Programs & Examples On #Ascx

The ascx is used to create or define custom usercontrols to be placed onto web pages.

Calling another different view from the controller using ASP.NET MVC 4

You have to specify the name of the custom view and its related model in Controller Action method.

public ActionResult About()
   return View("NameOfViewYouWantToReturn",Model); 

The view or its master was not found or no view engine supports the searched locations

I ran into this a while ago and it drove me crazy because it turned out to be simple. So within my View I was using a grid control that obtained data for the grid via an http request. Once the middle tier completed my request and returned the dataset, I received the same error. Turns out my return statement was 'return View(dataset);' instead of 'return Json(dataset);

jquery toggle slide from left to right and back

See this: Demo

$('#cat_icon,.panel_title').click(function () {

Update : To slide from left to right: Demo2

Note: Second one uses jquery-ui also

Why is access to the path denied?

In my case the problem was Norton. My in-house program doesn't have the proper digital signature and when it tried to delete a file it gave the UnauthorizedAccessException.

enter image description here

If it give you a notification, you can handle it from there. In my case it didn't give a notification that I noticed. So here's how to keep Norton from blocking the program.

  1. Open Norton
  2. Click the down arrow
  3. Click History
  4. Find activity by program
  5. Click More Options
  6. Click Exclude Process

How to make script execution wait until jquery is loaded

the easiest and safest way is to use something like this:

var waitForJQuery = setInterval(function () {
    if (typeof $ != 'undefined') {

        // place your code here.

}, 10);

Multiple file-extensions searchPattern for System.IO.Directory.GetFiles

var filteredFiles = Directory
    .GetFiles(path, "*.*")
    .Where(file => file.ToLower().EndsWith("aspx") || file.ToLower().EndsWith("ascx"))

Edit 2014-07-23

You can do this in .NET 4.5 for a faster enumeration:

var filteredFiles = Directory
    .EnumerateFiles(path) //<--- .NET 4.5
    .Where(file => file.ToLower().EndsWith("aspx") || file.ToLower().EndsWith("ascx"))

Directory.EnumerateFiles in MSDN

when do you need .ascx files and how would you use them?

Ascx-files are called User Controls and are meant for reusability and also for making complex aspx-pages less complex (lift out some part of the page). They could also be beneficial for something called donut caching, that is when you would like to cache a certain part of a page.

ASP.NET MVC Razor: How to render a Razor Partial View's HTML inside the controller action

great code; little hint: if you sometimes have to bypass more data and not only the viewmodel ..

 if (model is ViewDataDictionary)
     controller.ViewData = model as ViewDataDictionary;
 } else {
     controller.ViewData.Model = model;

Copy files without overwrite

Robocopy can be downloaded here for systems where it is not installed already. (I.e. Windows Server 2003.) (no reboot required for installation)

Remember to set your path to the robocopy exe. You do this by right clicking "my computer"> properties>advanced>"Environment Variables", then find the path system variable and add this to the end: ";C:\Program Files\Windows Resource Kits\Tools" or wherever you installed it. Make sure to leave the path variable strings that are already there and just append the addtional path.

once the path is set, you can run the command that belisarius suggests. It works great.

Html attributes for EditorFor() in ASP.NET MVC

Why not just use

@Html.DisplayFor(model => model.Control.PeriodType)

How to convert View Model into JSON object in ASP.NET MVC?

Well done, you've only just started using MVC and you've found its first major flaw.

You don't really want to be converting it to JSON in the view, and you don't really want to convert it in the controller, as neither of these locations make sense. Unfortunately, you're stuck with this situation.

The best thing I've found to do is send the JSON to the view in a ViewModel, like this:

var data = somedata;
var viewModel = new ViewModel();
var serializer = new JavaScriptSerializer();
viewModel.JsonData = serializer.Serialize(data);

return View("viewname", viewModel);

then use

<%= Model.JsonData %>

in your view. Be aware that the standard .NET JavaScriptSerializer is pretty crap.

doing it in the controller at least makes it testable (although not exactly like the above - you probably want to take an ISerializer as a dependency so you can mock it)

Update also, regarding your JavaScript, it would be good practice to wrap ALL the widget JS you have above like so:

    // all js here

this way if you put multiple widgets on a page, you won't get conflicts (unless you need to access the methods from elsewhere in the page, but in that case you should be registering the widget with some widget framework anyway). It may not be a problem now, but it would be good practice to add the brackets now to save yourself muchos effort in the future when it becomes a requirement, it's also good OO practice to encapsulate the functionality.

The view 'Index' or its master was not found.

Add the following code in the Application_Start() method inside your project:

ViewEngines.Engines.Add(new RazorViewEngine());

Can I set up HTML/Email Templates with ASP.NET?

What would be ideal what be to use a .ASPX page as a template somehow, then just tell my code to serve that page, and use the HTML returned for the email.

You could easily just construct a WebRequest to hit an ASPX page and get the resultant HTML. With a little more work, you can probably get it done without the WebRequest. A PageParser and a Response.Filter would allow you to run the page and capture the output...though there may be some more elegant ways.

How to make sure you don't get WCF Faulted state exception?

This error can also be caused by having zero methods tagged with the OperationContract attribute. This was my problem when building a new service and testing it a long the way.

How do you force Visual Studio to regenerate the .designer files for aspx/ascx files?

I've encountered the same problem for years now, working in Visual Studio 2008. And I've tried every "solution" on StackOverflow and dozens of blogs, just like I'm sure all of you have. And sometimes they work, and sometimes they don't, just like I'm sure all of you have encountered. And apparently it's still an issue in VS2010 and VS2012.

So finally, a couple of months ago, I decided enough was enough, and over a few weeks I built a tool called "Redesigner" that generates .designer files. It's open-source under the BSD license, with the source code available on SourceForge — free to use, free to steal, free to do anything you please with. And it does what Visual Studio fails to do so often, which is generate .designer files quickly and reliably.

It's a stand-alone command-line tool that parses .aspx and .ascx files, performs all the necessary reflection magic, and spits out correct .designer files. It does all the parsing and reflection itself to avoid relying on existing code, which we all know too well is broken. It's written in C# against .NET 3.5, but it makes pains to avoid using even System.Web for anything other than type declarations, and it doesn't use or rely on Visual Studio at all.

Redesigner can generate new .designer files; and it offers a --verbose option so that when things go wrong, you get far better error messages than "Exception of type System.Exception was thrown." And there's a --verify option that can be used to tell you when your existing .designer files are broken — missing controls, bad property declarations, unreadable by Visual Studio, or otherwise just plain borked.

We've been using it at my workplace to get us out of jams for the better part of the last month now, and while Redesigner is still a beta, it's getting far enough along that it's worth sharing its existence with the public. I soon intend to create a Visual Studio plugin for it so you can simply right-click to verify or regenerate designer files the way you always wished you could. But in the interim, the command-line usage is pretty easy and will save you a lot of headaches.

Anyway, go download a copy of Redesigner now and stop pulling out your hair. You won't always need it, but when you do, you'll be glad you have it!

How to Find the Default Charset/Encoding in Java?



it seems to be the same encoding as the one used in your system's command line.

How to select option in drop down protractorjs e2e tests

The below example is the easiest way . I have tested and passed in Protractor Version 5.4.2

//Drop down selection  using option's visibility text 

 Or use this, it   $ isshort form for  .By.css

//To select using index

var select = element('userSelect'));
select.$('[value="1"]').click(); // To select using the index .$ means a shortcut to .By.css

Full code

describe('Protractor Demo App', function() {

  it('should have a title', function() {

    expect(browser.getTitle()).toEqual('Protractor practice website - Banking App');
    element(by.buttonText('Bank Manager Login')).click();
    element(by.buttonText('Open Account')).click();

    //Drop down selection  using option's visibility text 

    //This is a short form. $ in short form for  .By.css
    // element(by.model('currency')).$('[value="Dollar"]').click();

    //To select using index
    var select = element('userSelect'));
    select.$('[value="1"]').click(); // To select using the index .$ means a shortcut to .By.css
    browser.sleep(7500);// wait in miliseconds


Convenient C++ struct initialisation

Yet another way in C++ is

struct Point

 int x;
 int y;

    Point& setX(int xIn) { x = Xin; return *this;}
    Point& setY(int yIn) { y = Yin; return *this;}


Point pt;

ECONNREFUSED error when connecting to mongodb from node.js

I had same problem. It was resolved by running same code in Administrator Console.

Calling Member Functions within Main C++

declare it "static" like this:

static void MyClass::printInformation() { return; }

In Angular, how to redirect with $location.path as $ success callback

Here is the changeLocation example from this article

//be sure to inject $scope and $location
var changeLocation = function(url, forceReload) {
  $scope = $scope || angular.element(document).scope();
  if(forceReload || $scope.$$phase) {
    window.location = url;
  else {
    //only use this if you want to replace the history stack

    //this this if you want to change the URL and add it to the history stack

How can I detect if a selector returns null?

if ( $("#anid").length ) {
  alert("element(s) found")
else {
  alert("nothing found")

How to use lodash to find and return an object from Array?

You can do this easily in vanilla JS:

Using find

const savedViews = [{"description":"object1","id":1},{"description":"object2","id":2},{"description":"object3","id":3},{"description":"object4","id":4}];_x000D_
const view = 'object2';_x000D_
const delete_id = savedViews.find(obj => {_x000D_
  return obj.description === view;_x000D_

Using filter (original answer)

const savedViews = [{"description":"object1","id":1},{"description":"object2","id":2},{"description":"object3","id":3},{"description":"object4","id":4}];_x000D_
const view = 'object2';_x000D_
const delete_id = savedViews.filter(function (el) {_x000D_
  return el.description === view;_x000D_

How do you install Boost on MacOS?

If you are too lazy like me: conda install -c conda-forge boost

Git Pull While Ignoring Local Changes?

shortest way to do it is:

git pull --rebase --autostash

Python datetime - setting fixed hour and minute after using strptime to get day,month,year

Use datetime.replace:

from datetime import datetime
dt = datetime.strptime('26 Sep 2012', '%d %b %Y')
newdatetime = dt.replace(hour=11, minute=59)

How to iterate through SparseArray?

Ooor you just create your own ListIterator:

public final class SparseArrayIterator<E> implements ListIterator<E> {

private final SparseArray<E> array;
private int cursor;
private boolean cursorNowhere;

 * @param array
 *            to iterate over.
 * @return A ListIterator on the elements of the SparseArray. The elements
 *         are iterated in the same order as they occur in the SparseArray.
 *         {@link #nextIndex()} and {@link #previousIndex()} return a
 *         SparseArray key, not an index! To get the index, call
 *         {@link android.util.SparseArray#indexOfKey(int)}.
public static <E> ListIterator<E> iterate(SparseArray<E> array) {
    return iterateAt(array, -1);

 * @param array
 *            to iterate over.
 * @param key
 *            to start the iteration at. {@link android.util.SparseArray#indexOfKey(int)}
 *            < 0 results in the same call as {@link #iterate(android.util.SparseArray)}.
 * @return A ListIterator on the elements of the SparseArray. The elements
 *         are iterated in the same order as they occur in the SparseArray.
 *         {@link #nextIndex()} and {@link #previousIndex()} return a
 *         SparseArray key, not an index! To get the index, call
 *         {@link android.util.SparseArray#indexOfKey(int)}.
public static <E> ListIterator<E> iterateAtKey(SparseArray<E> array, int key) {
    return iterateAt(array, array.indexOfKey(key));

 * @param array
 *            to iterate over.
 * @param location
 *            to start the iteration at. Value < 0 results in the same call
 *            as {@link #iterate(android.util.SparseArray)}. Value >
 *            {@link android.util.SparseArray#size()} set to that size.
 * @return A ListIterator on the elements of the SparseArray. The elements
 *         are iterated in the same order as they occur in the SparseArray.
 *         {@link #nextIndex()} and {@link #previousIndex()} return a
 *         SparseArray key, not an index! To get the index, call
 *         {@link android.util.SparseArray#indexOfKey(int)}.
public static <E> ListIterator<E> iterateAt(SparseArray<E> array, int location) {
    return new SparseArrayIterator<E>(array, location);

private SparseArrayIterator(SparseArray<E> array, int location) {
    this.array = array;
    if (location < 0) {
        cursor = -1;
        cursorNowhere = true;
    } else if (location < array.size()) {
        cursor = location;
        cursorNowhere = false;
    } else {
        cursor = array.size() - 1;
        cursorNowhere = true;

public boolean hasNext() {
    return cursor < array.size() - 1;

public boolean hasPrevious() {
    return cursorNowhere && cursor >= 0 || cursor > 0;

public int nextIndex() {
    if (hasNext()) {
        return array.keyAt(cursor + 1);
    } else {
        throw new NoSuchElementException();

public int previousIndex() {
    if (hasPrevious()) {
        if (cursorNowhere) {
            return array.keyAt(cursor);
        } else {
            return array.keyAt(cursor - 1);
    } else {
        throw new NoSuchElementException();

public E next() {
    if (hasNext()) {
        if (cursorNowhere) {
            cursorNowhere = false;
        return array.valueAt(cursor);
    } else {
        throw new NoSuchElementException();

public E previous() {
    if (hasPrevious()) {
        if (cursorNowhere) {
            cursorNowhere = false;
        } else {
        return array.valueAt(cursor);
    } else {
        throw new NoSuchElementException();

public void add(E object) {
    throw new UnsupportedOperationException();

public void remove() {
    if (!cursorNowhere) {
        cursorNowhere = true;
    } else {
        throw new IllegalStateException();

public void set(E object) {
    if (!cursorNowhere) {
        array.setValueAt(cursor, object);
    } else {
        throw new IllegalStateException();

"Invalid form control" only in Google Chrome

this error get if add decimal format. i just add


switch() statement usage

In short, yes. But there are times when you might favor one vs. the other. Google "case switch vs. if else". There are some discussions already on SO too. Also, here is a good video that talks about it in the context of MATLAB:

Personally, when I have 3 or more cases, I usually just go with case/switch.

Format specifier %02x

You are actually getting the correct value out.

The way your x86 (compatible) processor stores data like this, is in Little Endian order, meaning that, the MSB is last in your output.

So, given your output:


the last two hex values 10 are the Most Significant Byte (2 hex digits = 1 byte = 8 bits (for (possibly unnecessary) clarification).

So, by reversing the memory storage order of the bytes, your value is actually: 01010101.

Hope that clears it up!

Unresolved reference issue in PyCharm

Although all the answers are really helpful, there's one tiny piece of information that should be explained explicitly:

  • Essentially, a project with multiple hierarchical directories work as a package with some attributes.
  • To import custom local created Classes, we need to navigate to the directory containing .py file and create an (empty) file there.

Why this helps is because this file is required to make Python treat the directory as containing packages. Cheers!

Calling a function on bootstrap modal open

You can use belw code for show and hide bootstrap model.

$('#my-model').on('', function (e) {
  // do something here...

and if you want to hide model then you can use below code.

$('#my-model').on('', function() {
    // do something here...

I hope this answer is useful for your project.

Could not open input file: composer.phar

If you go through the documentation, they have mentioned to use php composer.phar Link:

Don't use php composer.phar only give composer

Command: composer self-update

It will work.

How do I check in python if an element of a list is empty?

If you want to know if list element at index i is set or not, you can simply check the following:

if len(l)<=i:
    print ("empty")

If you are looking for something like what is a NULL-Pointer or a NULL-Reference in other languages, Python offers you None. That is you can write:

l[0] = None # here, list element at index 0 has to be set already
l.append(None) # here the list can be empty before
# checking
if l[i] == None:
    print ("list has actually an element at position i, which is None")

How to create a DataFrame from a text file in Spark

I know I am quite late to answer this but I have come up with a different answer:

val rdd = sc.textFile("/home/training/mydata/file.txt")

val text =",")).map(arrays=>(ararys(0),arrays(1))).toDF("id","name").show 

How do I convert a string to enum in TypeScript?

