Programs & Examples On #Github api

An API used to retrieve information about data on GitHub.

Use Invoke-WebRequest with a username and password for basic authentication on the GitHub API

I am assuming Basic authentication here.

$cred = Get-Credential
Invoke-WebRequest -Uri 'https://whatever' -Credential $cred

You can get your credential through other means (Import-Clixml, etc.), but it does have to be a [PSCredential] object.

Edit based on comments:

GitHub is breaking RFC as they explain in the link you provided:

The API supports Basic Authentication as defined in RFC2617 with a few slight differences. The main difference is that the RFC requires unauthenticated requests to be answered with 401 Unauthorized responses. In many places, this would disclose the existence of user data. Instead, the GitHub API responds with 404 Not Found. This may cause problems for HTTP libraries that assume a 401 Unauthorized response. The solution is to manually craft the Authorization header.

Powershell's Invoke-WebRequest does to my knowledge wait for a 401 response before sending the credentials, and since GitHub never provides one, your credentials will never be sent.

Manually build the headers

Instead you'll have to create the basic auth headers yourself.

Basic authentication takes a string that consists of the username and password separated by a colon user:pass and then sends the Base64 encoded result of that.

Code like this should work:

$user = 'user'
$pass = 'pass'

$pair = "$($user):$($pass)"

$encodedCreds = [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes($pair))

$basicAuthValue = "Basic $encodedCreds"

$Headers = @{
    Authorization = $basicAuthValue

Invoke-WebRequest -Uri 'https://whatever' -Headers $Headers

You could combine some of the string concatenation but I wanted to break it out to make it clearer.

How can I see the size of a GitHub repository before cloning it?

To do this with curl (sudo apt-get curl) and json pretty (sudo gem install jsonpretty json):


Replace YOURGITHUBUSERNAME with your GitHub username (go figure).

Replace OWNER with the repository owner's Git username. Replace REPOSITORY with the repository name.

Or as a nice Bash script (paste this in a file named gitrepo-info):

if [ $# -ne 3 ]
  echo "Usage: gitrepo-info <username> <owner> <repo>"
  exit 65
curl -u "$1"$2/$3|jsonpretty

Use it like so:

gitrepo-info larowlan pisi reel

This will give me information on the pisi/reel repository on GitHub.

Git cli: get user info from username

git config --list

git config -l

will display your username and email together, along with other info

What are metaclasses in Python?

The type() function can return the type of an object or create a new type,

for example, we can create a Hi class with the type() function and do not need to use this way with class Hi(object):

def func(self, name='mike'):
    print('Hi, %s.' % name)

Hi = type('Hi', (object,), dict(hi=func))
h = Hi()
Hi, mike.



In addition to using type() to create classes dynamically, you can control creation behavior of class and use metaclass.

According to the Python object model, the class is the object, so the class must be an instance of another certain class. By default, a Python class is instance of the type class. That is, type is metaclass of most of the built-in classes and metaclass of user-defined classes.

class ListMetaclass(type):
    def __new__(cls, name, bases, attrs):
        attrs['add'] = lambda self, value: self.append(value)
        return type.__new__(cls, name, bases, attrs)

class CustomList(list, metaclass=ListMetaclass):

lst = CustomList()

['custom_list_1', 'custom_list_2']

Magic will take effect when we passed keyword arguments in metaclass, it indicates the Python interpreter to create the CustomList through ListMetaclass. new (), at this point, we can modify the class definition, for example, and add a new method and then return the revised definition.

What HTTP status response code should I use if the request is missing a required parameter?

I'm not sure there's a set standard, but I would have used 400 Bad Request, which the latest HTTP spec (from 2014) documents as follows:

6.5.1. 400 Bad Request

The 400 (Bad Request) status code indicates that the server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).

jQuery UI autocomplete with JSON

I use this script for autocomplete...

    source: function (request, response) {

        // $.getJSON("<?php echo base_url('index.php/Json_cr_operation/autosearch_custmoers');?>", function (data) {
          $.getJSON("Json_cr_operation/autosearch_custmoers?term=" + request.term, function (data) {
            response($.map(data, function (value, key) {
                return {
                    label: value.label,
                    value: value.value
    minLength: 1,
    delay: 100

My json return :- [{"label":"Mahesh Arun Wani","value":"1"}] after search m

but it display in dropdown [object object]...

PHP - find entry by object property from an array of objects

I solved this problem by keying the array with the ID. It's simpler and possibly faster for this scenario where the ID is what you're looking for.

[420] => stdClass Object
            [name] => Mary

[10957] => stdClass Object
            [name] => Blah

Now I can directly address the array:

$array[$v]->name = ...

Or, if I want to verify the existence of an ID:

if (array_key_exists($v, $array)) { ...

What is the difference between decodeURIComponent and decodeURI?

decodeURIComponent will decode URI special markers such as &, ?, #, etc, decodeURI will not.

Get list from pandas DataFrame column headers

>>> list(my_dataframe)
['y', 'gdp', 'cap']

To list the columns of a dataframe while in debugger mode, use a list comprehension:

>>> [c for c in my_dataframe]
['y', 'gdp', 'cap']

By the way, you can get a sorted list simply by using sorted:

>>> sorted(my_dataframe)
['cap', 'gdp', 'y']

How to read XML using XPath in Java

Here is an example of processing xpath with vtd-xml... for heavy duty XML processing it is second to none. here is the a recent paper on this subject Processing XML with Java – A Performance Benchmark

import com.ximpleware.*;

public class changeAttrVal {
    public  static  void main(String s[]) throws VTDException,,{
        VTDGen vg = new VTDGen();
        if (!vg.parseFile("input.xml", false))
        VTDNav vn = vg.getNav();
        AutoPilot ap = new AutoPilot(vn);
        XMLModifier xm = new XMLModifier(vn);
        ap.selectXPath("/*/place[@id=\"p14\" and   @initialMarking=\"2\"]/@initialMarking");
        int i=0;
            xm.updateToken(i+1, "499");// change initial marking from 2 to 499


error: member access into incomplete type : forward declaration of

Move doSomething definition outside of its class declaration and after B and also make add accessible to A by public-ing it or friend-ing it.

class B;

class A
    void doSomething(B * b);

class B
    void add() {}

void A::doSomething(B * b)

android listview get selected item

final ListView lv = (ListView) findViewById(;

lv.setOnItemClickListener(new OnItemClickListener() {
      public void onItemClick(AdapterView<?> myAdapter, View myView, int myItemInt, long mylng) {
        String selectedFromList =(String) (lv.getItemAtPosition(myItemInt));


I hope this fixes your problem.

How to get row number from selected rows in Oracle

you can just do

select rownum, l.* from student  l where name like %ram%

this assigns the row number as the rows are fetched (so no guaranteed ordering of course).

if you wanted to order first do:

select rownum, l.*
  from (select * from student l where name like %ram% order by...) l;

Unfortunately MyApp has stopped. How can I solve this?

People make mistakes, and so coding as well.

When ever any error happened, always check with the logcat with the text in red color however u can find out the real problem in blue color text with underline in those red color text.

Make sure if u create a new activity, always declare the activity in the AndroidManifest file.

If adding Permission, declare it in the AndroidMainifest file as well.

