is stable and widely used in production, Meteor is in a "preview" state. There are serious bugs, and certain things that don't fit with Meteor's data-centric conceptual model (such as animations) are very hard to do.

If you love playing with new technologies, give Meteor a spin. If you want a more traditional, stable web framework built on Node, take a look at Express.

How to implement "Access-Control-Allow-Origin" header in

Configuring the CORS response headers on the server wasn't really an option. You should configure a proxy in client side.

Sample to Angular - So, I created a proxy.conf.json file to act as a proxy server. Below is my proxy.conf.json file:

  "/api": {
    "target": "http://localhost:49389",
    "secure": true,
    "pathRewrite": {
      "^/api": "/api"
    "changeOrigin": true

Put the file in the same directory the package.json then I modified the start command in the package.json file like below

"start": "ng serve --proxy-config proxy.conf.json"

now, the http call from the app component is as follows:

return this.http.get('/api/customers').map((res: Response) => res.json());

Lastly to run use npm start or ng serve --proxy-config proxy.conf.json

ApiNotActivatedMapError for simple html page using google-places-api

I had the same error. To fix the error:

  1. Open the console menu Gallery Menu and select API Manager.
  2. On the left, click Credentials and then click New Credentials.
  3. Click Create Credentials.
  4. Click API KEY.
  5. Click Navigator Key (there are more options; It depends on when consumed).

You must use this new API Navigator Key, generated by the system.

Removing duplicate characters from a string

If order does not matter, you can use


set() will create a set of unique letters in the string, and "".join() will join the letters back to a string in arbitrary order.

If order does matter, you can use a dict instead of a set, which since Python 3.7 preserves the insertion order of the keys. (In the CPython implementation, this is already supported in Python 3.6 as an implementation detail.)

foo = "mppmt"
result = "".join(dict.fromkeys(foo))

resulting in the string "mpt". In earlier versions of Python, you can use collections.OrderedDict, which has been available starting from Python 2.7.

How to check for a valid URL in Java?

I didn't like any of the implementations (because they use a Regex which is an expensive operation, or a library which is an overkill if you only need one method), so I ended up using the class with some extra checks, and limiting the protocols to: http, https, file, ftp, mailto, news, urn.

And yes, catching exceptions can be an expensive operation, but probably not as bad as Regular Expressions:

final static Set<String> protocols, protocolsWithHost;

static {
  protocolsWithHost = new HashSet<String>( 
      Arrays.asList( new String[]{ "file", "ftp", "http", "https" } ) 
  protocols = new HashSet<String>( 
      Arrays.asList( new String[]{ "mailto", "news", "urn" } ) 

public static boolean isURI(String str) {
  int colon = str.indexOf(':');
  if (colon < 3)                      return false;

  String proto = str.substring(0, colon).toLowerCase();
  if (!protocols.contains(proto))     return false;

  try {
    URI uri = new URI(str);
    if (protocolsWithHost.contains(proto)) {
      if (uri.getHost() == null)      return false;

      String path = uri.getPath();
      if (path != null) {
        for (int i=path.length()-1; i >= 0; i--) {
          if ("?<>:*|\"".indexOf( path.charAt(i) ) > -1)
            return false;

    return true;
  } catch ( Exception ex ) {}

  return false;

How to change icon on Google map marker

You have to add the targeted map :

var markers = [
            "title": 'This is title',
            "lat": '-37.801578',
            "lng": '145.060508',
            "map":  map,
            "icon": '',
            "description": 'Vikash Rathee. <strong> This is test Description</strong> <br/><a href="">Pin Code by 


Jest spyOn function called

You were almost done without any changes besides how you spyOn. When you use the spy, you have two options: spyOn the App.prototype, or component component.instance().

const spy = jest.spyOn(Class.prototype, "method")

The order of attaching the spy on the class prototype and rendering (shallow rendering) your instance is important.

const spy = jest.spyOn(App.prototype, "myClickFn");
const instance = shallow(<App />);

The App.prototype bit on the first line there are what you needed to make things work. A JavaScript class doesn't have any of its methods until you instantiate it with new MyClass(), or you dip into the MyClass.prototype. For your particular question, you just needed to spy on the App.prototype method myClickFn.

jest.spyOn(component.instance(), "method")

const component = shallow(<App />);
const spy = jest.spyOn(component.instance(), "myClickFn");

This method requires a shallow/render/mount instance of a React.Component to be available. Essentially spyOn is just looking for something to hijack and shove into a jest.fn(). It could be:

A plain object:

const obj = {a: x => (true)};
const spy = jest.spyOn(obj, "a");

A class:

class Foo {
    bar() {}

const nope = jest.spyOn(Foo, "bar");
// THROWS ERROR. Foo has no "bar" method.
// Only an instance of Foo has "bar".
const fooSpy = jest.spyOn(Foo.prototype, "bar");
// Any call to "bar" will trigger this spy; prototype or instance

const fooInstance = new Foo();
const fooInstanceSpy = jest.spyOn(fooInstance, "bar");
// Any call fooInstance makes to "bar" will trigger this spy.