I was looking for an answer that can get an enum from a string, but in my case, the enums values had different string values counterpart. The OP had a simple enum for Color, but I had something different:

enum Gender {
  Male = 'Male',
  Female = 'Female',
  Other = 'Other',
  CantTell = "Can't tell"

When you try to resolve Gender.CantTell with a "Can't tell" string, it returns undefined with the original answer.

Another answer

Basically, I came up with another answer, strongly inspired by this answer:

export const stringToEnumValue = <ET, T>(enumObj: ET, str: string): T =>
  (enumObj as any)[Object.keys(enumObj).filter(k => (enumObj as any)[k] === str)[0]];


  • We take the first result of filter, assuming the client is passing a valid string from the enum. If it's not the case, undefined will be returned.
  • We cast enumObj to any, because with TypeScript 3.0+ (currently using TypeScript 3.5), the enumObj is resolved as unknown.

Example of Use

const cantTellStr = "Can't tell";

const cantTellEnumValue = stringToEnumValue<typeof Gender, Gender>(Gender, cantTellStr);
console.log(cantTellEnumValue); // Can't tell

Note: And, as someone pointed out in a comment, I also wanted to use the noImplicitAny.

Updated version

No cast to any and proper typings.

export const stringToEnumValue = <T, K extends keyof T>(enumObj: T, value: string): T[keyof T] | undefined =>
  enumObj[Object.keys(enumObj).filter((k) => enumObj[k as K].toString() === value)[0] as keyof typeof enumObj];

Also, the updated version has a easier way to call it and is more readable:

stringToEnumValue(Gender, "Can't tell");

Gradle's dependency cache may be corrupt (this sometimes occurs after a network connection timeout.)

For me, i was cloning a project from github which used a version of gradle higher than that which i had installed. I had two choices:

  1. Open gradle.wrapper-properties of a project you have that's building successfully, and copy the line that says distributionUrl=https\:// Use this to replace the same value in the project that's failing. That should do the trick.

  2. Your build might still fail if the gradle version used to build the project is higher than that which you just added. For this you should update the gradle version to the latest.

Python Requests library redirect new url

I think requests.head instead of requests.get will be more safe to call when handling url redirect,check the github issue here:

r = requests.head(url, allow_redirects=True)

How do I combine two lists into a dictionary in Python?

>>> dict(zip([1, 2, 3, 4], ['a', 'b', 'c', 'd']))
{1: 'a', 2: 'b', 3: 'c', 4: 'd'}

If they are not the same size, zip will truncate the longer one.

javax.xml.bind.JAXBException: Class *** nor any of its super class is known to this context

I had faced the similar error when supporting one application. It was about the generated classes for a SOAP Webservice.

The issue was caused due to the missing classes. When javax.xml.bind.Marshaller was trying to marshal the jaxb object it was not finding all dependent classes which were generated by using wsdl and xsd. after adding the jar with all the classes at the class path the issue was resolved.

How to set Spinner Default by its Value instead of Position?

Finally, i solved the problem by using following way, in which the position of the spinner can be get by its string

private int getPostiton(String locationid,Cursor cursor)
    int i;
    for(i=0;i< cursor.getCount()-1;i++)

        String locationVal = cursor.getString(cursor.getColumnIndex(RoadMoveDataBase.LT_LOCATION));  
            position = i+1;  
            position = 0;

Calling the method

    Spinner location2 = (Spinner)findViewById(;
    int location2id = getPostiton(cursor.getString(3),cursor);

I hope it will help for some one..

GET and POST methods with the same Action name in the same Controller

Can not multi action same name and same parameter

    public ActionResult Index()
        return View();
    public ActionResult Index(int id)
        return View();

althought int id is not used

iPhone app signing: A valid signing identity matching this profile could not be found in your keychain

What you need:

1) A private and a public key.

They have this symbol in your keychain:

alt text

2) A certificate made from the signing request of those keys

3) A provisioning profile linked to that certificate

Let's say you change computers and want to set up Xcode with provisioning profiles again. How do you do it?

  1. Open Xcode, press ctrl + O to open the Organizer, and delete all provisioning profiles you might have installed already.
  2. Open keychain access, and create a signing request which you save to file (when you create the request, a private and public key is created in your keychain).
  3. Create/Update a certificate in the provisioning portal by sending apple this signing request
  4. Download and install the newly created certificate.
  5. Revoke your provisioning profiles and update them with the new certificate.
  6. Download and install the newly updated provisioning profiles.

Tomcat 8 is not able to handle get request with '|' in query parameters?

The parameter tomcat.util.http.parser.HttpParser.requestTargetAllow is deprecated since Tomcat 8.5: tomcat official doc.

You can use relaxedQueryChars / relaxedPathChars in the connectors definition to allow these chars: tomcat official doc.

CORS - How do 'preflight' an httprequest?

During the preflight request, you should see the following two headers: Access-Control-Request-Method and Access-Control-Request-Headers. These request headers are asking the server for permissions to make the actual request. Your preflight response needs to acknowledge these headers in order for the actual request to work.

For example, suppose the browser makes a request with the following headers:

Access-Control-Request-Method: POST
Access-Control-Request-Headers: X-Custom-Header

Your server should then respond with the following headers:

Access-Control-Allow-Methods: GET, POST
Access-Control-Allow-Headers: X-Custom-Header

Pay special attention to the Access-Control-Allow-Headers response header. The value of this header should be the same headers in the Access-Control-Request-Headers request header, and it can not be '*'.

Once you send this response to the preflight request, the browser will make the actual request. You can learn more about CORS here:

Accessing Redux state in an action creator?

Presenting an alternative way of solving this. This may be better or worse than Dan's solution, depending on your application.

You can get the state from the reducers into the actions by splitting the action in 2 separate functions: first ask for the data, second act on the data. You can do that by using redux-loop.

First 'kindly ask for the data'

export const SOME_ACTION = 'SOME_ACTION';
export function someAction() {
    return {
        type: SOME_ACTION,

In the reducer, intercept the ask and provide the data to the second stage action by using redux-loop.

import { loop, Cmd } from 'redux-loop';
const initialState = { data: '' }
export default (state=initialState, action) => {
    switch(action.type) {
        case SOME_ACTION: {
            return loop(state, Cmd.action(anotherAction(

With the data in hand, do whatever you initially wanted

export function anotherAction(data) {
    return {
        type: ANOTHER_ACTION,
        payload: data,

Hope this helps someone.

Synchronous XMLHttpRequest warning and <script>

if you just need to load script dont do as bellow

$(document.body).html('<script type="text/javascript" src="/json.js" async="async"><\/script>');

Try this

var scriptEl = document.createElement('SCRIPT');
    scriptEl.src = "/module/script/form?_t="+(new Date()).getTime();
    //$('#holder').append(scriptEl) // <--- create warning

How to make a variadic macro (variable number of arguments)

#define DEBUG

#ifdef DEBUG
  #define PRINT print
  #define PRINT(...) ((void)0) //strip out PRINT instructions from code

void print(const char *fmt, ...) {

    va_list args;
    va_start(args, fmt);
    vsprintf(str, fmt, args);

        printf("%s\n", str);


int main() {
   PRINT("[%s %d, %d] Hello World", "March", 26, 2009);
   return 0;

If the compiler does not understand variadic macros, you can also strip out PRINT with either of the following:

#define PRINT //


#define PRINT if(0)print

The first comments out the PRINT instructions, the second prevents PRINT instruction because of a NULL if condition. If optimization is set, the compiler should strip out never executed instructions like: if(0) print("hello world"); or ((void)0);

How to push to History in React Router v4?

so the way I do it is: - instead of redirecting using history.push, I just use Redirect component from react-router-dom When using this component you can just pass push=true, and it will take care of the rest

import * as React from 'react';
import { Redirect } from 'react-router-dom';
class Example extends React.Component {
  componentDidMount() {
      redirectTo: '/test/path'

  render() {
    const { redirectTo } = this.state;

    return <Redirect to={{pathname: redirectTo}} push={true}/>

Programmatically obtain the phone number of the Android phone

Wouldn't be recommending to use TelephonyManager as it requires the app to require READ_PHONE_STATE permission during runtime.

<uses-permission android:name="android.permission.READ_PHONE_STATE"/> 

Should be using Google's Play Service for Authentication, and it will able to allow User to select which phoneNumber to use, and handles multiple SIM cards, rather than us trying to guess which one is the primary SIM Card.

implementation "$play_service_auth_version"
fun main() {
    val googleApiClient = GoogleApiClient.Builder(context)

    val hintRequest = HintRequest.Builder()

    val hintPickerIntent = Auth.CredentialsApi.getHintPickerIntent(
        googleApiClient, hintRequest

        hintPickerIntent.intentSender, REQUEST_PHONE_NUMBER, null, 0, 0, 0

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    when (requestCode) {
            if (requestCode == Activity.RESULT_OK) {
                val credential = data?.getParcelableExtra<Credential>(Credential.EXTRA_KEY)
                val selectedPhoneNumber = credential?.id

How to set the height and the width of a textfield in Java?

You should not play with the height. Let the text field determine the height based on the font used.

If you want to control the width of the text field then you can use


to let the text field determine the preferred width.

Or if you want the width to be the entire width of the parent panel then you need to use an appropriate layout. Maybe the NORTH of a BorderLayout.

See the Swing tutorial on Layout Managers for more information.

Git: How to reset a remote Git repository to remove all commits?

Completely reset?

  1. Delete the .git directory locally.

  2. Recreate the git repostory:

    $ cd (project-directory)
    $ git init
    $ (add some files)
    $ git add .
    $ git commit -m 'Initial commit'
  3. Push to remote server, overwriting. Remember you're going to mess everyone else up doing this … you better be the only client.

    $ git remote add origin <url>
    $ git push --force --set-upstream origin master

how to extract only the year from the date in sql server 2008?

SQL Server Script

declare @iDate datetime
set @iDate=GETDATE()

print year(@iDate) -- for Year

print month(@iDate) -- for Month

print day(@iDate) -- for Day

Java: Multiple class declarations in one file

No. You can't. But it is very possible in Scala:

class Foo {val bar = "a"}
class Bar {val foo = "b"}

How to reference static assets within vue javascript

this finally worked for me, image passed as prop:

<img :src="require(`../../assets/${image}.svg`)">

Can you issue pull requests from the command line on GitHub?

I'm using simple alias to create pull request,

alias pr='open -n -a "Google Chrome" --args "$(git_current_branch)\?expand\=1"'

How to close a GUI when I push a JButton?

See JFrame.setDefaultCloseOperation(DISPOSE_ON_CLOSE)1. You might also use EXIT_ON_CLOSE, but it is better to explicitly clean up any running threads, then when the last GUI element becomes invisible, the EDT & JRE will end.

The 'button' to invoke this operation is already on a frame.

  1. See this answer to How to best position Swing GUIs? for a demo. of the DISPOSE_ON_CLOSE functionality.

    The JRE will end after all 3 frames are closed by clicking the X button.

Difference between an API and SDK

You use an SDK to access functionality of a library, and an API to control it.

How do I record audio on iPhone with AVAudioRecorder?

This is from Multimedia programming guide...

- (IBAction) recordOrStop: (id) sender {
if (recording) {
    [soundRecorder stop];
    recording = NO;
    self.soundRecorder = nil;
    [recordOrStopButton setTitle: @"Record" forState:
    [recordOrStopButton setTitle: @"Record" forState:
    [[AVAudioSession sharedInstance] setActive: NO error:nil];
else {
    [[AVAudioSession sharedInstance]
     setCategory: AVAudioSessionCategoryRecord
     error: nil];
    NSDictionary *recordSettings =
    [[NSDictionary alloc] initWithObjectsAndKeys:[NSNumber numberWithFloat: 44100.0], AVSampleRateKey,
     [NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey,
     [NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
     [NSNumber numberWithInt: AVAudioQualityMax],
    AVAudioRecorder *newRecorder =
    [[AVAudioRecorder alloc] initWithURL: soundFileURL
                                settings: recordSettings
                                   error: nil];
    [recordSettings release];
    self.soundRecorder = newRecorder;
    [newRecorder release];
    soundRecorder.delegate = self;
    [soundRecorder prepareToRecord];
    [soundRecorder record];
    [recordOrStopButton setTitle: @"Stop" forState: UIControlStateNormal];
    [recordOrStopButton setTitle: @"Stop" forState: UIControlStateHighlighted];
    recording = YES;

Get random sample from list while maintaining ordering of items?

Simple-to-code O(N + K*log(K)) way

Take a random sample without replacement of the indices, sort the indices, and take them from the original.

indices = random.sample(range(len(myList)), K)
[myList[i] for i in sorted(indices)]

Or more concisely:

[x[1] for x in sorted(random.sample(enumerate(myList),K))]

Optimized O(N)-time, O(1)-auxiliary-space way

You can alternatively use a math trick and iteratively go through myList from left to right, picking numbers with dynamically-changing probability (N-numbersPicked)/(total-numbersVisited). The advantage of this approach is that it's an O(N) algorithm since it doesn't involve sorting!

from __future__ import division

def orderedSampleWithoutReplacement(seq, k):
    if not 0<=k<=len(seq):
        raise ValueError('Required that 0 <= sample_size <= population_size')

    numbersPicked = 0
    for i,number in enumerate(seq):
        prob = (k-numbersPicked)/(len(seq)-i)
        if random.random() < prob:
            yield number
            numbersPicked += 1

Proof of concept and test that probabilities are correct:

Simulated with 1 trillion pseudorandom samples over the course of 5 hours:

>>> Counter(
        tuple(orderedSampleWithoutReplacement([0,1,2,3], 2))
        for _ in range(10**9)
    (0, 3): 166680161, 
    (1, 2): 166672608, 
    (0, 2): 166669915, 
    (2, 3): 166667390, 
    (1, 3): 166660630, 
    (0, 1): 166649296

Probabilities diverge from true probabilities by less a factor of 1.0001. Running this test again resulted in a different order meaning it isn't biased towards one ordering. Running the test with fewer samples for [0,1,2,3,4], k=3 and [0,1,2,3,4,5], k=4 had similar results.

edit: Not sure why people are voting up wrong comments or afraid to upvote... NO, there is nothing wrong with this method. =)

(Also a useful note from user tegan in the comments: If this is python2, you will want to use xrange, as usual, if you really care about extra space.)

edit: Proof: Considering the uniform distribution (without replacement) of picking a subset of k out of a population seq of size len(seq), we can consider a partition at an arbitrary point i into 'left' (0,1,...,i-1) and 'right' (i,i+1,...,len(seq)). Given that we picked numbersPicked from the left known subset, the remaining must come from the same uniform distribution on the right unknown subset, though the parameters are now different. In particular, the probability that seq[i] contains a chosen element is #remainingToChoose/#remainingToChooseFrom, or (k-numbersPicked)/(len(seq)-i), so we simulate that and recurse on the result. (This must terminate since if #remainingToChoose == #remainingToChooseFrom, then all remaining probabilities are 1.) This is similar to a probability tree that happens to be dynamically generated. Basically you can simulate a uniform probability distribution by conditioning on prior choices (as you grow the probability tree, you pick the probability of the current branch such that it is aposteriori the same as prior leaves, i.e. conditioned on prior choices; this will work because this probability is uniformly exactly N/k).

edit: Timothy Shields mentions Reservoir Sampling, which is the generalization of this method when len(seq) is unknown (such as with a generator expression). Specifically the one noted as "algorithm R" is O(N) and O(1) space if done in-place; it involves taking the first N element and slowly replacing them (a hint at an inductive proof is also given). There are also useful distributed variants and miscellaneous variants of reservoir sampling to be found on the wikipedia page.

edit: Here's another way to code it below in a more semantically obvious manner.

from __future__ import division
import random

def orderedSampleWithoutReplacement(seq, sampleSize):
    totalElems = len(seq)
    if not 0<=sampleSize<=totalElems:
        raise ValueError('Required that 0 <= sample_size <= population_size')

    picksRemaining = sampleSize
    for elemsSeen,element in enumerate(seq):
        elemsRemaining = totalElems - elemsSeen
        prob = picksRemaining/elemsRemaining
        if random.random() < prob:
            yield element
            picksRemaining -= 1

from collections import Counter         
    tuple(orderedSampleWithoutReplacement([0,1,2,3], 2))
    for _ in range(10**5)


How to create the branch from specific commit in different branch

You have to do:

git branch <branch_name> <commit>

(you were interchanging the branch name and commit)

Or you can do:

git checkout -b <branch_name> <commit>

If in place of you use branch name, you get a branch out of tip of the branch.