How to pass the id of an element that triggers an `onclick` event to the event handling function

<!DOCTYPE html>
<script src=""></script> 
<script type="text/javascript" src="jquery-2.1.0.js"></script> 
<script type="text/javascript" >
function openOnImageClick(event)
//alert("Jai Sh Raam");
// document.getElementById("images").src = "fruits.jpg";
var target = || event.srcElement; // IE

 var img = document.createElement('img');
 img.setAttribute('src', target.src);
  img.setAttribute('width', '200');
   img.setAttribute('height', '150');



<h1>Screen Shot View</h1>
<p>Click the Tiger to display the Image</p>

<div id="images" >

<img id="muID1" src="tiger.jpg" width="100" height="50" alt="unfinished bingo card" onclick="openOnImageClick(event)" />
<img id="myID2" src="sabaLogo1.jpg" width="100" height="50" alt="unfinished bingo card" onclick="openOnImageClick(event)" />


How to get the fields in an Object via reflection?

Here's a quick and dirty method that does what you want in a generic way. You'll need to add exception handling and you'll probably want to cache the BeanInfo types in a weakhashmap.

public Map<String, Object> getNonNullProperties(final Object thingy) {
    final Map<String, Object> nonNullProperties = new TreeMap<String, Object>();
    try {
        final BeanInfo beanInfo = Introspector.getBeanInfo(thingy
        for (final PropertyDescriptor descriptor : beanInfo
                .getPropertyDescriptors()) {
            try {
                final Object propertyValue = descriptor.getReadMethod()
                if (propertyValue != null) {
            } catch (final IllegalArgumentException e) {
                // handle this please
            } catch (final IllegalAccessException e) {
                // and this also
            } catch (final InvocationTargetException e) {
                // and this, too
    } catch (final IntrospectionException e) {
        // do something sensible here
    return nonNullProperties;

See these references:

Cannot enqueue Handshake after invoking quit

AWS Lambda functions

Use mysql.createPool() with connection.destroy()

This way, new invocations use the established pool, but don't keep the function running. Even though you don't get the full benefit of pooling (each new connection uses a new connection instead of an existing one), it makes it so that a second invocation can establish a new connection without the previous one having to be closed first.

Regarding connection.end()

This can cause a subsequent invocation to throw an error. The invocation will still retry later and work, but with a delay.

Regarding mysql.createPool() with connection.release()

The Lambda function will keep running until the scheduled timeout, as there is still an open connection.

Code example

const mysql = require('mysql');

const pool = mysql.createPool({
  connectionLimit: 100,
  host:     process.env.DATABASE_HOST,
  user:     process.env.DATABASE_USER,
  password: process.env.DATABASE_PASSWORD,

exports.handler = (event) => {
  pool.getConnection((error, connection) => {
    if (error) throw error;
      INSERT INTO table_name (event) VALUES ('${event}')
    `, function(error, results, fields) {
      if (error) throw error;

Playing HTML5 video on fullscreen in android webview

Cprcrack's answer works very well for API levels 19 and under. Just a minor addition to cprcrack's onShowCustomView will get it working on API level 21+

if (Build.VERSION.SDK_INT >= 21) {
      ((ViewGroup) webView.getParent()).addView(videoViewContainer);
      webView.scrollTo(0,0);  // centers full screen view 
} else {
      ViewGroup.LayoutParams vg = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,

You will also need to reflect the changes in onHideCustomView

Adding one day to a date

It Worked for me: For Current Date

$date = date('Y-m-d', strtotime("+1 day"));

for anydate:

date('Y-m-d', strtotime("+1 day", strtotime($date)));

What is the difference between new/delete and malloc/free?

new and delete are C++ primitives which declare a new instance of a class or delete it (thus invoking the destructor of the class for the instance).

malloc and free are C functions and they allocate and free memory blocks (in size).

Both use the heap to make the allocation. malloc and free are nonetheless more "low level" as they just reserve a chunk of memory space which will probably be associated with a pointer. No structures are created around that memory (unless you consider a C array to be a structure).

org.hibernate.MappingException: Unknown entity

use below line of code in the case of spring boot applications.


How to pass Multiple Parameters from ajax call to MVC Controller

  type: "POST",
  contentType: "application/json; charset=utf-8",
  url: "ChnagePassword.aspx/AutocompleteSuggestions",
  data: "{'searchstring':'" + request.term + "','st':'Arb'}",
  dataType: "json",
  success: function (data) {
     response($.map(data.d, function (item) {
         return { value: item }
  error: function (result) {

Android - Package Name convention

But if your Android App is only for personal purpose or created by you alone, you can use:

Access parent's parent from javascript object

If I'm reading your question correctly, objects in general are agnostic about where they are contained. They don't know who their parents are. To find that information, you have to parse the parent data structure. The DOM has ways of doing this for us when you're talking about element objects in a document, but it looks like you're talking about vanilla objects.

NSURLErrorDomain error codes description

I was unable to find name of an error for given code when developing in Swift. For that reason I paste minus codes for NSURLErrorDomain taken from NSURLError.h

    @enum NSURL-related Error Codes
    @abstract Constants used by NSError to indicate errors in the NSURL domain
    NSURLErrorUnknown =             -1,
    NSURLErrorCancelled =           -999,
    NSURLErrorBadURL =              -1000,
    NSURLErrorTimedOut =            -1001,
    NSURLErrorUnsupportedURL =          -1002,
    NSURLErrorCannotFindHost =          -1003,
    NSURLErrorCannotConnectToHost =         -1004,
    NSURLErrorNetworkConnectionLost =       -1005,
    NSURLErrorDNSLookupFailed =         -1006,
    NSURLErrorHTTPTooManyRedirects =        -1007,
    NSURLErrorResourceUnavailable =         -1008,
    NSURLErrorNotConnectedToInternet =      -1009,
    NSURLErrorRedirectToNonExistentLocation =   -1010,
    NSURLErrorBadServerResponse =       -1011,
    NSURLErrorUserCancelledAuthentication =     -1012,
    NSURLErrorUserAuthenticationRequired =  -1013,
    NSURLErrorZeroByteResource =        -1014,
    NSURLErrorCannotDecodeRawData =             -1015,
    NSURLErrorCannotDecodeContentData =         -1016,
    NSURLErrorCannotParseResponse =             -1017,
    NSURLErrorAppTransportSecurityRequiresSecureConnection NS_ENUM_AVAILABLE(10_11, 9_0) = -1022,
    NSURLErrorFileDoesNotExist =        -1100,
    NSURLErrorFileIsDirectory =         -1101,
    NSURLErrorNoPermissionsToReadFile =     -1102,
    NSURLErrorDataLengthExceedsMaximum NS_ENUM_AVAILABLE(10_5, 2_0) =   -1103,

    // SSL errors
    NSURLErrorSecureConnectionFailed =      -1200,
    NSURLErrorServerCertificateHasBadDate =     -1201,
    NSURLErrorServerCertificateUntrusted =  -1202,
    NSURLErrorServerCertificateHasUnknownRoot = -1203,
    NSURLErrorServerCertificateNotYetValid =    -1204,
    NSURLErrorClientCertificateRejected =   -1205,
    NSURLErrorClientCertificateRequired =   -1206,
    NSURLErrorCannotLoadFromNetwork =       -2000,

    // Download and file I/O errors
    NSURLErrorCannotCreateFile =        -3000,
    NSURLErrorCannotOpenFile =          -3001,
    NSURLErrorCannotCloseFile =         -3002,
    NSURLErrorCannotWriteToFile =       -3003,
    NSURLErrorCannotRemoveFile =        -3004,
    NSURLErrorCannotMoveFile =          -3005,
    NSURLErrorDownloadDecodingFailedMidStream = -3006,
    NSURLErrorDownloadDecodingFailedToComplete =-3007,

    NSURLErrorInternationalRoamingOff NS_ENUM_AVAILABLE(10_7, 3_0) =         -1018,
    NSURLErrorCallIsActive NS_ENUM_AVAILABLE(10_7, 3_0) =                    -1019,
    NSURLErrorDataNotAllowed NS_ENUM_AVAILABLE(10_7, 3_0) =                  -1020,
    NSURLErrorRequestBodyStreamExhausted NS_ENUM_AVAILABLE(10_7, 3_0) =      -1021,

    NSURLErrorBackgroundSessionRequiresSharedContainer NS_ENUM_AVAILABLE(10_10, 8_0) = -995,
    NSURLErrorBackgroundSessionInUseByAnotherProcess NS_ENUM_AVAILABLE(10_10, 8_0) = -996,
    NSURLErrorBackgroundSessionWasDisconnected NS_ENUM_AVAILABLE(10_10, 8_0)= -997,

Min and max value of input in angular4 application

You can control with a change event if the input is within your range, if it is not in the range you assign 0.