Or a React.Component instance:

const component = shallow(<App />);
-> {myClickFn: f(), render: f(), ...etc}
const spy = jest.spyOn(component.instance(), "myClickFn");

Or a React.Component.prototype:

-> {myClickFn: f(), render: f(), ...etc}
const spy = jest.spyOn(App.prototype, "myClickFn");
// Any call to "myClickFn" from any instance of App will trigger this spy.

I've used and seen both methods. When I have a beforeEach() or beforeAll() block, I might go with the first approach. If I just need a quick spy, I'll use the second. Just mind the order of attaching the spy.

EDIT: If you want to check the side effects of your myClickFn you can just invoke it in a separate test.

const app = shallow(<App />);
Now assert your function does what it is supposed to do...

EDIT: Here is an example of using a functional component. Keep in mind that any methods scoped within your functional component are not available for spying. You would be spying on function props passed into your functional component and testing the invocation of those. This example explores the use of jest.fn() as opposed to jest.spyOn, both of which share the mock function API. While it does not answer the original question, it still provides insight on other techniques that could suit cases indirectly related to the question.

function Component({ myClickFn, items }) {
   const handleClick = (id) => {
       return () => myClickFn(id);
   return (<>
       {{id, name}) => (
           <div key={id} onClick={handleClick(id)}>{name}</div>

const props = { myClickFn: jest.fn(), items: [/*...{id, name}*/] };
const component = render(<Component {...props} />);
// Do stuff to fire a click event

Batch script loop

Template for a simple but counted loop:

set loopcount=[Number of times]
[Commands you want to repeat]
set /a loopcount=loopcount-1
if %loopcount%==0 goto exitloop
goto loop

Example: Say "Hello World!" 5 times:

@echo off
set loopcount=5
echo Hello World!
set /a loopcount=loopcount-1
if %loopcount%==0 goto exitloop
goto loop

This example will output:

Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
Press any key to continue . . .

How to scroll to an element in jQuery?



It'll scroll the window to the item.

 var scrollPos =  $("#branch1").offset().top;

JavaScript: function returning an object

The latest way to do this with ES2016 JavaScript

let makeGamePlayer = (name, totalScore, gamesPlayed) => ({

A child container failed during start java.util.concurrent.ExecutionException

check if you JAVA_HOME is set to 1.7 or below. because tomcat 7 is not compatible with jdk 1.8

This worked for me

VIM Disable Automatic Newline At End Of File

I've implemented Blixtor's suggestions with Perl and Python post-processing, either running inside Vim (if it is compiled with such language support), or via an external Perl script. It's available as the PreserveNoEOL plugin on

Using GCC to produce readable assembly?

Using the -S switch to GCC on x86 based systems produces a dump of AT&T syntax, by default, which can be specified with the -masm=att switch, like so:

gcc -S -masm=att code.c

Whereas if you'd like to produce a dump in Intel syntax, you could use the -masm=intel switch, like so:

gcc -S -masm=intel code.c

(Both produce dumps of code.c into their various syntax, into the file code.s respectively)

In order to produce similar effects with objdump, you'd want to use the --disassembler-options= intel/att switch, an example (with code dumps to illustrate the differences in syntax):

 $ objdump -d --disassembler-options=att code.c
 080483c4 <main>:
 80483c4:   8d 4c 24 04             lea    0x4(%esp),%ecx
 80483c8:   83 e4 f0                and    $0xfffffff0,%esp
 80483cb:   ff 71 fc                pushl  -0x4(%ecx)
 80483ce:   55                      push   %ebp
 80483cf:   89 e5                   mov    %esp,%ebp
 80483d1:   51                      push   %ecx
 80483d2:   83 ec 04                sub    $0x4,%esp
 80483d5:   c7 04 24 b0 84 04 08    movl   $0x80484b0,(%esp)
 80483dc:   e8 13 ff ff ff          call   80482f4 <puts@plt>
 80483e1:   b8 00 00 00 00          mov    $0x0,%eax
 80483e6:   83 c4 04                add    $0x4,%esp 
 80483e9:   59                      pop    %ecx
 80483ea:   5d                      pop    %ebp
 80483eb:   8d 61 fc                lea    -0x4(%ecx),%esp
 80483ee:   c3                      ret
 80483ef:   90                      nop


$ objdump -d --disassembler-options=intel code.c
 080483c4 <main>:
 80483c4:   8d 4c 24 04             lea    ecx,[esp+0x4]
 80483c8:   83 e4 f0                and    esp,0xfffffff0
 80483cb:   ff 71 fc                push   DWORD PTR [ecx-0x4]
 80483ce:   55                      push   ebp
 80483cf:   89 e5                   mov    ebp,esp
 80483d1:   51                      push   ecx
 80483d2:   83 ec 04                sub    esp,0x4
 80483d5:   c7 04 24 b0 84 04 08    mov    DWORD PTR [esp],0x80484b0
 80483dc:   e8 13 ff ff ff          call   80482f4 <puts@plt>
 80483e1:   b8 00 00 00 00          mov    eax,0x0
 80483e6:   83 c4 04                add    esp,0x4
 80483e9:   59                      pop    ecx
 80483ea:   5d                      pop    ebp
 80483eb:   8d 61 fc                lea    esp,[ecx-0x4]
 80483ee:   c3                      ret    
 80483ef:   90                      nop