Find an object in array?

Swift 3

if yourArray.contains(item) {
   //item found, do what you want
   //item not found 

How to get < span > value?

<div id="test">
<div id="test2"></div>

<script type="text/javascript">
    var getDiv = document.getElementById('test');
    var getSpan = getDiv.getElementsByTagName('span');???
    var divDump = document.getElementById('test2');

    for (var i=0; i<getSpan.length; i++) {
        divDump.innerHTML = divDump.innerHTML + ' ' + getSpan[i].innerHTML;


nuget 'packages' element is not declared warning

You will see it only when the file is open. When you'll close the file in Visual Studio the warnings goes away

Remove numbers from string sql server

Try below for your query. where val is your string or column name.

CASE WHEN PATINDEX('%[a-z]%', REVERSE(val)) > 1
                THEN LEFT(val, LEN(val) - PATINDEX('%[a-z]%', REVERSE(val)) + 1)
            ELSE '' END

No module named MySQLdb

pip install --user mysqlclient 

above works for me like charm for me.I go the error from sqlalchemy actually. Environment information :

Python : 3.6, Ubuntu : 16.04,conda 4.6.8

How does strcmp() work?

This, from the masters themselves (K&R, 2nd ed., pg. 106):

// strcmp: return < 0 if s < t, 0 if s == t, > 0 if s > t
int strcmp(char *s, char *t) 
    int i;

    for (i = 0; s[i] == t[i]; i++)
        if (s[i] == '\0')
            return 0;
    return s[i] - t[i];

Can RDP clients launch remote applications and not desktops

Another way is shown in this CodeProject article:

The basic idea is to create a virutal channel that sends the windows position of the app(s) you want to show, then only render that part of the window on the client.

IIS Request Timeout on long ASP.NET operation

If you want to extend the amount of time permitted for an ASP.NET script to execute then increase the Server.ScriptTimeout value. The default is 90 seconds for .NET 1.x and 110 seconds for .NET 2.0 and later.

For example:

// Increase script timeout for current page to five minutes
Server.ScriptTimeout = 300;

This value can also be configured in your web.config file in the httpRuntime configuration element:

<!-- Increase script timeout to five minutes -->
<httpRuntime executionTimeout="300" 
  ... other configuration attributes ...

enter image description here

Please note according to the MSDN documentation:

"This time-out applies only if the debug attribute in the compilation element is False. Therefore, if the debug attribute is True, you do not have to set this attribute to a large value in order to avoid application shutdown while you are debugging."

If you've already done this but are finding that your session is expiring then increase the ASP.NET HttpSessionState.Timeout value:

For example:

// Increase session timeout to thirty minutes
Session.Timeout = 30;

This value can also be configured in your web.config file in the sessionState configuration element:

      timeout="30" />

If your script is taking several minutes to execute and there are many concurrent users then consider changing the page to an Asynchronous Page. This will increase the scalability of your application.

The other alternative, if you have administrator access to the server, is to consider this long running operation as a candidate for implementing as a scheduled task or a windows service.

Convert list or numpy array of single element to float in python

I would simply use,

np.asarray(input, dtype=np.float)[0]
  • If input is an ndarray of the right dtype, there is no overhead, since np.asarray does nothing in this case.
  • if input is a list, np.asarray makes sure the output is of the right type.

How can I check if an argument is defined when starting/calling a batch file?

IF "%1"=="" will fail, all versions of this will fail under certain poison character conditions. Only IF DEFINED or IF NOT DEFINED are safe

How to check null objects in jQuery

Check the jQuery FAQ...

You can use the length property of the jQuery collection returned by your selector:

if ( $('#myDiv').length ){}

PHP: How do you determine every Nth iteration of a loop?

You can also do it without modulus. Just reset your counter when it matches.

if($counter == 2) { // matches every 3 iterations
   echo 'image-file';
   $counter = 0; 

How to locate the php.ini file (xampp)

step1 :open xampp control panel

step 2: then click apache module config button.

step 3. after that you able to see some config file list.

step 4: then click the php.ini will be open into default editor.

image was given blow for refernce. enter image description here

Update a local branch with the changes from a tracked remote branch

You have set the upstream of that branch


git branch -f --track my_local_branch origin/my_remote_branch
# OR (if my_local_branch is currently checked out):
$ git branch --set-upstream-to my_local_branch origin/my_remote_branch

(git branch -f --track won't work if the branch is checked out: use the second command git branch --set-upstream-to instead, or you would get "fatal: Cannot force update the current branch.")

That means your branch is already configured with:

branch.my_local_branch.remote origin
branch.my_local_branch.merge my_remote_branch

Git already has all the necessary information.
In that case:

# if you weren't already on my_local_branch branch:
git checkout my_local_branch 
# then:
git pull

is enough.

If you hadn't establish that upstream branch relationship when it came to push your 'my_local_branch', then a simple git push -u origin my_local_branch:my_remote_branch would have been enough to push and set the upstream branch.
After that, for the subsequent pulls/pushes, git pull or git push would, again, have been enough.

How to get .pem file from .key and .crt files?

this is the best option to create .pem file

openssl pkcs12 -in MyPushApp.p12 -out MyPushApp.pem -nodes -clcerts

Rotate camera in Three.js with mouse

OrbitControls and TrackballControls seems to be good for this purpose.

controls = new THREE.TrackballControls( camera );
controls.rotateSpeed = 1.0;
controls.zoomSpeed = 1.2;
controls.panSpeed = 0.8;
controls.noZoom = false;
controls.noPan = false;
controls.staticMoving = true;
controls.dynamicDampingFactor = 0.3;

update in render


Azure SQL Database "DTU percentage" metric

To check the accurate usage for your services be it is free (as per always free or 12 months free) or Pay-As-You-Go, it is important to monitor the usage so that you know upfront on the cost incurred or when to upgrade your service tier.

To check your free service usage and its limits, Go to search in Portal, search with "Subscription" and click on it. you will see the details of each service that you have used.

In case of free azure from Microsoft, you get to see the cost incurred for each one.

Visit Check usage of free services included with your Azure free account enter image description here

Hope this helps someone!

Compile to stand alone exe for C# app in Visual Studio 2010

Are you sure you selected Console Application? I'm running VS 2010 and with the vanilla settings a C# console app builds to \bin\debug. Try to create a new Console Application project, with the language set to C#. Build the project, and go to Project/[Console Application 1]Properties. In the Build tab, what is the Output path? It should default to bin\debug, unless you have some restricted settings on your workstation,etc. Also review the build output window and see if any errors are being thrown - in which case nothing will be built to the output folder, of course...

Get a json via Http Request in NodeJS

Just tell request that you are using json:true and forget about header and parse

var options = {
    hostname: '',
    port: app.get('port'),
    path: '/users',
    method: 'GET',
request(options, function(error, response, body){
    if(error) console.log(error);
    else console.log(body);

and the same for post

var options = {
    hostname: '',
    port: app.get('port'),
    path: '/users',
    method: 'POST',
    json: {"name":"John", "lastname":"Doe"}
request(options, function(error, response, body){
    if(error) console.log(error);
    else console.log(body);

Set color of TextView span in Android

Some answers here aren't up to date. Because, you will (in most of cases) add a custom clic action on your link.

Besides, as provided by the documentation help, your spanned string link color will have a default one. "The default link color is the theme's accent color or android:textColorLink if this attribute is defined in the theme".

Here is the way to do it safely.

 private class CustomClickableSpan extends ClickableSpan {

    private int color = -1;

    public CustomClickableSpan(){
        if(getContext() != null) {
            color = ContextCompat.getColor(getContext(), R.color.colorPrimaryDark);

    public void updateDrawState(@NonNull TextPaint ds) {
        ds.setColor(color != -1 ? color : ds.linkColor);

    public void onClick(@NonNull View widget) {

Then to use it.

   String text = "my text with action";
    hideText= new SpannableString(text);
    hideText.setSpan(new CustomClickableSpan(){

        public void onClick(@NonNull View widget) {
            // your action here !

    }, 0, text.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    // don't forget this ! or this will not work !

Hope this will strongly help !

Switch/toggle div (jQuery)

function toggling_fields_contact_bank(class_name) {
    jQuery("." + class_name).animate({
        height: 'toggle'

A monad is just a monoid in the category of endofunctors, what's the problem?

I came to this post by way of better understanding the inference of the infamous quote from Mac Lane's Category Theory For the Working Mathematician.

In describing what something is, it's often equally useful to describe what it's not.

The fact that Mac Lane uses the description to describe a Monad, one might imply that it describes something unique to monads. Bear with me. To develop a broader understanding of the statement, I believe it needs to be made clear that he is not describing something that is unique to monads; the statement equally describes Applicative and Arrows among others. For the same reason we can have two monoids on Int (Sum and Product), we can have several monoids on X in the category of endofunctors. But there is even more to the similarities.

Both Monad and Applicative meet the criteria:

  • endo => any arrow, or morphism that starts and ends in the same place
  • functor => any arrow, or morphism between two Categories

    (e.g., in day to day Tree a -> List b, but in Category Tree -> List)

  • monoid => single object; i.e., a single type, but in this context, only in regards to the external layer; so, we can't have Tree -> List, only List -> List.

The statement uses "Category of..." This defines the scope of the statement. As an example, the Functor Category describes the scope of f * -> g *, i.e., Any functor -> Any functor, e.g., Tree * -> List * or Tree * -> Tree *.

What a Categorical statement does not specify describes where anything and everything is permitted.

In this case, inside the functors, * -> * aka a -> b is not specified which means Anything -> Anything including Anything else. As my imagination jumps to Int -> String, it also includes Integer -> Maybe Int, or even Maybe Double -> Either String Int where a :: Maybe Double; b :: Either String Int.

So the statement comes together as follows:

  • functor scope :: f a -> g b (i.e., any parameterized type to any parameterized type)
  • endo + functor :: f a -> f b (i.e., any one parameterized type to the same parameterized type) ... said differently,
  • a monoid in the category of endofunctor

So, where is the power of this construct? To appreciate the full dynamics, I needed to see that the typical drawings of a monoid (single object with what looks like an identity arrow, :: single object -> single object), fails to illustrate that I'm permitted to use an arrow parameterized with any number of monoid values, from the one type object permitted in Monoid. The endo, ~ identity arrow definition of equivalence ignores the functor's type value and both the type and value of the most inner, "payload" layer. Thus, equivalence returns true in any situation where the functorial types match (e.g., Nothing -> Just * -> Nothing is equivalent to Just * -> Just * -> Just * because they are both Maybe -> Maybe -> Maybe).

Sidebar: ~ outside is conceptual, but is the left most symbol in f a. It also describes what "Haskell" reads-in first (big picture); so Type is "outside" in relation to a Type Value. The relationship between layers (a chain of references) in programming is not easy to relate in Category. The Category of Set is used to describe Types (Int, Strings, Maybe Int etc.) which includes the Category of Functor (parameterized Types). The reference chain: Functor Type, Functor values (elements of that Functor's set, e.g., Nothing, Just), and in turn, everything else each functor value points to. In Category the relationship is described differently, e.g., return :: a -> m a is considered a natural transformation from one Functor to another Functor, different from anything mentioned thus far.

Back to the main thread, all in all, for any defined tensor product and a neutral value, the statement ends up describing an amazingly powerful computational construct born from its paradoxical structure:

  • on the outside it appears as a single object (e.g., :: List); static
  • but inside, permits a lot of dynamics
    • any number of values of the same type (e.g., Empty | ~NonEmpty) as fodder to functions of any arity. The tensor product will reduce any number of inputs to a single value... for the external layer (~fold that says nothing about the payload)
    • infinite range of both the type and values for the inner most layer

In Haskell, clarifying the applicability of the statement is important. The power and versatility of this construct, has absolutely nothing to do with a monad per se. In other words, the construct does not rely on what makes a monad unique.

When trying to figure out whether to build code with a shared context to support computations that depend on each other, versus computations that can be run in parallel, this infamous statement, with as much as it describes, is not a contrast between the choice of Applicative, Arrows and Monads, but rather is a description of how much they are the same. For the decision at hand, the statement is moot.

This is often misunderstood. The statement goes on to describe join :: m (m a) -> m a as the tensor product for the monoidal endofunctor. However, it does not articulate how, in the context of this statement, (<*>) could also have also been chosen. It truly is a an example of six/half dozen. The logic for combining values are exactly alike; same input generates the same output from each (unlike the Sum and Product monoids for Int because they generate different results when combining Ints).

So, to recap: A monoid in the category of endofunctors describes:

   ~t :: m * -> m * -> m *
   and a neutral value for m *

(<*>) and (>>=) both provide simultaneous access to the two m values in order to compute the the single return value. The logic used to compute the return value is exactly the same. If it were not for the different shapes of the functions they parameterize (f :: a -> b versus k :: a -> m b) and the position of the parameter with the same return type of the computation (i.e., a -> b -> b versus b -> a -> b for each respectively), I suspect we could have parameterized the monoidal logic, the tensor product, for reuse in both definitions. As an exercise to make the point, try and implement ~t, and you end up with (<*>) and (>>=) depending on how you decide to define it forall a b.

If my last point is at minimum conceptually true, it then explains the precise, and only computational difference between Applicative and Monad: the functions they parameterize. In other words, the difference is external to the implementation of these type classes.

In conclusion, in my own experience, Mac Lane's infamous quote provided a great "goto" meme, a guidepost for me to reference while navigating my way through Category to better understand the idioms used in Haskell. It succeeds at capturing the scope of a powerful computing capacity made wonderfully accessible in Haskell.

However, there is irony in how I first misunderstood the statement's applicability outside of the monad, and what I hope conveyed here. Everything that it describes turns out to be what is similar between Applicative and Monads (and Arrows among others). What it doesn't say is precisely the small but useful distinction between them.

- E

How to retrieve a single file from a specific revision in Git?

Using git show

To complete your own answer, the syntax is indeed

git show object
git show $REV:$FILE
git show somebranch:from/the/root/myfile.txt
git show HEAD^^^:test/

The command takes the usual style of revision, meaning you can use any of the following:

  1. branch name (as suggested by ash)
  2. HEAD + x number of ^ characters
  3. The SHA1 hash of a given revision
  4. The first few (maybe 5) characters of a given SHA1 hash

Tip It's important to remember that when using "git show", always specify a path from the root of the repository, not your current directory position.

(Although Mike Morearty mentions that, at least with git, you can specify a relative path by putting "./" at the beginning of the path. For example:

git show HEAD^^:./


Using git restore

With Git 2.23+ (August 2019), you can also use git restore which replaces the confusing git checkout command

git restore -s <SHA1>     -- afile
git restore -s somebranch -- afile

That would restore on the working tree only the file as present in the "source" (-s) commit SHA1 or branch somebranch.
To restore also the index:

git restore -s <SHA1> -SW -- afile

(-SW: short for --staged --worktree)

Using low-level git plumbing commands

Before git1.5.x, this was done with some plumbing:

git ls-tree <rev>
show a list of one or more 'blob' objects within a commit

git cat-file blob <file-SHA1>
cat a file as it has been committed within a specific revision (similar to svn cat). use git ls-tree to retrieve the value of a given file-sha1

git cat-file -p $(git-ls-tree $REV $file | cut -d " " -f 3 | cut -f 1)::

git-ls-tree lists the object ID for $file in revision $REV, this is cut out of the output and used as an argument to git-cat-file, which should really be called git-cat-object, and simply dumps that object to stdout.