  <input type="number" 
    (change)= "rateInput < 0 ? rateInput = 0 : rateInput; rateInput > 100 ? rateInput = 0 : rateIntput;"
  <md-error>Required field</md-error>

How to center an unordered list?

To center align an unordered list, you need to use the CSS text align property. In addition to this, you also need to put the unordered list inside the div element.

Now, add the style to the div class and use the text-align property with center as its value.

See the below example.

.myDivElement ul li{

<div class="myDivElement">

Here is the reference website Center Align Unordered List

Vector of Vectors to create matrix

I did this class for that purpose. it produces a variable size matrix ( expandable) when more items are added


#pragma once
using namespace std;
template <class T>class Matrix
    Matrix() = default;
    bool AddItem(unsigned r, unsigned c, T value)
        if (r >= Rows_count)
            Rows.resize(r + 1);
            Rows_count = r + 1;
        if (c >= Columns_Count )
            for (std::vector<T>& row : Rows)
                row.resize(c + 1);
            Columns_Count = c + 1;
            for (std::vector<T>& row : Rows)
        if (r < Rows.size())
            if (c < static_cast<std::vector<T>>(
                ( = value;
                cout << << " greater than " << c << endl;
            cout << "ERROR" << endl;
        return true;
    void Show()
        std::cout << "*****************"<<std::endl;
        for (std::vector<T> r : Rows)
            for (auto& c : r)
                std::cout << " " <<setw(5)<< c;
            std::cout << std::endl;
        std::cout << "*****************" << std::endl;
    void Show(size_t n)
        std::cout << "*****************" << std::endl;
        for (std::vector<T> r : Rows)
            for (auto& c : r)
                std::cout << " " << setw(n) << c;
            std::cout << std::endl;
        std::cout << "*****************" << std::endl;
//  ~Matrix();
    std::vector<std::vector<T>> Rows;
    unsigned Rows_count;
    unsigned Columns_Count;


Get text of the selected option with jQuery

You could actually put the value = to the text and then do

        val = $j("#select_2 option:selected").html();

Or what I did on a similar case was

<select name="options[2]" id="select_2" onChange="JavascriptMethod()">
  with you're options here

With this second option you should have a undefined. Give me feedback if it worked :)


The application has stopped unexpectedly: How to Debug?

  1. From the Home screen, press the Menu key.
  2. List item
  3. Touch Settings.
  4. Touch Applications.
  5. Touch Manage Applications.
  6. Touch All.
  7. Select the application that is having issues.
  8. Touch Clear data and Clear cache if they are available. This resets the app as if it was new, and may delete personal data stored in the app.

Generics/templates in python?

Because Python is dynamically typed, the types of the objects don't matter in many cases. It's a better idea to accept anything.

To demonstrate what I mean, this tree class will accept anything for its two branches:

class BinaryTree:
    def __init__(self, left, right):
        self.left, self.right = left, right

And it could be used like this:

branch1 = BinaryTree(1,2)
myitem = MyClass()
branch2 = BinaryTree(myitem, None)
tree = BinaryTree(branch1, branch2)

How to access a mobile's camera from a web app?

Safari & Chrome on iOS 6+ and Android 2.2+ support HTML Media Capture which allows you to take pictures with your device's camera or select an existing one:

<input type="file" accept="image/*">

Here's how it works on iOS 10:

enter image description here

Android 3.0+ and Safari on iOS10.3+ also support the capture attribute which is used to jump straight to the camera.

<input type="file" accept="image/*" capture>

capture="camera" (String) and accept="image/*;capture=camera" (Parameter) were part of old specs and were replaced by capture (Boolean) the W3C Candidate Recommendation.

Support documentation: this 2013 O'Reilly book and my testing

How to create Custom Ratings bar in Android

You can have 5 imageview with defalut image as star that is empty and fill the rating bar with half or full image base on rating.

 public View getView(int position, View convertView, ViewGroup parent) {
     LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
     View grid=inflater.inflate(R.layout.griditem, parent, false);
     imgoff =(ImageView)grid.findViewById(;
     tv.setPadding(0, 2, 0, 0);
    Float rate=rateFArr[position];

   if(rate==5 || rate==4.5)
    if(rate==4 || rate==3.5)
    if(rate==3 || rate==2.5)
    if(rate==2 || rate==1.5)
    if(rate==1 || rate==0.5)


    // rb=(RatingBar)findViewById(;
        return grid;

Passing just a type as a parameter in C#

foo.GetColumnValues(dm.mainColumn, typeof(string))

Alternatively, you could use a generic method:

public void GetColumnValues<T>(object mainColumn)
    GetColumnValues(mainColumn, typeof(T));

and you could then use it like:


read.csv warning 'EOF within quoted string' prevents complete reading of file

I too had the similar problem. But in my case, the cause of the issue was due to the presence of apostrophes (i.e. single quotation marks) within some of the text values. This is especially frequent when working with data including texts in French, e.g. «L'autre jour».

So, the solution was simply to adjust the default setting of the quote argument to exclude the «'» symbol, and thus, using quote = "\"" (i.e. double quotation mark only), everything worked fine.

I hope that can help some of you. Cheers.

How do I read the first line of a file using cat?

I'm surprised that this question has been around as long as it has, and nobody has provided the pre-mapfile built-in approach yet.

IFS= read -r first_line <file

...puts the first line of the file in the variable expanded by "$first_line", easy as that.

Moreover, because read is built into bash and this usage requires no subshell, it's significantly more efficient than approaches involving subprocesses such as head or awk.

File Upload without Form

You can use FormData to submit your data by a POST request. Here is a simple example:

var myFormData = new FormData();
myFormData.append('pictureFile', pictureInput.files[0]);

  url: 'upload.php',
  type: 'POST',
  processData: false, // important
  contentType: false, // important
  dataType : 'json',
  data: myFormData

You don't have to use a form to make an ajax request, as long as you know your request setting (like url, method and parameters data).

"No such file or directory" but it exists

I had this issue and the reason was EOL in some editors such as Notepad++. You can check it in Edit menu/EOL conversion. Unix(LF) should be selected. I hope it would be useful.

How can I dynamically switch web service addresses in .NET without a recompile?

If you are fetching the URL from a database you can manually assign it to the web service proxy class URL property. This should be done before calling the web method.

If you would like to use the config file, you can set the proxy classes URL behavior to dynamic.

Using FFmpeg in .net?

GPL-compiled ffmpeg can be used from non-GPL program (commercial project) only if it is invoked in the separate process as command line utility; all wrappers that are linked with ffmpeg library (including Microsoft's FFMpegInterop) can use only LGPL build of ffmpeg.