Note: since Git 2.11 (Q4 2016), you can apply a content filter to the git cat-file output.

See commit 3214594, commit 7bcf341 (09 Sep 2016), commit 7bcf341 (09 Sep 2016), and commit b9e62f6, commit 16dcc29 (24 Aug 2016) by Johannes Schindelin (dscho).
(Merged by Junio C Hamano -- gitster -- in commit 7889ed2, 21 Sep 2016)

git config diff.txt.textconv "tr A-Za-z N-ZA-Mn-za-m <"
git cat-file --textconv --batch

Note: "git cat-file --textconv" started segfaulting recently (2017), which has been corrected in Git 2.15 (Q4 2017)

See commit cc0ea7c (21 Sep 2017) by Jeff King (peff).
(Merged by Junio C Hamano -- gitster -- in commit bfbc2fc, 28 Sep 2017)

How can I check MySQL engine type for a specific table?

If you're using MySQL Workbench, right-click a table and select alter table.

In that window you can see your table Engine and also change it.

Failed binder transaction when putting an bitmap dynamically in a widget

I have solved this issue by storing images on internal storage and then using .setImageURI() rather than .setBitmap().

ICommand MVVM implementation

@Carlo I really like your implementation of this, but I wanted to share my version and how to use it in my ViewModel

First implement ICommand

public class Command : ICommand
    public delegate void ICommandOnExecute();
    public delegate bool ICommandOnCanExecute();

    private ICommandOnExecute _execute;
    private ICommandOnCanExecute _canExecute;

    public Command(ICommandOnExecute onExecuteMethod, ICommandOnCanExecute onCanExecuteMethod = null)
        _execute = onExecuteMethod;
        _canExecute = onCanExecuteMethod;

    #region ICommand Members

    public event EventHandler CanExecuteChanged
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }

    public bool CanExecute(object parameter)
        return _canExecute?.Invoke() ?? true;

    public void Execute(object parameter)


Notice I have removed the parameter from ICommandOnExecute and ICommandOnCanExecute and added a null to the constructor

Then to use in the ViewModel

public Command CommandToRun_WithCheck
        return new Command(() =>
            // Code to run
        }, () =>
            // Code to check to see if we can run 
            // Return true or false

public Command CommandToRun_NoCheck
        return new Command(() =>
            // Code to run

I just find this way cleaner as I don't need to assign variables and then instantiate, it all done in one go.

complex if statement in python

This should do it:

elif var == 80 or var == 443 or 1024 <= var <= 65535:

Set div height equal to screen size

Using CSS {height: 100%;} matches the height of the parent. This could be anything, meaning smaller or bigger than the screen. Using {height: 100vh;} matches the height of the viewport.

.container {
    height: 100vh;
    overflow: auto;

According to Mozilla's official documents, 1vh is:

Equal to 1% of the height of the viewport's initial containing block.

Byte Array and Int conversion in Java

That's a lot of work for:

public static int byteArrayToLeInt(byte[] b) {
    final ByteBuffer bb = ByteBuffer.wrap(b);
    return bb.getInt();

public static byte[] leIntToByteArray(int i) {
    final ByteBuffer bb = ByteBuffer.allocate(Integer.SIZE / Byte.SIZE);
    return bb.array();

This method uses the Java ByteBuffer and ByteOrder functionality in the java.nio package. This code should be preferred where readability is required. It should also be very easy to remember.

I've shown Little Endian byte order here. To create a Big Endian version you can simply leave out the call to order(ByteOrder).

In code where performance is higher priority than readability (about 10x as fast):

public static int byteArrayToLeInt(byte[] encodedValue) {
    int value = (encodedValue[3] << (Byte.SIZE * 3));
    value |= (encodedValue[2] & 0xFF) << (Byte.SIZE * 2);
    value |= (encodedValue[1] & 0xFF) << (Byte.SIZE * 1);
    value |= (encodedValue[0] & 0xFF);
    return value;

public static byte[] leIntToByteArray(int value) {
    byte[] encodedValue = new byte[Integer.SIZE / Byte.SIZE];
    encodedValue[3] = (byte) (value >> Byte.SIZE * 3);
    encodedValue[2] = (byte) (value >> Byte.SIZE * 2);   
    encodedValue[1] = (byte) (value >> Byte.SIZE);   
    encodedValue[0] = (byte) value;
    return encodedValue;

Just reverse the byte array index to count from zero to three to create a Big Endian version of this code.


  • In Java 8 you can also make use of the Integer.BYTES constant, which is more succinct than Integer.SIZE / Byte.SIZE.

Export html table data to Excel using JavaScript / JQuery is not working properly in chrome browser

You can use tableToExcel.js to export table in excel file.

This works in a following way :

1). Include this CDN in your project/file

<script src="[email protected]/dist/tableToExcel.js"></script>

2). Either Using JavaScript:

<button id="btnExport" onclick="exportReportToExcel(this)">EXPORT REPORT</button>

function exportReportToExcel() {
  let table = document.getElementsByTagName("table"); // you can use document.getElementById('tableId') as well by providing id to the table tag
  TableToExcel.convert(table[0], { // html code may contain multiple tables so here we are refering to 1st table tag
    name: `export.xlsx`, // fileName you could use any name
    sheet: {
      name: 'Sheet 1' // sheetName

3). Or by Using Jquery

<button id="btnExport">EXPORT REPORT</button>

    $("#btnExport").click(function() {
        let table = document.getElementsByTagName("table");
        TableToExcel.convert(table[0], { // html code may contain multiple tables so here we are refering to 1st table tag
           name: `export.xlsx`, // fileName you could use any name
           sheet: {
              name: 'Sheet 1' // sheetName

You may refer to this github link for any other information

or for referring the live example visit the following link

Hope this will help someone :-)


In my case TOP LEVEL EXCEPTION was throw because of a special char in project path. Just closed the project, changed "á" to "a" and reopened the project. Works!

Merging dataframes on index with pandas

You should be able to use join, which joins on the index as default. Given your desired result, you must use outer as the join type.

>>> df1.join(df2, how='outer')
            V1  V2
A 1/1/2012  12  15
  2/1/2012  14 NaN
  3/1/2012 NaN  21
B 1/1/2012  15  24
  2/1/2012   8   9
C 1/1/2012  17 NaN
  2/1/2012   9 NaN
D 1/1/2012 NaN   7
  2/1/2012 NaN  16

Signature: _.join(other, on=None, how='left', lsuffix='', rsuffix='', sort=False) Docstring: Join columns with other DataFrame either on index or on a key column. Efficiently Join multiple DataFrame objects by index at once by passing a list.

Always show vertical scrollbar in <select>


overflow-y: scroll

in your css bud.

How to call code behind server method from a client side JavaScript function?

Yes, you can make a web method like..

public static String SetName(string name)
    return "Your String"

And then call it in JavaScript like,

PageMethods.SetName(parameterValueIfAny, onSuccessMethod,onFailMethod);

This is also required :

<asp:ScriptManager ID="ScriptMgr" runat="server" EnablePageMethods="true"></asp:ScriptManager>

How to get current url in view in core 1.0

You need scheme, host, path and queryString

@string.Format("{0}://{1}{2}{3}", Context.Request.Scheme, Context.Request.Host, Context.Request.Path, Context.Request.QueryString)

or using new C#6 feature "String interpolation"


HTTP Status 405 - Method Not Allowed Error for Rest API

In above code variable "ver" is assign to null, print "ver" before returning and see the value. As this "ver" having null service is send status as "204 No Content".

And about status code "405 - Method Not Allowed" will get this status code when rest controller or service only supporting GET method but from client side your trying with POST with valid uri request, during such scenario get status as "405 - Method Not Allowed"

Python List vs. Array - when to use?

This answer will sum up almost all the queries about when to use List and Array:

  1. The main difference between these two data types is the operations you can perform on them. For example, you can divide an array by 3 and it will divide each element of array by 3. Same can not be done with the list.

  2. The list is the part of python's syntax so it doesn't need to be declared whereas you have to declare the array before using it.

  3. You can store values of different data-types in a list (heterogeneous), whereas in Array you can only store values of only the same data-type (homogeneous).

  4. Arrays being rich in functionalities and fast, it is widely used for arithmetic operations and for storing a large amount of data - compared to list.

  5. Arrays take less memory compared to lists.

Java regular expression OR operator

You can just use the pipe on its own:


for example:

String s = "string1, string2, string3";
System.out.println(s.replaceAll("string1|string2", "blah"));


blah, blah, string3

The main reason to use parentheses is to limit the scope of the alternatives:

String s = "string1, string2, string3";
System.out.println(s.replaceAll("string(1|2)", "blah"));

has the same output. but if you just do this:

String s = "string1, string2, string3";
System.out.println(s.replaceAll("string1|2", "blah"));

you get:

blah, stringblah, string3

because you've said "string1" or "2".

If you don't want to capture that part of the expression use ?::

String s = "string1, string2, string3";
System.out.println(s.replaceAll("string(?:1|2)", "blah"));

Filter Extensions in HTML form upload

The accept attribute specifies a comma-separated list of content types (MIME types) that the target of the form will process correctly. Unfortunately this attribute is ignored by all the major browsers, so it does not affect the browser's file dialog in any way.

How to count how many values per level in a given factor?

Use the package plyr with lapply to get frequencies for every value (level) and every variable (factor) in your data frame.

lapply(df, count)

Column count doesn't match value count at row 1

MySQL will also report "Column count doesn't match value count at row 1" if you try to insert multiple rows without delimiting the row sets in the VALUES section with parentheses, like so:

INSERT INTO `receiving_table`
  (1003,'George', 'Boole'),

Select from one table where not in another

You can LEFT JOIN the two tables. If there is no corresponding row in the second table, the values will be NULL.

SELECT id FROM partmaster LEFT JOIN product_details ON (...) WHERE product_details.part_num IS NULL

How to create exe of a console application

an EXE file is created as long as you build the project. you can usually find this on the debug folder of you project.

C:\Users\username\Documents\Visual Studio 2012\Projects\ProjectName\bin\Debug

Does "display:none" prevent an image from loading?

Another possibility is using a <noscript> tag and placing the image inside the <noscript> tag. Then use javascript to remove the noscript tag as you need the image. In this way you can load images on demand using progressive enhancement.

Use this polyfill I wrote to read the contents of <noscript> tags in IE8

Replace a value if null or undefined in JavaScript

ES2020 Answer

The new Nullish Coalescing Operator, is finally available on JavaScript, though browser support is limited. According to the data from caniuse, only 48.34% of browsers are supported (as of April 2020).

According to the documentation,

The nullish coalescing operator (??) is a logical operator that returns its right-hand side operand when its left-hand side operand is null or undefined, and otherwise returns its left-hand side operand.

const options={
const filter = options.filters[0] ?? '';
const filter2 = options.filters[1] ?? '';

This will ensure that both of your variables will have a fallback value of '' if filters[0] or filters[1] are null, or undefined.

Do take note that the nullish coalescing operator does not return the default value for other types of falsy value such as 0 and ''. If you wish to account for all falsy values, you should be using the OR operator ||.

How do you obtain a Drawable object from a resource id in android package?

From API 21 `getDrawable(int id)` is deprecated

So now you need to use

ResourcesCompat.getDrawable(context.getResources(), R.drawable.img_user, null)

But Best way to do is :

- You should create one common class for getting drawable and colors because if in future have any deprecation then you no need to do changes everywhere in your project.You just change in this method
object ResourceUtils {
    fun getColor(context: Context, color: Int): Int {
        return ResourcesCompat.getColor(context.getResources(), color, null)

    fun getDrawable(context: Context, drawable: Int): Drawable? {
        return ResourcesCompat.getDrawable(context.getResources(), drawable, null)

use this method like :

Drawable img=ResourceUtils.getDrawable(context, R.drawable.img_user)

JS regex: replace all digits in string

You need to add the "global" flag to your regex:

s.replace(new RegExp("[0-9]", "g"), "X")

or, perhaps prettier, using the built-in literal regexp syntax:

.replace(/[0-9]/g, "X")

Bash mkdir and subfolders


Poor mans security folder (to protect a public shared folder from little prying eyes ;) )

mkdir -p {0..9}/{0..9}/{0..9}/{0..9}

Now you can put your files in a pin numbered folder. Not exactly waterproof, but it's a barrier for the youngest.

Polygon Drawing and Getting Coordinates with Google Map API v3

If all you need is the coordinates here is a drawing tool I like to use - move the polygon or re-shape it and the coordinates will display right below the map: jsFiddle here.

Also, here is a Codepen


var bermudaTriangle;
function initialize() {
    var myLatLng = new google.maps.LatLng(33.5190755, -111.9253654);
    var mapOptions = {
        zoom: 12,
        center: myLatLng,
        mapTypeId: google.maps.MapTypeId.RoadMap

    var map = new google.maps.Map(document.getElementById('map-canvas'),

    var triangleCoords = [
        new google.maps.LatLng(33.5362475, -111.9267386),
        new google.maps.LatLng(33.5104882, -111.9627875),
        new google.maps.LatLng(33.5004686, -111.9027061)


    // Construct the polygon
    bermudaTriangle = new google.maps.Polygon({
        paths: triangleCoords,
        draggable: true,
        editable: true,
        strokeColor: '#FF0000',
        strokeOpacity: 0.8,
        strokeWeight: 2,
        fillColor: '#FF0000',
        fillOpacity: 0.35

    google.maps.event.addListener(bermudaTriangle, "dragend", getPolygonCoords);
    google.maps.event.addListener(bermudaTriangle.getPath(), "insert_at", getPolygonCoords);
    google.maps.event.addListener(bermudaTriangle.getPath(), "remove_at", getPolygonCoords);
    google.maps.event.addListener(bermudaTriangle.getPath(), "set_at", getPolygonCoords);

function getPolygonCoords() {
    var len = bermudaTriangle.getPath().getLength();
    var htmlStr = "";
    for (var i = 0; i < len; i++) {
        htmlStr += bermudaTriangle.getPath().getAt(i).toUrlValue(5) + "<br>";
    document.getElementById('info').innerHTML = htmlStr;


<body onload="initialize()">
    <h3>Drag or re-shape for coordinates to display below</h3>
    <div id="map-canvas">
    <div id="info">


#map-canvas {
    width: auto;
    height: 350px;
#info {
    position: absolute;
    font-family: arial, sans-serif;
    font-size: 18px;
    font-weight: bold;

How do I return to an older version of our code in Subversion?

Just use this line

svn update -r yourOldRevesion

You can know your current revision by using:

svn info

Remove substring from the string

If you only have one occurrence of the target string you can use:

str[target] = ''


str.sub(target, '')

If you have multiple occurrences of target use:

str.gsub(target, '')

For instance:

asdf = 'foo bar'
asdf['bar'] = ''
asdf #=> "foo "

asdf = 'foo bar'
asdf.sub('bar', '') #=> "foo "
asdf = asdf + asdf #=> "foo barfoo bar"
asdf.gsub('bar', '') #=> "foo foo "

If you need to do in-place substitutions use the "!" versions of gsub! and sub!.

Why is my power operator (^) not working?

Instead of using ^, use 'pow' function which is a predefined function which performs the Power operation and it can be used by including math.h header file.

^ This symbol performs BIT-WISE XOR operation in C, C++.

Replace a^i with pow(a,i).

C# Select elements in list as List of string

List<string> empnames = emplist.Select(e => e.Ename).ToList();

This is an example of Projection in Linq. Followed by a ToList to resolve the IEnumerable<string> into a List<string>.

Alternatively in Linq syntax (head compiled):

var empnamesEnum = from emp in emplist 
                   select emp.Ename;
List<string> empnames = empnamesEnum.ToList();

Projection is basically representing the current type of the enumerable as a new type. You can project to anonymous types, another known type by calling constructors etc, or an enumerable of one of the properties (as in your case).