You may try my .NET wrapper for FFMpeg: Video Converter for .NET (I'm an author of this library). It embeds FFMpeg.exe into the DLL for easy deployment and doesn't break GPL rules (FFMpeg is NOT linked and wrapper invokes it in the separate process with System.Diagnostics.Process).

Sorting arrays in NumPy by column

def sort_np_array(x, column=None, flip=False):
    x = x[np.argsort(x[:, column])]
    if flip:
        x = np.flip(x, axis=0)
    return x

Array in the original question:

a = np.array([[9, 2, 3],
              [4, 5, 6],
              [7, 0, 5]])

The result of the sort_np_array function as expected by the author of the question:

sort_np_array(a, column=1, flip=False)
[2]: array([[7, 0, 5],
            [9, 2, 3],
            [4, 5, 6]])

JavaScript dictionary with names

The main problem I see with what you have is that it's difficult to loop through, for populating a table.

Simply use an array of arrays:

var myMappings = [
    ["Name", "10%"], // Note the quotes around "10%"
    ["Phone", "10%"],
    // etc..

... which simplifies access:

myMappings[0][0]; // column name
myMappings[0][1]; // column width


var myMappings = {
    names: ["Name", "Phone", etc...],
    widths: ["10%", "10%", etc...]

And access with:


Delete specific line number(s) from a text file using sed?

If you want to delete lines 5 through 10 and 12:

sed -e '5,10d;12d' file

This will print the results to the screen. If you want to save the results to the same file:

sed -i.bak -e '5,10d;12d' file

This will back the file up to file.bak, and delete the given lines.

Note: Line numbers start at 1. The first line of the file is 1, not 0.

How to change package name of Android Project in Eclipse?

One extremely important notice:

NEVER use a direct package names as in something similar to passing a string value containing the package name. Use the method getPackageName(). This will make the renaming dynamic. Do whatever to reach the method getPackageName().

In Eclipse Juno, the correct way of renaming is:

  1. Go and edit the manifest.
  2. Remove every old package name in the manifest.
  3. Put instead of the old package name, the new package name in every location inside the manifest. You might have classes (Activities that is) that need direct package name references.
  4. Save the manifest.
  5. Then right click the package name inside the project.
  6. Select "Refactor".
  7. Select "Rename".
  8. Type the new package name.
  9. Select "update references".
  10. Press OK and you're done and watch out also what should be done to replace the new name.
  11. Don't forget to also update the layout XML files with the new package name. You might have a custom View. Look for them.

How to POST request using RestSharp

My RestSharp POST method:

var client = new RestClient(ServiceUrl);

var request = new RestRequest("/resource/", Method.POST);

// Json to post.
string jsonToSend = JsonHelper.ToJson(json);

request.AddParameter("application/json; charset=utf-8", jsonToSend, ParameterType.RequestBody);
request.RequestFormat = DataFormat.Json;

    client.ExecuteAsync(request, response =>
        if (response.StatusCode == HttpStatusCode.OK)
            // OK
            // NOK
catch (Exception error)
    // Log

Angular ng-click with call to a controller function not working

Use alias when defining Controller in your angular configuration. For example: NOTE: I'm using TypeScript here

Just take note of the Controller, it has an alias of homeCtrl.

module MongoAngular {
    var app = angular.module('mongoAngular', ['ngResource', 'ngRoute','restangular']);

        '$routeProvider', ($routeProvider: ng.route.IRouteProvider) => {
                .when('/Home', {
                    templateUrl: '/PartialViews/Home/home.html',
                    controller: 'HomeController as homeCtrl'
                .otherwise({ redirectTo: '/Home' });
        .config(['RestangularProvider', (restangularProvider: restangular.IProvider) => {

And here's the way to use it...


Try it.. It might work for you as it worked for me... ;)

get current date with 'yyyy-MM-dd' format in Angular 4

If you only want to display then you can use date pipe in HTML like this :

Just Date:

your date | date: 'dd MMM yyyy'

Date With Time:

your date | date: 'dd MMM yyyy hh:mm a'

And if you want to take input only date from new Date() then :

You can use angular formatDate() in ts file like this -

currentDate = new Date();

const cValue = formatDate(currentDate, 'yyyy-MM-dd', 'en-US');

nullable object must have a value

Assign the members directly without the .Value part:

DateTimeExtended(DateTimeExtended myNewDT)
   this.MyDateTime = myNewDT.MyDateTime;
   this.otherdata = myNewDT.otherdata;

My docker container has no internet

Fixed by following this advice:

[...] can you try to reset everything?

pkill docker
iptables -t nat -F
ifconfig docker0 down
brctl delbr docker0
docker -d

It will force docker to recreate the bridge and reinit all the network rules

Seems the interface was 'hung' somehow.

Update for more recent versions of docker:

The above answer might still get the job done for you but it has been quite a long time since this answer was posted and docker is more polished now so make sure you try these first before going into mangling with iptables and all.

sudo service docker restart or (if you are in a linux distro that does not use upstart) sudo systemctl restart docker

TypeScript and field initializers

I'd be more inclined to do it this way, using (optionally) automatic properties and defaults. You haven't suggested that the two fields are part of a data structure, so that's why I chose this way.

You could have the properties on the class and then assign them the usual way. And obviously they may or may not be required, so that's something else too. It's just that this is such nice syntactic sugar.

class MyClass{
    constructor(public Field1:string = "", public Field2:string = "")
        // other constructor stuff

var myClass = new MyClass("ASD", "QWE");
alert(myClass.Field1); // voila! statement completion on these properties

How can JavaScript save to a local file?

It is not possible to save file locally without involving the local client (browser machine) as I could be a great threat to client machine. You can use link to download that file. If you want to store something like Json data on local machine you can use LocalStorage provided by the browsers, Web Storage

How to remove commits from a pull request

So do the following ,

Lets say your branch name is my_branch and this has the extra commits.

  1. git checkout -b my_branch_with_extra_commits (Keeping this branch saved under a different name)
  2. gitk (Opens git console)
  3. Look for the commit you want to keep. Copy the SHA of that commit to a notepad.
  4. git checkout my_branch
  5. gitk (This will open the git console )
  6. Right click on the commit you want to revert to (State before your changes) and click on "reset branch to here"
  7. Do a git pull --rebase origin branch_name_to _merge_to
  8. git cherry-pick <SHA you copied in step 3. >

Now look at the local branch commit history and make sure everything looks good.

Why can't Python parse this JSON data?

Here you go with modified data.json file:

    "maps": [
            "id": "blabla",
            "iscategorical": "0"
            "id": "blabla",
            "iscategorical": "0"
    "masks": [{
        "id": "valore"
    "om_points": "value",
    "parameters": [{
        "id": "valore"

You can call or print data on console by using below lines:

import json
from pprint import pprint
with open('data.json') as data_file:
    data_item = json.load(data_file)

Expected output for print(data_item['parameters'][0]['id']):

{'maps': [{'id': 'blabla', 'iscategorical': '0'},
          {'id': 'blabla', 'iscategorical': '0'}],
 'masks': [{'id': 'valore'}],
 'om_points': 'value',
 'parameters': [{'id': 'valore'}]}

Expected output for print(data_item['parameters'][0]['id']):


How do I get the path of a process in Unix / Linux

The below command search for the name of the process in the running process list,and redirect the pid to pwdx command to find the location of the process.

ps -ef | grep "abc" |grep -v grep| awk '{print $2}' | xargs pwdx

Replace "abc" with your specific pattern.

Alternatively, if you could configure it as a function in .bashrc, you may find in handy to use if you need this to be used frequently.

ps1() { ps -ef | grep "$1" |grep -v grep| awk '{print $2}' | xargs pwdx; }

For eg:

[admin@myserver:/home2/Avro/AvroGen]$ ps1 nifi

18404: /home2/Avro/NIFI

Hope this helps someone sometime.....