For example, you can project an enumerable of Employee to an enumerable of Tuple<int, string> like so:

var tuples = emplist.Select(e => new Tuple<int, string>(e.EID, e.Ename));

How to open a link in new tab (chrome) using Selenium WebDriver?

for clicking on the link which expected to be opened from new tab use this

WebDriver driver = new ChromeDriver(); 
WebElement link=driver.findElement(By.xpath("path_to_link")); 

Actions actions = new Actions(driver); 

ArrayList<String> tab = new ArrayList<>(driver.getWindowHandles()); 

How do I convert between ISO-8859-1 and UTF-8 in Java?

Apache Commons IO Charsets class can come in handy:

String utf8String = new String(

Adding a css class to select using @Html.DropDownList()

You can simply do this:

@Html.DropDownList("PriorityID", null, new { @class="form-control"})

SQL Server - Create a copy of a database table and place it in the same database?

Copy Schema (Generate DDL) through SSMS UI

In SSMS expand your database in Object Explorer, go to Tables, right click on the table you're interested in and select Script Table As, Create To, New Query Editor Window. Do a find and replace (CTRL + H) to change the table name (i.e. put ABC in the Find What field and ABC_1 in the Replace With then click OK).

Copy Schema through T-SQL

The other answers showing how to do this by SQL also work well, but the difference with this method is you'll also get any indexes, constraints and triggers.

Copy Data

If you want to include data, after creating this table run the below script to copy all data from ABC (keeping the same ID values if you have an identity field):

set identity_insert ABC_1 on
insert into ABC_1 (column1, column2) select column1, column2 from ABC
set identity_insert ABC_1 off

Getting "Lock wait timeout exceeded; try restarting transaction" even though I'm not using a transaction

Had this same error, even though I was only updating one table with one entry, but after restarting mysql, it was resolved.

Android Starting Service at Boot Time , How to restart service class after device Reboot?

To Restart service in Android O or more ie OS >28 Use this code KOTLIN VERSION 1) Add permission in manifest

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

2) Create a Class and extend it with BroadcastReceiver

import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.os.Build
import android.util.Log
import androidx.core.content.ContextCompat

class BootCompletedReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, arg1: Intent?) {
        Log.d("BootCompletedReceiver", "starting service...")
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            ContextCompat.startForegroundService(context, Intent(context,
        } else {

3) Declare in Manifest file like this under application tag

<receiver android:name=".utils.BootCompletedReceiver" >
            <action android:name="android.intent.action.BOOT_COMPLETED" />
            <action android:name="android.intent.action.QUICKBOOT_POWERON" />

How to insert text in a td with id, using JavaScript

There are several options... assuming you found your TD by var td = document.getElementyById('myTD_ID'); you can do:

  • td.innerHTML = "mytext";

  • td.textContent= "mytext";

  • td.innerText= "mytext"; - this one may not work outside IE? Not sure

  • Use firstChild or children array as previous poster noted.

If it's just the text that needs to be changed, textContent is faster and less prone to XSS attacks (

How can I create a Java 8 LocalDate from a long Epoch time in Milliseconds?

In a specific case where your epoch seconds timestamp comes from SQL or is related to SQL somehow, you can obtain it like this:

long startDateLong = <...>

LocalDate theDate = new java.sql.Date(startDateLong).toLocalDate();

How to prevent auto-closing of console after the execution of batch file

If you are using Maven and you want to skip the typing and prevent the console from close to see the result you need to use the CALL command in the script, besides just the 'mvn clean install'.

Like this will close the console

ECHO This is the wrong exemple
mvn clean install

Like this the console will stay open

ECHO This is the right exemple
CALL mvn clean install

If you dont use the CALL command neither of the pasts exemples will work. Because for some reason the default behaviour of cmd when calling another batch file (which mvn is in this case) is to essentially replace the current process with it, unlike calling an .exe

Binary Search Tree - Java Implementation

Here is my simple binary search tree implementation in Java SE 1.8:

public class BSTNode
    int data;
    BSTNode parent;
    BSTNode left;
    BSTNode right;

    public BSTNode(int data)
    { = data;
        this.left = null;
        this.right = null;
        this.parent = null;

    public BSTNode()

public class BSTFunctions
    BSTNode ROOT;

    public BSTFunctions()
        this.ROOT = null;

    void insertNode(BSTNode node, int data)
        if (node == null)
            node = new BSTNode(data);
            ROOT = node;
        else if (data < && node.left == null)
            node.left = new BSTNode(data);
            node.left.parent = node;
        else if (data >= && node.right == null)
            node.right = new BSTNode(data);
            node.right.parent = node;
            if (data <
                insertNode(node.left, data);
                insertNode(node.right, data);

    public boolean search(BSTNode node, int data)
        if (node == null)
            return false;
        else if ( == data)
            return true;
            if (data <
                return search(node.left, data);
                return search(node.right, data);

    public void printInOrder(BSTNode node)
        if (node != null)
            System.out.print( + " - ");

    public void printPostOrder(BSTNode node)
        if (node != null)
            System.out.print( + " - ");

    public void printPreOrder(BSTNode node)
        if (node != null)
            System.out.print( + " - ");

    public static void main(String[] args)
        BSTFunctions f = new BSTFunctions();
         * Insert
        f.insertNode(f.ROOT, 20);
        f.insertNode(f.ROOT, 5);
        f.insertNode(f.ROOT, 25);
        f.insertNode(f.ROOT, 3);
        f.insertNode(f.ROOT, 7);
        f.insertNode(f.ROOT, 27);
        f.insertNode(f.ROOT, 24);

         * Print

         * Search
        System.out.println(, 27) ? "Found" : "Not Found");
        System.out.println(, 10) ? "Found" : "Not Found");

And the output is:

3 - 5 - 7 - 20 - 24 - 25 - 27 - 
3 - 7 - 5 - 24 - 27 - 25 - 20 - 
20 - 5 - 3 - 7 - 25 - 24 - 27 - 
Not Found

What is DOM element?

See that your statements refer to "elements of the DOM", which are things such as the HTML tags (A, INPUT, etc). Thse statements simply mean that multiple CSS classes may be assigned to one such element.

Tokenizing Error: java.util.regex.PatternSyntaxException, dangling metacharacter '*'

I had similar problem with regex = "?". It happens for all special characters that have some meaning in a regex. So you need to have "\\" as a prefix to your regex.

String [] separado = line.split("\\*");

Can't install gems on OS X "El Capitan"

You might have two options:

  1. If you've installed ruby and rails, you can first try running the command:
    rvm fix-permissions 
  2. You can uninstall ruby completely, and reinstall in your ~ directory aka your home directory.

If you're using homebrew the command is:

brew uninstall ruby

For rails uninstall without homebrew the command is:

rvm remove

This should reinstall the latest ruby by running command:

curl -L | bash -s stable --rails<br>

Mac has 2.6.3 factory installed, and it's required... if not run this command:

rvm install "ruby-2.6.3"

and then:

gem install rails

You'll get a few error messages at the end saying you have to add some other bundles...
Just make sure you're in the home ~ directory when you're installing so the permissions won't be an issue, but just in case...

I again ran:

rvm fix-permissions


rvm debug

which told me I had to download yarn, I didn't save the output for it. Basically I did whatever the prompt told me to do if it had to do with my OS.


Creating a comma separated list from IList<string> or IEnumerable<string>

FYI, the .NET 4.0 version of string.Join() has some extra overloads, that work with IEnumerable instead of just arrays, including one that can deal with any type T:

public static string Join(string separator, IEnumerable<string> values)
public static string Join<T>(string separator, IEnumerable<T> values)

jQuery - Add ID instead of Class

Try this:

$('element').attr('id', 'value');

So it becomes;

$(function() {
    $('span .breadcrumb').each(function(){
        $('#nav').attr('id', $(this).text());
        $('#container').attr('id', $(this).text());
        $('.stretch_footer').attr('id', $(this).text())
        $('#footer').attr('id', $(this).text());

So you are changing/overwriting the id of three elements and adding an id to one element. You can modify as per you needs...

Invoke-WebRequest, POST with parameters

For some picky web services, the request needs to have the content type set to JSON and the body to be a JSON string. For example:

Invoke-WebRequest -UseBasicParsing -ContentType "application/json" -Method POST -Body "{ 'ItemID':3661515, 'Name':'test'}"

or the equivalent for XML, etc.

Copy folder recursively in Node.js

The fs-extra module works like a charm.

Install fs-extra:

$ npm install fs-extra

The following is the program to copy a source directory to a destination directory.

// Include the fs-extra package
var fs = require("fs-extra");

var source = 'folderA'
var destination = 'folderB'

// Copy the source folder to the destination
fs.copy(source, destination, function (err) {
    if (err){
        console.log('An error occurred while copying the folder.')
        return console.error(err)
    console.log('Copy completed!')



Example: Node.js Tutorial - Node.js Copy a Folder

ActivityCompat.requestPermissions not showing dialog box

I came across this problem in Samsung S8 and N8 (havent found in any other)

so the problem is in the manifest file uses-permission

<uses-permission android:name="android.permission.CAMERA"
android:requiredFeature="true" />

For some reason, the attribute android:requiredFeature is the culprit. and I haven't found the explanation on why.

to solve simply remove it,

<uses-permission android:name="android.permission.CAMERA" />

Easiest way to copy a table from one database to another?

use below steps to copy and insert some columns from one database table to another database table-

  1. CREATE TABLE tablename ( columnname datatype (size), columnname datatype (size));

2.INSERT INTO db2.tablename SELECT columnname1,columnname2 FROM db1.tablename;

Concatenate two string literals

const string message = "Hello" + ",world" + exclam;

The + operator has left-to-right associativity, so the equivalent parenthesized expression is:

const string message = (("Hello" + ",world") + exclam);

As you can see, the two string literals "Hello" and ",world" are "added" first, hence the error.

One of the first two strings being concatenated must be a std::string object:

const string message = string("Hello") + ",world" + exclam;

Alternatively, you can force the second + to be evaluated first by parenthesizing that part of the expression:

const string message = "Hello" + (",world" + exclam);

It makes sense that your first example (hello + ",world" + "!") works because the std::string (hello) is one of the arguments to the leftmost +. That + is evaluated, the result is a std::string object with the concatenated string, and that resulting std::string is then concatenated with the "!".

As for why you can't concatenate two string literals using +, it is because a string literal is just an array of characters (a const char [N] where N is the length of the string plus one, for the null terminator). When you use an array in most contexts, it is converted into a pointer to its initial element.

So, when you try to do "Hello" + ",world", what you're really trying to do is add two const char*s together, which isn't possible (what would it mean to add two pointers together?) and if it was it wouldn't do what you wanted it to do.

Note that you can concatenate string literals by placing them next to each other; for example, the following two are equivalent:

"Hello" ",world"

This is useful if you have a long string literal that you want to break up onto multiple lines. They have to be string literals, though: this won't work with const char* pointers or const char[N] arrays.

Toggle show/hide on click with jQuery

<!DOCTYPE html>
<script src="</script>        <script>
<p>Welcome !!!</p>
<button>Toggle between hide() and show()</button>

Location for session files in Apache/PHP

First check the value of session.save_path using ini_get('session.save_path') or phpinfo(). If that is non-empty, then it will show where the session files are saved. In many scenarios it is empty by default, in which case read on:

On Ubuntu or Debian machines, if session.save_path is not set, then session files are saved in /var/lib/php5.

On RHEL and CentOS systems, if session.save_path is not set, session files will be saved in /var/lib/php/session

I think that if you compile PHP from source, then when session.save_path is not set, session files will be saved in /tmp (I have not tested this myself though).

Android ListView Text Color

You have to define the text color in the layout *simple_list_item_1* that defines the layout of each of your items.

You set the background color of the LinearLayout and not of the ListView. The background color of the child items of the LinearLayout are transparent by default (in most cases).

And you set the black text color for the TextView that is not part of your ListView. It is an own item (child item of the LinearLayout) here.

C++ Returning reference to local variable

A good thing to remember are these simple rules, and they apply to both parameters and return types...

  • Value - makes a copy of the item in question.
  • Pointer - refers to the address of the item in question.
  • Reference - is literally the item in question.

There is a time and place for each, so make sure you get to know them. Local variables, as you've shown here, are just that, limited to the time they are locally alive in the function scope. In your example having a return type of int* and returning &i would have been equally incorrect. You would be better off in that case doing this...

void func1(int& oValue)
    oValue = 1;

Doing so would directly change the value of your passed in parameter. Whereas this code...

void func1(int oValue)
    oValue = 1;

would not. It would just change the value of oValue local to the function call. The reason for this is because you'd actually be changing just a "local" copy of oValue, and not oValue itself.

JavaScript: client-side vs. server-side validation

If you are doing light validation, it is best to do it on the client. It will save the network traffic which will help your server perform better. If if it complicated validation that involves pulling data from a database or something, like passwords, then it best to do it on the server where the data can be securely checked.

Could not find server 'server name' in sys.servers. SQL Server 2014

I had the problem due to an extra space in the name of the linked server. "SERVER1, 1234" instead of "SERVER1,1234"

Android: converting String to int

// Convert String to Integer

// String s = "fred";  // use this if you want to test the exception below

String s = "100"; 
  // the String to int conversion happens here
  int i = Integer.parseInt(s.trim());

  // print out the value after the conversion
  System.out.println("int i = " + i);
catch (NumberFormatException nfe)
  System.out.println("NumberFormatException: " + nfe.getMessage());

How to calculate the number of days between two dates?

Here is my implementation:

function daysBetween(one, another) {
  return Math.round(Math.abs((+one) - (+another))/8.64e7);

+<date> does the type coercion to the integer representation and has the same effect as <date>.getTime() and 8.64e7 is the number of milliseconds in a day.

CSV new-line character seen in unquoted field error

I realize this is an old post, but I ran into the same problem and don't see the correct answer so I will give it a try

Python Error:

_csv.Error: new-line character seen in unquoted field

Caused by trying to read Macintosh (pre OS X formatted) CSV files. These are text files that use CR for end of line. If using MS Office make sure you select either plain CSV format or CSV (MS-DOS). Do not use CSV (Macintosh) as save-as type.

My preferred EOL version would be LF (Unix/Linux/Apple), but I don't think MS Office provides the option to save in this format.

Check last modified date of file in C#

Be aware that the function File.GetLastWriteTime does not always work as expected, the values are sometimes not instantaneously updated by the OS. You may get an old Timestamp, even if the file has been modified right before.

The behaviour may vary between OS versions. For example, this unit test worked well every time on my developer machine, but it always fails on our build server.

  public void TestLastModifiedTimeStamps()
     var tempFile = Path.GetTempFileName();
     var lastModified = File.GetLastWriteTime(tempFile);
     using (new FileStream(tempFile, FileMode.Create, FileAccess.Write, FileShare.None))

     Assert.AreNotEqual(lastModified, File.GetLastWriteTime(tempFile));

See File.GetLastWriteTime seems to be returning 'out of date' value

Your options:

a) live with the occasional omissions.

b) Build up an active component realising the observer pattern (eg. a tcp server client structure), communicating the changes directly instead of writing / reading files. Fast and flexible, but another dependency and a possible point of failure (and some work, of course).

c) Ensure the signalling process by replacing the content of a dedicated signal file that other processes regularly read. It´s not that smart as it´s a polling procedure and has a greater overhead than calling File.GetLastWriteTime, but if not checking the content from too many places too often, it will do the work.

/// <summary>
/// type to set signals or check for them using a central file 
/// </summary>
public class FileSignal
    /// <summary>
    /// path to the central file for signal control
    /// </summary>
    public string FilePath { get; private set; }

    /// <summary>
    /// numbers of retries when not able to retrieve (exclusive) file access
    /// </summary>
    public int MaxCollisions { get; private set; }

    /// <summary>
    /// timespan to wait until next try
    /// </summary>
    public TimeSpan SleepOnCollisionInterval { get; private set; }

    /// <summary>
    /// Timestamp of the last signal
    /// </summary>
    public DateTime LastSignal { get; private set; }

    /// <summary>
    /// constructor
    /// </summary>
    /// <param name="filePath">path to the central file for signal control</param>
    /// <param name="maxCollisions">numbers of retries when not able to retrieve (exclusive) file access</param>
    /// <param name="sleepOnCollisionInterval">timespan to wait until next try </param>
    public FileSignal(string filePath, int maxCollisions, TimeSpan sleepOnCollisionInterval)
        FilePath = filePath;
        MaxCollisions = maxCollisions;
        SleepOnCollisionInterval = sleepOnCollisionInterval;
        LastSignal = GetSignalTimeStamp();

    /// <summary>
    /// constructor using a default value of 50 ms for sleepOnCollisionInterval
    /// </summary>
    /// <param name="filePath">path to the central file for signal control</param>
    /// <param name="maxCollisions">numbers of retries when not able to retrieve (exclusive) file access</param>        
    public FileSignal(string filePath, int maxCollisions): this (filePath, maxCollisions, TimeSpan.FromMilliseconds(50))

    /// <summary>
    /// constructor using a default value of 50 ms for sleepOnCollisionInterval and a default value of 10 for maxCollisions
    /// </summary>
    /// <param name="filePath">path to the central file for signal control</param>        
    public FileSignal(string filePath) : this(filePath, 10)

    private Stream GetFileStream(FileAccess fileAccess)
        var i = 0;
        while (true)
                return new FileStream(FilePath, FileMode.Create, fileAccess, FileShare.None);
            catch (Exception e)
                if (i >= MaxCollisions)
                    throw e;

    private DateTime GetSignalTimeStamp()
        if (!File.Exists(FilePath))
            return DateTime.MinValue;
        using (var stream = new FileStream(FilePath, FileMode.Open, FileAccess.Read, FileShare.None))
            if(stream.Length == 0)
                return DateTime.MinValue;
            using (var reader = new BinaryReader(stream))
                return DateTime.FromBinary(reader.ReadInt64());

    /// <summary>
    /// overwrites the existing central file and writes the current time into it.
    /// </summary>
    public void Signal()
        LastSignal = DateTime.Now;
        using (var stream = new FileStream(FilePath, FileMode.Create, FileAccess.Write, FileShare.None))
            using (var writer = new BinaryWriter(stream))

    /// <summary>
    /// returns true if the file signal has changed, otherwise false.
    /// </summary>        
    public bool CheckIfSignalled()
        var signal = GetSignalTimeStamp();
        var signalTimestampChanged = LastSignal != signal;
        LastSignal = signal;
        return signalTimestampChanged;

Some tests for it:

    public void TestSignal()
        var fileSignal = new FileSignal(Path.GetTempFileName());
        var fileSignal2 = new FileSignal(fileSignal.FilePath);
        Assert.AreEqual(fileSignal.LastSignal, fileSignal2.LastSignal);
        Assert.AreNotEqual(fileSignal.LastSignal, fileSignal2.LastSignal);
        Assert.AreEqual(fileSignal.LastSignal, fileSignal2.LastSignal);

cannot convert 'std::basic_string<char>' to 'const char*' for argument '1' to 'int system(const char*)'

The addition of a string literal with an std::string yields another std::string. system expects a const char*. You can use std::string::c_str() for that:

string name = "john";
string tmp = " quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '"+name+".jpg'"

What is the pythonic way to unpack tuples?

Generally, you can use the func(*tuple) syntax. You can even pass a part of the tuple, which seems like what you're trying to do here:

t = (2010, 10, 2, 11, 4, 0, 2, 41, 0)
dt = datetime.datetime(*t[0:7])

This is called unpacking a tuple, and can be used for other iterables (such as lists) too. Here's another example (from the Python tutorial):

>>> range(3, 6)             # normal call with separate arguments
[3, 4, 5]
>>> args = [3, 6]
>>> range(*args)            # call with arguments unpacked from a list
[3, 4, 5]

Sieve of Eratosthenes - Finding Primes Python

I figured it must be possible to simply use the empty list as the terminating condition for the loop and came up with this:

limit = 100
ints = list(range(2, limit))   # Will end up empty

while len(ints) > 0:
    prime = ints[0]
    print prime
    i = 2
    multiple = prime * i
    while multiple <= limit:
        if multiple in ints:
        i += 1
        multiple = prime * i

WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for jquery

The exception indicates a problem with the unobtrusive JavaScript validation mode. This issue is not Sitefinity specific and occurs in any standard ASP.NET applications when the project targets .NET 4.5 framework and the pre-4.5 validation is not enabled in the web.config file.

Open the web.config file and make sure that there is a ValidationSettings:UnobtrusiveValidationMode in the app settings:

  <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />

connecting to phpMyAdmin database with PHP/MySQL

$db = new mysqli('Server_Name', 'Name', 'password', 'database_name');

php return 500 error but no error log

Here is another reason why errors might not be visible:

I had the same issue. In my case, I had copied the source from a production environment. Hence the ENVIRONMENT variable defined in index.php was set to 'production'. This caused error_reporting to be set to 0 (no logging). Just set it to 'development' and you should start seeing error messages in apache log.

Turned out the 500 was due to a semi colon missing in database config :-)

Can I connect to SQL Server using Windows Authentication from Java EE webapp?

look at

What is the URL format used by jTDS?

The URL format for jTDS is:


... domain Specifies the Windows domain to authenticate in. If present and the user name and password are provided, jTDS uses Windows (NTLM) authentication instead of the usual SQL Server authentication (i.e. the user and password provided are the domain user and password). This allows non-Windows clients to log in to servers which are only configured to accept Windows authentication.

If the domain parameter is present but no user name and password are provided, jTDS uses its native Single-Sign-On library and logs in with the logged Windows user's credentials (for this to work one would obviously need to be on Windows, logged into a domain, and also have the SSO library installed -- consult README.SSO in the distribution on how to do this).

Highlighting Text Color using Html.fromHtml() in Android?

Adding also Kotlin version with:

  • getting text from resources (strings.xml)
  • getting color from resources (colors.xml)
  • "fetching HEX" moved as extension
fun getMulticolorSpanned(): Spanned {
    // Get text from resources
    val text: String = getString(R.string.your_text_from_resources)

    // Get color from resources and parse it to HEX (RGB) value
    val warningHexColor = getHexFromColors(R.color.your_error_color)

    // Use above string & color in HTML
    val html = "<string>$text<span style=\"color:#$warningHexColor;\">*</span></string>"

    // Parse HTML (base on API version)
    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        Html.fromHtml(html, Html.FROM_HTML_MODE_LEGACY)
    } else {

And Kotlin extension (with removing alpha):

fun Context.getHexFromColors(
    colorRes: Int
): String {
    val labelColor: Int = ContextCompat.getColor(this, colorRes)
    return String.format("%X", labelColor).substring(2)



Extract / Identify Tables from PDF python

I'd just like to add to the very helpful answer from Kurt Pfeifle - there is now a Python wrapper for Tabula, and this seems to work very well so far:

This will convert your PDF table to a Pandas data frame. You can also set the area in x,y co-ordinates which is obviously very handy for irregular data.

Using Mysql WHERE IN clause in codeigniter

Try this one:

$this->db->where_in("(SELECT trans_id FROM myTable WHERE code = 'B')");
$this->db->where('code !=', 'B');

Note: $this->db->select("*"); is optional when you are selecting all columns from table

Create a CSV File for a user in PHP

    // Connect to database
    $result = mysql_query("select id
    from tablename
    where shid=3");
    list($DBshid) = mysql_fetch_row($result);

    Write date to CSV file

    $_file = 'show.csv';
    $_fp = @fopen( $_file, 'wb' );

    $result = mysql_query("select name,compname,job_title,email_add,phone,url from UserTables where id=3");

    while (list( $Username, $Useremail_add, $Userphone, $Userurl) = mysql_fetch_row($result))
        $_csv_data = $Username.','.$Useremail_add.','.$Userphone.','.$Userurl . "\n";
        @fwrite( $_fp, $_csv_data);
    @fclose( $_fp );

In Jinja2, how do you test if a variable is undefined?

{% if variable is defined %} works to check if something is undefined.

You can get away with using {% if not var1 %} if you default your variables to False eg

class MainHandler(BaseHandler):
    def get(self):
        var1 = self.request.get('var1', False)

Making div content responsive

try this css:

/* Show in default resolution screen*/
#container2 {
width: 960px;
position: relative;
margin:0 auto;
line-height: 1.4em;

/* If in mobile screen with maximum width 479px. The iPhone screen resolution is 320x480 px (except iPhone4, 640x960) */    
@media only screen and (max-width: 479px){
    #container2 { width: 90%; }

Here the demo:

Extracting Ajax return data in jQuery

You can use .filter on a jQuery object that was created from the response:

success: function(data){
    //Create jQuery object from the response HTML.
    var $response=$(data);

    //Query the jQuery object for the values
    var oneval = $response.filter('#one').text();
    var subval = $response.filter('#sub').text();

How to get html to print return value of javascript function?

There are some options to do that.

One would be:


Other would be appending some element in your document this way:

var span = document.createElement("span");

Or just:


If you're using jQuery, you can do this:


How to store Node.js deployment settings/configuration files?

I use a package.json for my packages and a config.js for my configuration, which looks like:

var config = {};

config.twitter = {};
config.redis = {};
config.web = {};

config.default_stuff =  ['red','green','blue','apple','yellow','orange','politics'];
config.twitter.user_name = process.env.TWITTER_USER || 'username';
config.twitter.password=  process.env.TWITTER_PASSWORD || 'password';
config.redis.uri = process.env.DUOSTACK_DB_REDIS; = 'hostname';
config.redis.port = 6379;
config.web.port = process.env.WEB_PORT || 9980;

module.exports = config;

I load the config from my project:

var config = require('./config');

and then I can access my things from config.db_host, config.db_port, etc... This lets me either use hardcoded parameters, or parameters stored in environmental variables if I don't want to store passwords in source control.

I also generate a package.json and insert a dependencies section:

"dependencies": {
  "cradle": "0.5.5",
  "jade": "0.10.4",
  "redis": "0.5.11",
  "": "0.6.16",
  "twitter-node": "0.0.2",
  "express": "2.2.0"

When I clone the project to my local machine, I run npm install to install the packages. More info on that here.

The project is stored in GitHub, with remotes added for my production server.

How Spring Security Filter Chain works

Spring security is a filter based framework, it plants a WALL(HttpFireWall) before your application in terms of proxy filters or spring managed beans. Your request has to pass through multiple filters to reach your API.

Sequence of execution in Spring Security

  1. WebAsyncManagerIntegrationFilter Provides integration between the SecurityContext and Spring Web's WebAsyncManager.

  2. SecurityContextPersistenceFilter This filter will only execute once per request, Populates the SecurityContextHolder with information obtained from the configured SecurityContextRepository prior to the request and stores it back in the repository once the request has completed and clearing the context holder.
    Request is checked for existing session. If new request, SecurityContext will be created else if request has session then existing security-context will be obtained from respository.

  3. HeaderWriterFilter Filter implementation to add headers to the current response.

  4. LogoutFilter If request url is /logout(for default configuration) or if request url mathces RequestMatcher configured in LogoutConfigurer then

    • clears security context.
    • invalidates the session
    • deletes all the cookies with cookie names configured in LogoutConfigurer
    • Redirects to default logout success url / or logout success url configured or invokes logoutSuccessHandler configured.
  5. UsernamePasswordAuthenticationFilter

    • For any request url other than loginProcessingUrl this filter will not process further but filter chain just continues.
    • If requested URL is matches(must be HTTP POST) default /login or matches .loginProcessingUrl() configured in FormLoginConfigurer then UsernamePasswordAuthenticationFilter attempts authentication.
    • default login form parameters are username and password, can be overridden by usernameParameter(String), passwordParameter(String).
    • setting .loginPage() overrides defaults
    • While attempting authentication
      • an Authentication object(UsernamePasswordAuthenticationToken or any implementation of Authentication in case of your custom auth filter) is created.
      • and authenticationManager.authenticate(authToken) will be invoked
      • Note that we can configure any number of AuthenticationProvider authenticate method tries all auth providers and checks any of the auth provider supports authToken/authentication object, supporting auth provider will be used for authenticating. and returns Authentication object in case of successful authentication else throws AuthenticationException.
    • If authentication success session will be created and authenticationSuccessHandler will be invoked which redirects to the target url configured(default is /)
    • If authentication failed user becomes un-authenticated user and chain continues.
  6. SecurityContextHolderAwareRequestFilter, if you are using it to install a Spring Security aware HttpServletRequestWrapper into your servlet container

  7. AnonymousAuthenticationFilter Detects if there is no Authentication object in the SecurityContextHolder, if no authentication object found, creates Authentication object (AnonymousAuthenticationToken) with granted authority ROLE_ANONYMOUS. Here AnonymousAuthenticationToken facilitates identifying un-authenticated users subsequent requests.

Debug logs
DEBUG - /app/admin/app-config at position 9 of 12 in additional filter chain; firing Filter: 'AnonymousAuthenticationFilter'
DEBUG - Populated SecurityContextHolder with anonymous token: ' Principal: anonymousUser; Credentials: [PROTECTED]; Authenticated: true; Details: RemoteIpAddress: 0:0:0:0:0:0:0:1; SessionId: null; Granted Authorities: ROLE_ANONYMOUS' 
  1. ExceptionTranslationFilter, to catch any Spring Security exceptions so that either an HTTP error response can be returned or an appropriate AuthenticationEntryPoint can be launched

  2. FilterSecurityInterceptor
    There will be FilterSecurityInterceptor which comes almost last in the filter chain which gets Authentication object from SecurityContext and gets granted authorities list(roles granted) and it will make a decision whether to allow this request to reach the requested resource or not, decision is made by matching with the allowed AntMatchers configured in HttpSecurityConfiguration.

Consider the exceptions 401-UnAuthorized and 403-Forbidden. These decisions will be done at the last in the filter chain

  • Un authenticated user trying to access public resource - Allowed
  • Un authenticated user trying to access secured resource - 401-UnAuthorized
  • Authenticated user trying to access restricted resource(restricted for his role) - 403-Forbidden

Note: User Request flows not only in above mentioned filters, but there are others filters too not shown here.(ConcurrentSessionFilter,RequestCacheAwareFilter,SessionManagementFilter ...)
It will be different when you use your custom auth filter instead of UsernamePasswordAuthenticationFilter.
It will be different if you configure JWT auth filter and omit .formLogin() i.e, UsernamePasswordAuthenticationFilter it will become entirely different case.

Just For reference. Filters in spring-web and spring-security
Note: refer package name in pic, as there are some other filters from orm and my custom implemented filter.

enter image description here

From Documentation ordering of filters is given as

  • ChannelProcessingFilter
  • ConcurrentSessionFilter
  • SecurityContextPersistenceFilter
  • LogoutFilter
  • X509AuthenticationFilter
  • AbstractPreAuthenticatedProcessingFilter
  • CasAuthenticationFilter
  • UsernamePasswordAuthenticationFilter
  • ConcurrentSessionFilter
  • OpenIDAuthenticationFilter
  • DefaultLoginPageGeneratingFilter
  • DefaultLogoutPageGeneratingFilter
  • ConcurrentSessionFilter
  • DigestAuthenticationFilter
  • BearerTokenAuthenticationFilter
  • BasicAuthenticationFilter
  • RequestCacheAwareFilter
  • SecurityContextHolderAwareRequestFilter
  • JaasApiIntegrationFilter
  • RememberMeAuthenticationFilter
  • AnonymousAuthenticationFilter
  • SessionManagementFilter
  • ExceptionTranslationFilter
  • FilterSecurityInterceptor
  • SwitchUserFilter

You can also refer
most common way to authenticate a modern web app?
difference between authentication and authorization in context of Spring Security?

How to update Android Studio automatically?