React proptype array with shape

This was my solution to protect against an empty array as well:

import React, { Component } from 'react';
import { arrayOf, shape, string, number } from 'prop-types';

ReactComponent.propTypes = {
  arrayWithShape: (props, propName, componentName) => {
    const arrayWithShape = props[propName]
    PropTypes.checkPropTypes({ arrayWithShape:
            color: string.isRequired,
            fontSize: number.isRequired,
    }, {arrayWithShape}, 'prop', componentName);
    if(arrayWithShape.length < 1){
      return new Error(`${propName} is empty`)

Highlight text similar to grep, but don't filter out text

If you want to print "all" lines, there is a simple working solution:

grep "test" -A 9999999 -B 9999999
  • A => After
  • B => Before

Javascript set img src

Pure JavaScript to Create img tag and add attributes manually ,

var image = document.createElement("img");
var imageParent = document.getElementById("body"); = "id";
image.className = "class";
image.src = searchPic.src;            // image.src = "IMAGE URL/PATH"

Set src in pic1

document["#pic1"].src = searchPic.src;

or with getElementById

document.getElementById("pic1").src= searchPic.src;

j-Query to archive this,

$("#pic1").attr("src", searchPic.src);

Adding POST parameters before submit

You can do a form.serializeArray(), then add name-value pairs before posting:

var form = $(this).closest('form');

form = form.serializeArray();

form = form.concat([
    {name: "customer_id", value: window.username},
    {name: "post_action", value: "Update Information"}

$.post('/change-user-details', form, function(d) {
    if (d.error) {
        alert("There was a problem updating your user details")

How to prevent Browser cache for php site

You can try this:

    header("Expires: Tue, 03 Jul 2001 06:00:00 GMT");
    header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
    header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
    header("Cache-Control: post-check=0, pre-check=0", false);
    header("Pragma: no-cache");
    header("Connection: close");

Hopefully it will help prevent Cache, if any!


bash -c works well if the commands you are running are relatively simple. However, if you're trying to run a long series of commands full of control characters, it can get complex.

I successfully got around this by piping my commands into the process from the outside, i.e.

cat | docker run -i <image> /bin/bash

AES Encrypt and Decrypt

This is a pretty old post but XCode 10 added the CommonCrypto module so you don't need a module map. Also with Swift 5, no need for the annoying casts.

You could do something like:

func decrypt(_ data: Data, iv: Data, key: Data) throws -> String {

    var buffer = [UInt8](repeating: 0, count: data.count + kCCBlockSizeAES128)
    var bufferLen: Int = 0

    let status = CCCrypt(

    guard status == kCCSuccess,
        let str = String(data: Data(bytes: buffer, count: bufferLen),
                         encoding: .utf8) else {
                            throw NSError(domain: "AES", code: -1, userInfo: nil)

    return str

Assigning variables with dynamic names in Java

You should use List or array instead

List<Integer> list = new ArrayList<Integer>();


int[] arr  = new int[10];

Or even better

Map<String, Integer> map = new HashMap<String, Integer>();
map.put("n1", 1);
map.put("n2", 2);

//conditionally get 

How to close form

Why not use the DialogResult method to close the form?

if(DialogSettingsCancel.ShowDialog() == DialogResult.Yes)
     //this will close the form but will keep application open if your 
     //application type is "console" in the properties of the project

For this to work however you will need to do it inside your "WindowSettings" form while you call the DialogSettingsCancel form. Much the same way you would call the OpenFileDialog, or any other Dialog form.

Why is the time complexity of both DFS and BFS O( V + E )

Short but simple explanation:

I the worst case you would need to visit all the vertex and edge hence the time complexity in the worst case is O(V+E)

Bootstrap 3 - How to load content in modal body via AJAX?

Check this SO answer out.

It looks like the only way is to provide the whole modal structure with your ajax response.

As you can check from the bootstrap source code, the load function is binded to the root element.

In case you can't modify the ajax response, a simple workaround could be an explicit call of the $(..).modal(..) plugin on your body element, even though it will probably break the show/hide functions of the root element.

Python Remove last 3 characters of a string

Aren't you performing the operations in the wrong order? You requirement seems to be foo[:-3].replace(" ", "").upper()

Javascript array declaration: new Array(), new Array(3), ['a', 'b', 'c'] create arrays that behave differently

Arrays have numerical indexes. So,

a = new Array();


b = new Array(2);

are not adding elements to the array, but adding .a1 and .a2 properties to the a object (arrays are objects too). As further evidence, if you did this:

a = new Array();
console.log(a.length);   // outputs zero because there are no items in the array

Your third option:


is assigning the variable c an array with three elements. Those three elements can be accessed as: c[0], c[1] and c[2]. In other words, c[0] === 'c1' and c.length === 3.

Javascript does not use its array functionality for what other languages call associative arrays where you can use any type of key in the array. You can implement most of the functionality of an associative array by just using an object in javascript where each item is just a property like this.

a = {};

It is generally a mistake to use an array for this purpose as it just confuses people reading your code and leads to false assumptions about how the code works.

How to read first N lines of a file?

Based on gnibbler top voted answer (Nov 20 '09 at 0:27): this class add head() and tail() method to file object.

class File(file):
    def head(self, lines_2find=1):                            #Rewind file
        return [ for x in xrange(lines_2find)]

    def tail(self, lines_2find=1): , 2)                         #go to end of file
        bytes_in_file = self.tell()             
        lines_found, total_bytes_scanned = 0, 0
        while (lines_2find+1 > lines_found and
               bytes_in_file > total_bytes_scanned): 
            byte_block = min(1024, bytes_in_file-total_bytes_scanned)
  , 2)
            total_bytes_scanned += byte_block
            lines_found +='\n'), 2)
        line_list = list(self.readlines())
        return line_list[-lines_2find:]


f = File('path/to/file', 'r')

copy db file with adb pull results in 'permission denied' error

This generic solution should work on all rooted devices:

 adb shell "su -c cat /data/data/" > contacts2.d

The command connects as shell, then executes cat as root and collects the output into a local file.

In opposite to @guest-418 s solution, one does not have to dig for the user in question.

Plus If you get greedy and want all the db's at once (eg. for backup)

for i in `adb shell "su -c find /data -name '*.db'"`; do
    mkdir -p ".`dirname $i`"
    adb shell "su -c cat $i" > ".$i" 

This adds a mysteryous question mark to the end of the filename, but it is still readable.

Android: resizing imageview in XML

Please try this one works for me:

<ImageView android:id="@+id/image_view"     

What is the difference between using constructor vs getInitialState in React / React Native?

OK, the big difference is start from where they are coming from, so constructor is the constructor of your class in JavaScript, on the other side, getInitialState is part of the lifecycle of React.

constructor is where your class get initialised...


The constructor method is a special method for creating and initializing an object created with a class. There can only be one special method with the name "constructor" in a class. A SyntaxError will be thrown if the class contains more than one occurrence of a constructor method.

A constructor can use the super keyword to call the constructor of a parent class.

In the React v16 document, they didn't mentioned any preference, but you need to getInitialState if you using createReactClass()...

Setting the Initial State

In ES6 classes, you can define the initial state by assigning this.state in the constructor:

class Counter extends React.Component {
  constructor(props) {
    this.state = {count: props.initialCount};
  // ...

With createReactClass(), you have to provide a separate getInitialState method that returns the initial state:

var Counter = createReactClass({
  getInitialState: function() {
    return {count: this.props.initialCount};
  // ...

Visit here for more information.

Also created the image below to show few lifecycles of React Compoenents:

React lifecycle

The meaning of NoInitialContextException error

My problem with this one was that I was creating a hibernate session, but had the JNDI settings for my database instance wrong because of a classpath problem. Just FYI...

Split List into Sublists with LINQ

It's an old solution but I had a different approach. I use Skip to move to desired offset and Take to extract desired number of elements:

public static IEnumerable<IEnumerable<T>> Chunk<T>(this IEnumerable<T> source, 
                                                   int chunkSize)
    if (chunkSize <= 0)
        throw new ArgumentOutOfRangeException($"{nameof(chunkSize)} should be > 0");

    var nbChunks = (int)Math.Ceiling((double)source.Count()/chunkSize);

    return Enumerable.Range(0, nbChunks)
                     .Select(chunkNb => source.Skip(chunkNb*chunkSize)

One line if/else condition in linux shell scripting

It's not a direct answer to the question but you could just use the OR-operator

( grep "#SystemMaxUse=" journald.conf > /dev/null && sed -i 's/\#SystemMaxUse=/SystemMaxUse=50M/g' journald.conf ) || echo "This file has been edited. You'll need to do it manually."

Change User Agent in UIWebView

The only problem I have found was change user agent only

- (BOOL)application:(UIApplication *)application
        didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    NSDictionary *dictionary = [NSDictionary 
        @"Mozilla/5.0 (iPod; U; CPU iPhone OS 4_3_3 like Mac OS X; ja-jp) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5", 
        @"UserAgent", nil];
    [[NSUserDefaults standardUserDefaults] registerDefaults:dictionary];

Javascript: How to pass a function with string parameters as a parameter to another function

Try this:


Then you just need to call these two functions passed to myfunction:

function myfunction(url, f1, f2) {
    // …

How to refresh the data in a jqGrid?

var newdata= //You call Ajax peticion//


$("#idGrid").jqGrid('setGridParam', {data:newdata)});

in event update data table

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?

Extract only right most n letters from a string

//s - your string
//n - maximum number of right characters to take at the end of string
(new Regex("^.*?(.{1,n})$")).Replace(s,"$1")

SQL query to find record with ID not in another table


FROM    table1 a
            LEFT JOIN table2 b
                on a.ID = b.ID

Stacked Tabs in Bootstrap 3

Left, Right and Below tabs were removed from Bootstrap 3, but you can add custom CSS to achieve this..

.tabs-below > .nav-tabs,
.tabs-right > .nav-tabs,
.tabs-left > .nav-tabs {
  border-bottom: 0;

.tab-content > .tab-pane,
.pill-content > .pill-pane {
  display: none;

.tab-content > .active,
.pill-content > .active {
  display: block;

.tabs-below > .nav-tabs {
  border-top: 1px solid #ddd;

.tabs-below > .nav-tabs > li {
  margin-top: -1px;
  margin-bottom: 0;

.tabs-below > .nav-tabs > li > a {
  -webkit-border-radius: 0 0 4px 4px;
     -moz-border-radius: 0 0 4px 4px;
          border-radius: 0 0 4px 4px;

.tabs-below > .nav-tabs > li > a:hover,
.tabs-below > .nav-tabs > li > a:focus {
  border-top-color: #ddd;
  border-bottom-color: transparent;

.tabs-below > .nav-tabs > .active > a,
.tabs-below > .nav-tabs > .active > a:hover,
.tabs-below > .nav-tabs > .active > a:focus {
  border-color: transparent #ddd #ddd #ddd;

.tabs-left > .nav-tabs > li,
.tabs-right > .nav-tabs > li {
  float: none;

.tabs-left > .nav-tabs > li > a,
.tabs-right > .nav-tabs > li > a {
  min-width: 74px;
  margin-right: 0;
  margin-bottom: 3px;

.tabs-left > .nav-tabs {
  float: left;
  margin-right: 19px;
  border-right: 1px solid #ddd;

.tabs-left > .nav-tabs > li > a {
  margin-right: -1px;
  -webkit-border-radius: 4px 0 0 4px;
     -moz-border-radius: 4px 0 0 4px;
          border-radius: 4px 0 0 4px;

.tabs-left > .nav-tabs > li > a:hover,
.tabs-left > .nav-tabs > li > a:focus {
  border-color: #eeeeee #dddddd #eeeeee #eeeeee;

.tabs-left > .nav-tabs .active > a,
.tabs-left > .nav-tabs .active > a:hover,
.tabs-left > .nav-tabs .active > a:focus {
  border-color: #ddd transparent #ddd #ddd;
  *border-right-color: #ffffff;

.tabs-right > .nav-tabs {
  float: right;
  margin-left: 19px;
  border-left: 1px solid #ddd;

.tabs-right > .nav-tabs > li > a {
  margin-left: -1px;
  -webkit-border-radius: 0 4px 4px 0;
     -moz-border-radius: 0 4px 4px 0;
          border-radius: 0 4px 4px 0;

.tabs-right > .nav-tabs > li > a:hover,
.tabs-right > .nav-tabs > li > a:focus {
  border-color: #eeeeee #eeeeee #eeeeee #dddddd;

.tabs-right > .nav-tabs .active > a,
.tabs-right > .nav-tabs .active > a:hover,
.tabs-right > .nav-tabs .active > a:focus {
  border-color: #ddd #ddd #ddd transparent;
  *border-left-color: #ffffff;

Working example:


If you don't need the exact look of a tab (bordered appropriately on the left or right as each tab is activated), you can simple use nav-stacked, along with Bootstrap col-* to float the tabs to the left or right...

nav-stacked demo:

<ul class="nav nav-pills nav-stacked col-md-3">
    <li><a href="#a" data-toggle="tab">1</a></li>
    <li><a href="#b" data-toggle="tab">2</a></li>
    <li><a href="#c" data-toggle="tab">3</a></li>

ASP.NET Core Web API Authentication

You can implement a middleware which handles Basic authentication.

public async Task Invoke(HttpContext context)
    var authHeader = context.Request.Headers.Get("Authorization");
    if (authHeader != null && authHeader.StartsWith("basic", StringComparison.OrdinalIgnoreCase))
        var token = authHeader.Substring("Basic ".Length).Trim();
        var credentialstring = Encoding.UTF8.GetString(Convert.FromBase64String(token));
        var credentials = credentialstring.Split(':');
        if(credentials[0] == "admin" && credentials[1] == "admin")
            var claims = new[] { new Claim("name", credentials[0]), new Claim(ClaimTypes.Role, "Admin") };
            var identity = new ClaimsIdentity(claims, "Basic");
            context.User = new ClaimsPrincipal(identity);
        context.Response.StatusCode = 401;
        context.Response.Headers.Set("WWW-Authenticate", "Basic realm=\"\"");
    await _next(context);

This code is written in a beta version of core. Hope it helps.

Java converting Image to BufferedImage

If you use Kotlin, you can add an extension method to Image in the same manner Sri Harsha Chilakapati suggests.

fun Image.toBufferedImage(): BufferedImage {
    if (this is BufferedImage) {
        return this
    val bufferedImage = BufferedImage(this.getWidth(null), this.getHeight(null), BufferedImage.TYPE_INT_ARGB)

    val graphics2D = bufferedImage.createGraphics()
    graphics2D.drawImage(this, 0, 0, null)

    return bufferedImage

And use it like this:


What’s the best way to get an HTTP response code from a URL?