These steps are for the people who already have Android Studio installed on their Windows machine >>>

Steps to download the update:

  1. Google for “Update android studio”
  2. Choose the result from “”
  3. Download the zip file (it’s around 500 MB).

Steps to install Android Studio from a .zip folder:

  1. Open the .zip folder using Windows Explorer.
  2. click on 'Extract all' (or 'Extract all files') option in the ribbon.
  3. Go to the extract location. And then to android-studio\bin and run studio.exe ifyou’re on 32bit OS, or studio64.exe if you’re on 64bit OS.

By then, the Andriod Studio should open and configure your uppdates enter image description here

Android: Rotate image in imageview by an angle

This is my implementation of RotatableImageView. Usage is very easy: just copy attrs.xml and into your project and add RotatableImageView to your layout. Set desired rotation angle using example:angle parameter.

<FrameLayout xmlns:android=""

        example:angle="180" />

If you have some problems with displaying image, try change code in RotatableImageView.onDraw() method or use draw() method instead.

Grant Select on all Tables Owned By Specific User

Well, it's not a single statement, but it's about as close as you can get with oracle:

   FOR R IN (SELECT owner, table_name FROM all_tables WHERE owner='TheOwner') LOOP
      EXECUTE IMMEDIATE 'grant select on '||R.owner||'.'||R.table_name||' to TheUser';

Removing u in list

arr = [str(r) for r in arr]

This basically converts all your elements in string. Hence removes the encoding. Hence the u which represents encoding gets removed Will do the work easily and efficiently

Difference between Spring MVC and Spring Boot

  • Using spring boot you will no need to build configuration. This will have done automatically when you create project.

  • If you use spring MVC you need to build configuration yourself. It is more complicated, but it is crucial.

SSRS - Checking whether the data is null

try like this

= IIF( MAX( iif( IsNothing(Fields!.Reading.Value ), -1, Fields!.Reading.Value ) ) = -1, "",  FormatNumber(  MAX( iif( IsNothing(Fields!.Reading.Value ), -1, Fields!.Reading.Value ), "CellReading_Reading"),3)) )

How to test abstract class in Java with JUnit?

If you need a solution anyway (e.g. because you have too many implementations of the abstract class and the testing would always repeat the same procedures) then you could create an abstract test class with an abstract factory method which will be excuted by the implementation of that test class. This examples works or me with TestNG:

The abstract test class of Car:

abstract class CarTest {

// the factory method
abstract Car createCar(int speed, int fuel);

// all test methods need to make use of the factory method to create the instance of a car
public void testGetSpeed() {
    Car car = createCar(33, 44);
    assertEquals(car.getSpeed(), 33);

Implementation of Car

class ElectricCar extends Car {

    private final int batteryCapacity;

    public ElectricCar(int speed, int fuel, int batteryCapacity) {
        super(speed, fuel);
        this.batteryCapacity = batteryCapacity;


Unit test class ElectricCarTest of the Class ElectricCar:

class ElectricCarTest extends CarTest {

    // implementation of the abstract factory method
    Car createCar(int speed, int fuel) {
        return new ElectricCar(speed, fuel, 0);

    // here you cann add specific test methods

How do you close/hide the Android soft keyboard using Java?

public static void closeInput(final View caller) {  
    caller.postDelayed(new Runnable() {
        public void run() {
            InputMethodManager imm = (InputMethodManager) caller.getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(caller.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
    }, 100);

This method generally works, but there is one condition: you can't have android:windowSoftInputMode="any_of_these" set

Loading all images using imread from a given folder

I used skimage. You can create a collection and access elements the standard way, i.e. col[index]. This will give you the RGB values.

from import imread_collection

#your path 
col_dir = 'cats/*.jpg'

#creating a collection with the available images
col = imread_collection(col_dir)

How do I create a user account for basic authentication?

Just to add a note, since I can't comment without 50+ rep...

If you have FIPS enabled on the server, it doesn't allow you to create users. Because IIS v8 (and lower I would imagine) does not use FIPS encryption algorithms. It would be great if it supported it , because obviously a user account in windows is insecure compared to a virtual user mapped to an isolated folder. Too bad.

enter image description here

C#: Dynamic runtime cast

Try a generic:

public static T CastTo<T>(this dynamic obj, bool safeCast) where T:class
      return (T)obj;
      if(safeCast) return null;
      else throw;

This is in extension method format, so its usage would be as if it were a member of dynamic objects:

dynamic myDynamic = new Something();
var typedObject = myDynamic.CastTo<Something>(false);

EDIT: Grr, didn't see that. Yes, you could reflectively close the generic, and it wouldn't be hard to hide in a non-generic extension method:

public static dynamic DynamicCastTo(this dynamic obj, Type castTo, bool safeCast)
   MethodInfo castMethod = this.GetType().GetMethod("CastTo").MakeGenericMethod(castTo);
   return castMethod.Invoke(null, new object[] { obj, safeCast });

I'm just not sure what you'd get out of this. Basically you're taking a dynamic, forcing a cast to a reflected type, then stuffing it back in a dynamic. Maybe you're right, I shouldn't ask. But, this'll probably do what you want. Basically when you go into dynamic-land, you lose the need to perform most casting operations as you can discover what an object is and does through reflective methods or trial and error, so there aren't many elegant ways to do this.

How to use double or single brackets, parentheses, curly braces

Parentheses in function definition

Parentheses () are being used in function definition:

function_name () { command1 ; command2 ; }

That is the reason you have to escape parentheses even in command parameters:

$ echo (
bash: syntax error near unexpected token `newline'

$ echo \(

$ echo () { command echo The command echo was redefined. ; }
$ echo anything
The command echo was redefined.

How to strip HTML tags from a string in SQL Server?

There is a UDF that will do that described here:

User Defined Function to Strip HTML

    DECLARE @Start INT
    DECLARE @Length INT
    SET @Start = CHARINDEX('<',@HTMLText)
    SET @End = CHARINDEX('>',@HTMLText,CHARINDEX('<',@HTMLText))
    SET @Length = (@End - @Start) + 1
    WHILE @Start > 0 AND @End > 0 AND @Length > 0
        SET @HTMLText = STUFF(@HTMLText,@Start,@Length,'')
        SET @Start = CHARINDEX('<',@HTMLText)
        SET @End = CHARINDEX('>',@HTMLText,CHARINDEX('<',@HTMLText))
        SET @Length = (@End - @Start) + 1

Edit: note this is for SQL Server 2005, but if you change the keyword MAX to something like 4000, it will work in SQL Server 2000 as well.

How do I calculate a trendline for a graph?

OK, here's my best pseudo math:

The equation for your line is:

Y = a + bX


b = (sum(x*y) - sum(x)sum(y)/n) / (sum(x^2) - sum(x)^2/n)

a = sum(y)/n - b(sum(x)/n)

Where sum(xy) is the sum of all x*y etc. Not particularly clear I concede, but it's the best I can do without a sigma symbol :)

... and now with added Sigma

b = (Σ(xy) - (ΣxΣy)/n) / (Σ(x^2) - (Σx)^2/n)

a = (Σy)/n - b((Σx)/n)

Where Σ(xy) is the sum of all x*y etc. and n is the number of points

Chrome sendrequest error: TypeError: Converting circular structure to JSON

This might not be related answer, but this link Detecting and fixing circular references in JavaScript might helpful to detect objects which are causing circular dependency.

How do I close an open port from the terminal on the Mac?

try below, assuming running port is 8000:

free-port() { kill "$(lsof -t -i :8000)"; }

I found the reference here

Outlets cannot be connected to repeating content iOS

Create a table view cell subclass and set it as the class of the prototype. Add the outlets to that class and connect them. Now when you configure the cell you can access the outlets.

How to check "hasRole" in Java Code with Spring Security?

Better late then never, let me put in my 2 cents worth.

In JSF world, within my managed bean, I did the following:

HttpServletRequest req = (HttpServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest();
SecurityContextHolderAwareRequestWrapper sc = new SecurityContextHolderAwareRequestWrapper(req, "");

As mentioned above, my understanding is that it can be done the long winded way as followed:

Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal();
UserDetails userDetails = null;
if (principal instanceof UserDetails) {
    userDetails = (UserDetails) principal;
    Collection  authorities = userDetails.getAuthorities();

Stop Visual Studio from mixing line endings in files

With VS2010+ there is a plugin solution: Line Endings Unifier.

With the plugin installed you can right click files and folders in the solution explorer and invoke the menu item Unify Line Endings in this file

Configuration for this is available via

Tools -> Options -> Line Endings Unifier.

The default file extension list that is included is pretty narrow:

 .cpp; .c; .h; .hpp; .cs; .js; .vb; .txt;

Might want to use something like:

 .cpp; .c; .h; .hpp; .cs; .js; .vb; .txt; .scss; .coffee; .ts; .jsx; .markdown; .config

Dynamically fill in form values with jQuery

Assuming this example HTML:

<input type="text" name="email" id="email" />
<input type="text" name="first_name" id="first_name" />
<input type="text" name="last_name" id="last_name" />

You could have this javascript:

$("#email").bind("change", function(e){
  $.getJSON("" + $("#email").val(),
          $.each(data, function(i,item){
            if (item.field == "first_name") {
            } else if (item.field == "last_name") {

Then just you have a PHP script (in this case lookup.php) that takes an email in the query string and returns a JSON formatted array back with the values you want to access. This is the part that actually hits the database to look up the values:

//look up the record based on email and get the firstname and lastname

//build the JSON array for return
$json = array(array('field' => 'first_name', 
                    'value' => $firstName), 
              array('field' => 'last_name', 
                    'value' => $last_name));
echo json_encode($json );

You'll want to do other things like sanitize the email input, etc, but should get you going in the right direction.

Back to previous page with header( "Location: " ); in PHP

Its so simple just use this


Its working fine for me

What is the difference between CSS and SCSS?

Variable definitions right:

$      => SCSS, SASS
--     => CSS
@      => LESS

All answers is good but question a little different than answers

"about Sass. How is SCSS different from CSS" : scss is well formed CSS3 syntax. uses sass preprocessor to create that.

and if I use SCSS instead of CSS will it work the same? yes. if your ide supports sass preprocessor. than it will work same.

Sass has two syntaxes. The most commonly used syntax is known as “SCSS” (for “Sassy CSS”), and is a superset of CSS3’s syntax. This means that every valid CSS3 stylesheet is valid SCSS as well. SCSS files use the extension .scss.

The second, older syntax is known as the indented syntax (or just “.sass”). Inspired by Haml’s terseness, it’s intended for people who prefer conciseness over similarity to CSS. Instead of brackets and semicolons, it uses the indentation of lines to specify blocks. Files in the indented syntax use the extension .sass.

  • Furher Information About:

What Is A CSS Preprocessor?

CSS in itself is devoid of complex logic and functionality which is required to write reusable and organized code. As a result, a developer is bound by limitations and would face extreme difficulty in code maintenance and scalability, especially when working on large projects involving extensive code and multiple CSS stylesheets. This is where CSS Preprocessors come to the rescue.

A CSS Preprocessor is a tool used to extend the basic functionality of default vanilla CSS through its own scripting language. It helps us to use complex logical syntax like – variables, functions, mixins, code nesting, and inheritance to name a few, supercharging your vanilla CSS. By using CSS Preprocessors, you can seamlessly automate menial tasks, build reusable code snippets, avoid code repetition and bloating and write nested code blocks that are well organized and easy to read. However, browsers can only understand native vanilla CSS code and will be unable to interpret the CSS Preprocessor syntax. Therefore, the complex and advanced Preprocessor syntax needs to be first compiled into native CSS syntax which can then be interpreted by the browsers to avoid cross browser compatibility issues. While different Preprocessors have their own unique syntaxes, eventually all of them are compiled to the same native CSS code.

Moving forward in the article, we will take a look at the 3 most popular CSS Preprocessors currently being used by developers around the world i.e Sass, LESS, and Stylus. Before you decide the winner between Sass vs LESS vs Stylus, let us get to know them in detail first.

Sass – Syntactically Awesome Style Sheets

Sass is the acronym for “Syntactically Awesome Style Sheets”. Sass is not only the most popular CSS Preprocessor in the world but also one of the oldest, launched in 2006 by Hampton Catlin and later developed by Natalie Weizenbaum. Although Sass is written in Ruby language, a Precompiler LibSass allows Sass to be parsed in other languages and decouple it from Ruby. Sass has a massive active community and extensive learning resources available on the net for beginners. Thanks to its maturity, stability and powerful logical prowess, Sass has established itself to the forefront of CSS Preprocessor ahead of its rival peers.

Sass can be written in 2 syntaxes either using Sass or SCSS. What is the difference between the two? Let’s find out.

Syntax Declaration: Sass vs SCSS

  • SCSS stands for Sassy CSS. Unlike Sass, SCSS is not based on indentation.
  • .sass extension is used as original syntax for Sass, while SCSS offers a newer syntax with .scss extension.
  • Unlike Sass, SCSS has curly braces and semicolons, just like CSS.
  • Contrary to SCSS, Sass is difficult to read as it is quite deviant from CSS. Which is why SCSS it the more recommended Sass syntax as it is easier to read and closely resembles Native CSS while at the same time enjoying with power of Sass.

Consider the example below with Sass vs SCSS syntax along with Compiled CSS code.

    $font-color: #fff
    $bg-color: #00f

      color: $font-color
      background: $bg-color

    $font-color: #fff;
    $bg-color: #00f;

      color: $font-color;
      background: $bg-color;

In both cases, be it Sass or SCSS, the compiled CSS code will be the same –

#box {
      color: #fff;
      background: #00f;

Usage of Sass

Arguably the most Popular front end framework Bootstrap is written in Sass. Up until version 3, Bootstrap was written in LESS but bootstrap 4 adopted Sass and boosted its popularity. A few of the big companies using Sass are – Zapier, Uber, Airbnb and Kickstarter.

LESS – Leaner Style Sheets

LESS is an acronym for “Leaner Stylesheets”. It was released in 2009 by Alexis Sellier, 3 years after the initial launch of Sass in 2006. While Sass is written in Ruby, LESS is written JavaScript. In fact, LESS is a JavaScript library that extends the functionality of native vanilla CSS with mixins, variables, nesting and rule set loop. Sass vs LESS has been a heated debate. It is no surprise that LESS is the strongest competitor to Sass and has the second-largest user base. However, When bootstrap dumped LESS in favor of Sass with the launch of Bootstrap 4, LESS has waned in popularity. One of the few disadvantages of LESS over Sass is that it does not support functions. Unlike Sass, LESS uses @ to declare variables which might cause confusion with @media and @keyframes. However, One key advantage of LESS over Sass and Stylus or any other preprocessors, is the ease of adding it in your project. You can do that either by using NPM or by incorporating Less.js file. Syntax Declaration: LESS Uses .less extension. Syntax of LESS is quite similar to SCSS with the exception that for declaring variables, instead of $ sign, LESS uses @.

@font-color: #fff;
    @bg-color: #00f

      color: @font-color;
      background: @bg-color;

    #box {
        color: #fff;
        background: #00f;

Usage Of LESS The popular Bootstrap framework until the launch of version 4 was written in LESS. However, another popular framework called SEMANTIC UI is still written in LESS. Among the big companies using Sass are – Indiegogo, Patreon, and WeChat


The stylus was launched in 2010 by former Node JS developer TJ Holowaychuk, nearly 4 years after the release of Sass and 1 year after the release of LESS. The stylus is written Node JS and fits perfectly with JS stack. The stylus was heavily influenced by the logical prowess of the Sass and simplicity of LESS. Even though Stylus is still popular with Node JS developers, it hasn’t managed to carve out a sizeable share for itself. One advantage of Stylus over Sass or LESS, is that it is armed with extremely powerful built-in functions and is capable of handling heavy computing.