Update using the wonderful requests library. Note we are using the HEAD request, which should happen more quickly then a full GET or POST request.

import requests
    r = requests.head("")
    # prints the int of the status code. Find more at :)
except requests.ConnectionError:
    print("failed to connect")

Read all worksheets in an Excel workbook into an R list with data.frames

Updated answer using readxl (22nd June 2015)

Since posting this question the readxl package has been released. It supports both xls and xlsx format. Importantly, in contrast to other excel import packages, it works on Windows, Mac, and Linux without requiring installation of additional software.

So a function for importing all sheets in an Excel workbook would be:

read_excel_allsheets <- function(filename, tibble = FALSE) {
    # I prefer straight data.frames
    # but if you like tidyverse tibbles (the default with read_excel)
    # then just pass tibble = TRUE
    sheets <- readxl::excel_sheets(filename)
    x <- lapply(sheets, function(X) readxl::read_excel(filename, sheet = X))
    if(!tibble) x <- lapply(x,
    names(x) <- sheets

This could be called with:

mysheets <- read_excel_allsheets("foo.xls")

Old Answer

Building on the answer provided by @mnel, here is a simple function that takes an Excel file as an argument and returns each sheet as a data.frame in a named list.


importWorksheets <- function(filename) {
    # filename: name of Excel file
    workbook <- loadWorkbook(filename)
    sheet_names <- getSheets(workbook)
    names(sheet_names) <- sheet_names
    sheet_list <- lapply(sheet_names, function(.sheet){
        readWorksheet(object=workbook, .sheet)})

Thus, it could be called with:


Check if application is installed - Android

protected void onResume() {
    boolean installed = false;

    while (!installed) {
        installed = appInstalledOrNot (APPPACKAGE);
        if (installed) {
            Toast.makeText(this, "App installed", Toast.LENGTH_SHORT).show ();

private boolean appInstalledOrNot (String uri) {
    PackageManager pm = getPackageManager();
    boolean app_installed = false;
    try {
        pm.getPackageInfo(uri, PackageManager.GET_ACTIVITIES);
        app_installed = true;
    } catch (PackageManager.NameNotFoundException e) {
        app_installed = false;
    return app_installed;

Equivalent of jQuery .hide() to set visibility: hidden

If you only need the standard functionality of hide only with visibility:hidden to keep the current layout you can use the callback function of hide to alter the css in the tag. Hide docs in jquery

An example :

$('#subs_selection_box').fadeOut('slow', function() {

This will use the normal cool animation to hide the div, but after the animation finish you set the visibility to hidden and display to block.

An example :

I know you didnt want the $("#aa").css() solution, but you did not specify if it was because using only the css() method you lose the animation.

Why do many examples use `fig, ax = plt.subplots()` in Matplotlib/pyplot/python

In addition to the answers above, you can check the type of object using type(plt.subplots()) which returns a tuple, on the other hand, type(plt.subplot()) returns matplotlib.axes._subplots.AxesSubplot which you can't unpack.

Calling a Javascript Function from Console

This is an older thread, but I just searched and found it. I am new to using Web Developer Tools: primarily Firefox Developer Tools (Firefox v.51), but also Chrome DevTools (Chrome v.56)].

I wasn't able to run functions from the Developer Tools console, but I then found this

and I was able to add code to the Scratchpad, highlight and run a function, outputted to console per the attched screenshot.

I also added the Chrome "Scratch JS" extension: it looks like it provides the same functionality as the Scratchpad in Firefox Developer Tools (screenshot below).

Image 1 (Firefox):

enter image description here

Image 2 (Chrome):

enter image description here

How to find out if you're using HTTPS without $_SERVER['HTTPS']

This is how i find solve this

$https = !empty($_SERVER['HTTPS']) && strcasecmp($_SERVER['HTTPS'], 'on') === 0 ||
        !empty($_SERVER['HTTP_X_FORWARDED_PROTO']) &&
            strcasecmp($_SERVER['HTTP_X_FORWARDED_PROTO'], 'https') === 0;

return ($https) ? 'https://' : 'http://';

python ValueError: invalid literal for float()

Watch out for possible unintended literals in your argument

for example you can have a space within your argument, rendering it to a string / literal:

float(' 0.33')

After making sure the unintended space did not make it into the argument, I was left with:


Like this it works like a charm.

Take away is: Pay Attention for unintended literals (e.g. spaces that you didn't see) within your input.

Why do I get "'property cannot be assigned" when sending an SMTP email?

Initialize the MailMessage with sender and reciever's email addresses. It should be something like

string from = "[email protected]";  //Senders email   
string to = "[email protected]";  //Receiver's email  
MailMessage msg = new MailMessage(from, to); 

Read the full code snippet of how to send emails in c#

Command to run a .bat file

Can refer to here:

start "" /D F:\- Big Packets -\kitterengine\Common\ /W Template.bat

How to split the screen with two equal LinearLayouts?

Use the layout_weight attribute. The layout will roughly look like this:

<LinearLayout android:orientation="horizontal"




Operand type clash: uniqueidentifier is incompatible with int

Sounds to me like at least one of those tables has defined UserID as a uniqueidentifier, not an int. Did you check the data in each table? What does SELECT TOP 1 UserID FROM each table yield? An int or a GUID?


I think you have built a procedure based on all tables that contain a column named UserID. I think you should not have included the aspnet_Membership table in your script, since it's not really one of "your" tables.

If you meant to design your tables around the aspnet_Membership database, then why are the rest of the columns int when that table clearly uses a uniqueidentifier for the UserID column?

When to use StringBuilder in Java

As a general rule, always use the more readable code and only refactor if performance is an issue. In this specific case, most recent JDK's will actually optimize the code into the StringBuilder version in any case.

You usually only really need to do it manually if you are doing string concatenation in a loop or in some complex code that the compiler can't easily optimize.

How do I determine if a port is open on a Windows server?

Another option is tcping.

For example:

tcping host port

Parsing JSON in Excel VBA

Two small contributions to Codo's answer:

' "recursive" version of GetObjectProperty
Public Function GetObjectProperty(ByVal JsonObject As Object, ByVal propertyName As String) As Object
    Dim names() As String
    Dim i As Integer

    names = Split(propertyName, ".")

    For i = 0 To UBound(names)
        Set JsonObject = ScriptEngine.Run("getProperty", JsonObject, names(i))

    Set GetObjectProperty = JsonObject
End Function

' shortcut to object array
Public Function GetObjectArrayProperty(ByVal JsonObject As Object, ByVal propertyName As String) As Object()
    Dim a() As Object
    Dim i As Integer
    Dim l As Integer

    Set JsonObject = GetObjectProperty(JsonObject, propertyName)

    l = GetProperty(JsonObject, "length") - 1

    ReDim a(l)

    For i = 0 To l
        Set a(i) = GetObjectProperty(JsonObject, CStr(i))

    GetObjectArrayProperty = a
End Function

So now I can do stuff like:

Dim JsonObject As Object
Dim Value() As Object
Dim i As Integer
Dim Total As Double

Set JsonObject = DecodeJsonString(CStr(request.responseText))

Value = GetObjectArrayProperty(JsonObject, "d.Data")

For i = 0 To UBound(Value)
    Total = Total + Value(i).Amount

How to change the current URL in javascript?

Even it is not a good way of doing what you want try this hint: var url = MUST BE A NUMER FIRST

function nextImage (){
url = url + 1;  
location.href='' + url+'.html';

How can you find the height of text on an HTML canvas?