Syntax Declaration: Stylus Uses .styl extension. Stylus offers a great deal of flexibility in writing syntax, supports native CSS as well as allows omission of brackets colons and semicolons. Also, note that Stylus does not use @ or $ symbols for defining variables. Instead, Stylus uses the assignment operators to indicate a variable declaration.


font-color = #fff;
bg-color = #00f;

#box {
    color: font-color;
    background: bg-color;



font-color = #fff;
bg-color = #00f;

    color: font-color;
    background: bg-color;



font-color = #fff
bg-color = #00f

    color font-color
    background bg-color

How can I center a div within another div?

Make the CSS content this way...

#main_content {
    top: 160px;
    left: 160px;
    width: auto;
    min-height: 500px;
    height: auto;
    background-color: #2185C5;
    position: relative;

#container {
    height: auto;
    width: 90%;
    margin: 0 auto;
    background-color: #FFF;
    padding: 10px;

A working example is here:

How to add data validation to a cell using VBA

Use this one:

Dim ws As Worksheet
Dim range1 As Range, rng As Range
'change Sheet1 to suit
Set ws = ThisWorkbook.Worksheets("Sheet1")

Set range1 = ws.Range("A1:A5")
Set rng = ws.Range("B1")

With rng.Validation
    .Delete 'delete previous validation
    .Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, _
        Formula1:="='" & ws.Name & "'!" & range1.Address
End With

Note that when you're using Dim range1, rng As range, only rng has type of Range, but range1 is Variant. That's why I'm using Dim range1 As Range, rng As Range.
About meaning of parameters you can read is MSDN, but in short:

  • Type:=xlValidateList means validation type, in that case you should select value from list
  • AlertStyle:=xlValidAlertStop specifies the icon used in message boxes displayed during validation. If user enters any value out of list, he/she would get error message.
  • in your original code, Operator:= xlBetween is odd. It can be used only if two formulas are provided for validation.
  • Formula1:="='" & ws.Name & "'!" & range1.Address for list data validation provides address of list with values (in format =Sheet!A1:A5)

Get index of current item in a PowerShell loop

.NET has some handy utility methods for this sort of thing in System.Array:

PS> $a = 'a','b','c'
PS> [array]::IndexOf($a, 'b')
PS> [array]::IndexOf($a, 'c')

Good points on the above approach in the comments. Besides "just" finding an index of an item in an array, given the context of the problem, this is probably more suitable:

$letters = { 'A', 'B', 'C' }
$letters | % {$i=0} {"Value:$_ Index:$i"; $i++}

Foreach (%) can have a Begin sciptblock that executes once. We set an index variable there and then we can reference it in the process scripblock where it gets incremented before exiting the scriptblock.

Found shared references to a collection org.hibernate.HibernateException

I had the same problem. In my case, the issue was that someone used BeanUtils to copy the properties of one entity to another, so we ended up having two entities referencing the same collection.

Given that I spent some time investigating this issue, I would recommend the following checklist:

  • Look for scenarios like entity1.setCollection(entity2.getCollection()) and getCollection returns the internal reference to the collection (if getCollection() returns a new instance of the collection, then you don't need to worry).

  • Look if clone() has been implemented correctly.

  • Look for BeanUtils.copyProperties(entity1, entity2).

Iterating through all the cells in Excel VBA or VSTO 2005

My VBA skills are a little rusty, but this is the general idea of what I'd do.
The easiest way to do this would be to iterate through a loop for every column:

public sub CellProcessing()
on error goto errHandler

    dim MAX_ROW as Integer   'how many rows in the spreadsheet
    dim i as Integer
    dim cols as String

    for i = 1 to MAX_ROW
        'perform checks on the cell here
        'access the cell with Range("A" & i) to get cell A1 where i = 1
    next i

    exit sub
    msgbox "Error " & err.Number & ": " & err.Description
    resume exitHandler
end sub

it seems that the color syntax highlighting doesn't like vba, but hopefully this will help somewhat (at least give you a starting point to work from).

  • Brisketeer

Fastest way to count exact number of rows in a very large table?

Not exactly a DBMS-agnostic solution, but at least your client code won't see the difference...

Create another table T with just one row and one integer field N1, and create INSERT TRIGGER that just executes:


Also create a DELETE TRIGGER that executes:


A DBMS worth its salt will guarantee the atomicity of the operations above2, and N will contain the accurate count of rows at all times, which is then super-quick to get by simply:


While triggers are DBMS-specific, selecting from T isn't and your client code won't need to change for each supported DBMS.

However, this can have some scalability issues if the table is INSERT or DELETE-intensive, especially if you don't COMMIT immediately after INSERT/DELETE.

1 These names are just placeholders - use something more meaningful in production.

2 I.e. N cannot be changed by a concurrent transaction between reading and writing to N, as long as both reading and writing are done in a single SQL statement.

How to get 2 digit year w/ Javascript?

The specific answer to this question is found in this one line below:

//pull the last two digits of the year_x000D_
//logs to console_x000D_
//creates a new date object (has the current date and time by default)_x000D_
//gets the full year from the date object (currently 2017)_x000D_
//converts the variable to a string_x000D_
//gets the substring backwards by 2 characters (last two characters)    _x000D_
console.log(new Date().getFullYear().toString().substr(-2));

Formatting Full Date Time Example (MMddyy): jsFiddle


//A function for formatting a date to MMddyy_x000D_
function formatDate(d)_x000D_
    //get the month_x000D_
    var month = d.getMonth();_x000D_
    //get the day_x000D_
    //convert day to string_x000D_
    var day = d.getDate().toString();_x000D_
    //get the year_x000D_
    var year = d.getFullYear();_x000D_
    //pull the last two digits of the year_x000D_
    year = year.toString().substr(-2);_x000D_
    //increment month by 1 since it is 0 indexed_x000D_
    //converts month to a string_x000D_
    month = (month + 1).toString();_x000D_
    //if month is 1-9 pad right with a 0 for two digits_x000D_
    if (month.length === 1)_x000D_
        month = "0" + month;_x000D_
    //if day is between 1-9 pad right with a 0 for two digits_x000D_
    if (day.length === 1)_x000D_
        day = "0" + day;_x000D_
    //return the string "MMddyy"_x000D_
    return month + day + year;_x000D_
var d = new Date();_x000D_

how to get the last character of a string?

You can use this simple ES6 method

const lastChar = (str) => str.split('').reverse().join(',').replace(',', '')[str.length === str.length + 1 ? 1 : 0];_x000D_
// example_x000D_

This will work in every browsers.

What is the height of Navigation Bar in iOS 7?

There is a difference between the navigation bar and the status bar. The confusing part is that it looks like one solid feature at the top of the screen, but the areas can actually be separated into two distinct views; a status bar and a navigation bar. The status bar spans from y=0 to y=20 points and the navigation bar spans from y=20 to y=64 points. So the navigation bar (which is where the page title and navigation buttons go) has a height of 44 points, but the status bar and navigation bar together have a total height of 64 points.

Here is a great resource that addresses this question along with a number of other sizing idiosyncrasies in iOS7:

jQuery append text inside of an existing paragraph tag

If you want to append text or html to span then you can do it as below.

$('p span#add_here').append('text goes here');

append will add text to span tag at the end.

to replace entire text or html inside of span you can use .text() or .html()

How do I read the source code of shell commands?

You can have it on github using the command

git clone

You can find all the source codes in the src folder.

You need to have git installed.

Things have changed since 2012, ls source code has now 5309 lines

Creating new database from a backup of another Database on the same server?

Think of it like an archive. MyDB.Bak contains MyDB.mdf and MyDB.ldf.

Restore with Move to say HerDB basically grabs MyDB.mdf (and ldf) from the back up, and copies them as HerDB.mdf and ldf.

So if you already had a MyDb on the server instance you are restoring to it wouldn't be touched.

Can’t delete docker image with dependent child images

I also got this issue, I could resolve issue with below commands. this may be cause, the image's container is running or exit so before remove image you need to remove container

docker ps -a -f status=exited : this command shows all the exited containers so then copy container Id and then run below commands to remove container

docker rm #containerId : this command remove container this may be issue that mention "image has dependent child images"

Then try to remove image with below command

docker rmi #ImageId

Dictionary of dictionaries in Python?

Using collections.defaultdict is a big time-saver when you're building dicts and don't know beforehand which keys you're going to have.

Here it's used twice: for the resulting dict, and for each of the values in the dict.

import collections

def aggregate_names(errors):
    result = collections.defaultdict(lambda: collections.defaultdict(list))
    for real_name, false_name, location in errors:
    return result

Combining this with your code:

dictionary = aggregate_names(previousFunction(string))

Or to test:

    ('Fred', 'Frad', 123),
    ('Jim', 'Jam', 100),
    ('Fred', 'Frod', 200),
    ('Fred', 'Frad', 300)]
print aggregate_names(EXAMPLES)

#pragma mark in Swift?

Apple states in the latest version of Building Cocoa Apps,

The Swift compiler does not include a preprocessor. Instead, it takes advantage of compile-time attributes, build configurations, and language features to accomplish the same functionality. For this reason, preprocessor directives are not imported in Swift.

The # character appears to still be how you work with various build configurations and things like that, but it looks like they're trying to cut back on your need for most preprocessing in the vein of pragma and forward you to other language features altogether. Perhaps this is to aid in the operation of the Playgrounds and the REPL behaving as close as possible to the fully compiled code.

Cannot refer to a non-final variable inside an inner class defined in a different method

One solution I have noticed isn't mentioned (unless I missed it, if I did please correct me), is the use of a class variable. Ran into this issue attempting to run a new thread within a method: new Thread(){ Do Something }.

Calling doSomething() from the following will work. You do not necessarily have to declare it final, just need to change the scope of the variable so it is not collected before the innerclass. This is unless of course your process is huge and changing the scope might create some sort of conflict. I didn't want to make my variable final as it was in no way a final/constant.

public class Test

    protected String var1;
    protected String var2;

    public void doSomething()
        new Thread()
            public void run()
                System.out.println("In Thread variable 1: " + var1);
                System.out.println("In Thread variable 2: " + var2);


"A referral was returned from the server" exception when accessing AD from C#

In my case I was seeing referrals when I was accessing AD via SSO with an account in a trusted domain. The problem went away when I connected with explicit credentials in the local domain.

i.e. I replaced

DirectoryEntry de = new DirectoryEntry("");


DirectoryEntry de = new DirectoryEntry("", "[email protected]", "supersecret");

and the problem went away.

How can I add a space in between two outputs?


class Main
    public static void main(String[] args)  
        int a=10, b=20;
        System.out.println(a + " " + b);

Input: none

Output: 10 20

How to give a pandas/matplotlib bar graph custom colors

You can specify the color option as a list directly to the plot function.

from matplotlib import pyplot as plt
from itertools import cycle, islice
import pandas, numpy as np  # I find np.random.randint to be better

# Make the data
x = [{i:np.random.randint(1,5)} for i in range(10)]
df = pandas.DataFrame(x)

# Make a list by cycling through the colors you care about
# to match the length of your data.
my_colors = list(islice(cycle(['b', 'r', 'g', 'y', 'k']), None, len(df)))

# Specify this list of colors as the `color` option to `plot`.
df.plot(kind='bar', stacked=True, color=my_colors)

To define your own custom list, you can do a few of the following, or just look up the Matplotlib techniques for defining a color item by its RGB values, etc. You can get as complicated as you want with this.

my_colors = ['g', 'b']*5 # <-- this concatenates the list to itself 5 times.
my_colors = [(0.5,0.4,0.5), (0.75, 0.75, 0.25)]*5 # <-- make two custom RGBs and repeat/alternate them over all the bar elements.
my_colors = [(x/10.0, x/20.0, 0.75) for x in range(len(df))] # <-- Quick gradient example along the Red/Green dimensions.

The last example yields the follow simple gradient of colors for me:

enter image description here

I didn't play with it long enough to figure out how to force the legend to pick up the defined colors, but I'm sure you can do it.

In general, though, a big piece of advice is to just use the functions from Matplotlib directly. Calling them from Pandas is OK, but I find you get better options and performance calling them straight from Matplotlib.

Parse string to DateTime in C#

The simple and straightforward answer -->

using System;

namespace DemoApp.App

public class TestClassDate
    public static DateTime GetDate(string string_date)
        DateTime dateValue;
        if (DateTime.TryParse(string_date, out dateValue))
            Console.WriteLine("Converted '{0}' to {1}.", string_date, dateValue);
            Console.WriteLine("Unable to convert '{0}' to a date.", string_date);
        return dateValue;
    public static void Main()
        string inString = "05/01/2009 06:32:00";

 * Output:
 * Converted '05/01/2009 06:32:00' to 5/1/2009 6:32:00 AM.
 * */

Creating a Jenkins environment variable using Groovy

For me the following worked on Jenkins 2.190.1 and was much simpler than some of the other workarounds:

matcher = manager.getLogMatcher('^.*Text we want comes next: (.*)$');

if (matcher.matches()) {
    def myVar =;
    def envVar = new EnvVars([MY_ENV_VAR: myVar]);
    def newEnv = Environment.create(envVar);, newEnv);
    // now the matched text from the LogMatcher is passed to an
    // env var we can access at $MY_ENV_VAR in post build steps

This was using the Groovy Script plugin with no additional changes to Jenkins.

How to install PyQt4 on Windows using pip?

QT no longer supports PyQt4, but you can install PyQt5 with pip:

pip install PyQt5

How to check if a string is a valid JSON string in JavaScript without using Try/Catch

I know i'm 3 years late to this question, but I felt like chiming in.

While Gumbo's solution works great, it doesn't handle a few cases where no exception is raised for JSON.parse({something that isn't JSON})

I also prefer to return the parsed JSON at the same time, so the calling code doesn't have to call JSON.parse(jsonString) a second time.

This seems to work well for my needs:

function tryParseJSON (jsonString){
    try {
        var o = JSON.parse(jsonString);

        // Handle non-exception-throwing cases:
        // Neither JSON.parse(false) or JSON.parse(1234) throw errors, hence the type-checking,
        // but... JSON.parse(null) returns null, and typeof null === "object", 
        // so we must check for that, too. Thankfully, null is falsey, so this suffices:
        if (o && typeof o === "object") {
            return o;
    catch (e) { }

    return false;

Webdriver and proxy server for firefox

Look at the documentation page.

Tweaking an existing Firefox profile

You need to change "network.proxy.http" & "network.proxy.http_port" profile settings.

FirefoxProfile profile = new FirefoxProfile();
profile.addAdditionalPreference("network.proxy.http", "localhost");
profile.addAdditionalPreference("network.proxy.http_port", "3128");
WebDriver driver = new FirefoxDriver(profile);

Add a common Legend for combined ggplots

You may also use ggarrange from ggpubr package and set "common.legend = TRUE":


dsamp <- diamonds[sample(nrow(diamonds), 1000), ]
p1 <- qplot(carat, price, data = dsamp, colour = clarity)
p2 <- qplot(cut, price, data = dsamp, colour = clarity)
p3 <- qplot(color, price, data = dsamp, colour = clarity)
p4 <- qplot(depth, price, data = dsamp, colour = clarity) 

ggarrange(p1, p2, p3, p4, ncol=2, nrow=2, common.legend = TRUE, legend="bottom")

enter image description here

Spring Security with roles and permissions

To implement that, it seems that you have to:

  1. Create your model (user, role, permissions) and a way to retrieve permissions for a given user;
  2. Define your own and configure it (set its providers) to a custom This last one should return on its authenticate method a Authentication, which should be setted with the, in your case, all the permissions for the given user.

The trick in that article is to have roles assigned to users, but, to set the permissions for those roles in the Authentication.authorities object.

For that I advise you to read the API, and see if you can extend some basic ProviderManager and AuthenticationProvider instead of implementing everything. I've done that with setting a custom LdapAuthoritiesPopulator, that would retrieve the correct roles for the user.

Hope this time I got what you are looking for. Good luck.

Limit String Length

Do a little homework with the php online manual's string functions. You'll want to use strlen in a comparison setting, substr to cut it if you need to, and the concatenation operator with "..." or "&hellip;"