As JJ Stiff suggests, you can add your text to a span and then measure the offsetHeight of the span.

var d = document.createElement("span");
d.font = "20px arial";
d.textContent = "Hello world!";
var emHeight = d.offsetHeight;

As shown on HTML5Rocks

How to display loading image while actual image is downloading

Use a javascript constructor with a callback that fires when the image has finished loading in the background. Just used it and works great for me cross-browser. Here's the thread with the answer.

Setting up Eclipse with JRE Path

Add the following to the eclipse.ini :



In my Case its



Forward declaring an enum in C++

You can wrap the enum in a struct, adding in some constructors and type conversions, and forward declare the struct instead.

struct NAME { \
    enum e { VALUES }; \
    explicit NAME(TYPE v) : val(v) {} \
    NAME(e v) : val(v) {} \
    operator e() const { return e(val); } \
        TYPE val; \

This appears to work:

How to clean old dependencies from maven repositories?

It's been more than 6 years since the question was asked, but I didn't find any tool to clean up my repository. So I wrote one myself in python to get rid of old jars. Maybe it will be useful for someone:

from os.path import isdir
from os import listdir
import re
import shutil

dry_run = False #  change to True to get a log of what will be removed
m2_path = '/home/jb/.m2/repository/' #  here comes your repo path
version_regex = '^\d[.\d]*$'

def check_and_clean(path):
    files = listdir(path)
    for file in files:
        if not isdir('/'.join([path, file])):
    last = check_if_versions(files)
    if last is None:
        for file in files:
            check_and_clean('/'.join([path, file]))
    elif len(files) == 1:
        print('update ' + path.split(m2_path)[1])
        for file in files:
            if file == last:
            print(file + ' (newer version: ' + last + ')')
            if not dry_run:
                shutil.rmtree('/'.join([path, file]))

def check_if_versions(files):
    if len(files) == 0:
        return None
    last = ''
    for file in files:
        if re.match(version_regex, file):
            if last == '':
                last = file
            if len(last.split('.')) == len(file.split('.')):
                for (current, new) in zip(last.split('.'), file.split('.')):
                    if int(new) > int(current):
                        last = file
                    elif int(new) < int(current):
                return None
            return None
    return last


It recursively searches within the .m2 repository and if it finds a catalog where different versions reside it removes all of them but the newest.

Say you have the following tree somewhere in your .m2 repo:

+-- antlr
    +-- 2.7.2
    ¦   +-- antlr-2.7.2.jar
    ¦   +-- antlr-2.7.2.jar.sha1
    ¦   +-- antlr-2.7.2.pom
    ¦   +-- antlr-2.7.2.pom.sha1
    ¦   +-- _remote.repositories
    +-- 2.7.7
        +-- antlr-2.7.7.jar
        +-- antlr-2.7.7.jar.sha1
        +-- antlr-2.7.7.pom
        +-- antlr-2.7.7.pom.sha1
        +-- _remote.repositories

Then the script removes version 2.7.2 of antlr and what is left is:

+-- antlr
    +-- 2.7.7
        +-- antlr-2.7.7.jar
        +-- antlr-2.7.7.jar.sha1
        +-- antlr-2.7.7.pom
        +-- antlr-2.7.7.pom.sha1
        +-- _remote.repositories

If any old version, that you actively use, will be removed. It can easily be restored with maven (or other tools that manage dependencies).

You can get a log of what is going to be removed without actually removing it by setting dry_run = False. The output will go like this:

update /org/projectlombok/lombok
1.18.2 (newer version: 1.18.6)
1.16.20 (newer version: 1.18.6)

This means, that versions 1.16.20 and 1.18.2 of lombok will be removed and 1.18.6 will be left untouched.

The file can be found on my github (the latest version).

How to run a javascript function during a mouseover on a div

Here's a jQuery solution.

<script type="text/javascript" src="/path/to/your/copy/of/jquery-1.3.2.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
    $("#sub1").mouseover(function() {

Using this markup:

<div id="sub1">some text</div>
<div id="welcome" style="display:none;">Welcome message</div>

You didn't really specify if (or when) you wanted to hide the welcome message, but this would toggle hiding or showing each time you moused over the text.

PHP MySQL Query Where x = $variable

$result = mysqli_query($con,"SELECT `note` FROM `glogin_users` WHERE email = '".$email."'");
while($row = mysqli_fetch_array($result))
echo $row['note'];

Find OpenCV Version Installed on Ubuntu

To install this product you can see this tutorial: OpenCV on Ubuntu

There are listed the packages you need. So, with:

# dpkg -l | grep libcv2
# dpkg -l | grep libhighgui2

and more listed in the url you can find which packages are installed.


# dpkg -L libcv2

you can check where are installed

This operative is used for all debian packages.

Inline CSS styles in React: how to implement a:hover?

You can use Radium - it is an open source tool for inline styles with ReactJS. It adds exactly the selectors you need. Very popular, check it out - Radium on npm

Insert json file into mongodb

This solution is applicable for Windows machine.

  1. MongoDB needs data directory to store data. Default path is C:\data\db. In case you don't have the data directory, create one in your C: drive. (P.S.: data\db means there is a directory named 'db' inside the directory 'data')

  2. Place the json you want to import in this path: C:\data\db\ .

  3. Open the command prompt and type the following command

    mongoimport --db databaseName --collections collectionName --file fileName.json --type json --batchSize 1


  • databaseName : your database name
  • collectionName: your collection name
  • fileName: name of your json file which is in the path C:\data\db
  • batchSize can be any integer as per your wish

linking jquery in html

Seeing the answers I have nothing else to add but one more thing:

in your test.html file you have written

link rel="stylesheet" type="css/text" href="test.css"/

see where you have written


there you need to change into


so it will look like that

link rel="stylesheet" type="text/css" href="test.css"/

and in this case the CSS file will be linked to HTML file

How can I draw vertical text with CSS cross-browser?

My solution that would work on Chrome, Firefox, IE9, IE10 (Change the degrees as per your requirement):

.rotate-text {
  -webkit-transform: rotate(270deg);
  -moz-transform: rotate(270deg);
  -ms-transform: rotate(270deg);
  -o-transform: rotate(270deg);
  transform: rotate(270deg);
  filter: none; /*Mandatory for IE9 to show the vertical text correctly*/      

How to deserialize JS date using Jackson?

There is a good blog about this topic: Use @JsonFormat looks the most simple way.

public class Event {
    public String name;

      (shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy hh:mm:ss")
    public Date eventDate;

Python Tkinter clearing a frame

Returns a list of all w's children, in their stacking order from lowest (bottom) to highest (top).

for widget in frame.winfo_children():

Will destroy all the widget in your frame. No need for a second frame.

Change multiple files

You could use grep and sed together. This allows you to search subdirectories recursively.

Linux: grep -r -l <old> * | xargs sed -i 's/<old>/<new>/g'
OS X: grep -r -l <old> * | xargs sed -i '' 's/<old>/<new>/g'

For grep:
    -r recursively searches subdirectories 
    -l prints file names that contain matches
For sed:
    -i extension (Note: An argument needs to be provided on OS X)

SQL-Server: Error - Exclusive access could not be obtained because the database is in use

I got this error when there was not enough disk space to restore Db. Cleaning some space solved it.

Float vs Decimal in ActiveRecord

In Rails 3.2.18, :decimal turns into :integer when using SQLServer, but it works fine in SQLite. Switching to :float solved this issue for us.

The lesson learned is "always use homogeneous development and deployment databases!"

Open another application from your own (intent)

Try this code, Hope this will help you. If this package is available then this will open the app or else open the play store for downloads

    String  packageN = "";

            Intent i = getPackageManager().getLaunchIntentForPackage(packageN);
            if (i != null) {
            } else {
                try {
                    startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=" + packageN)));
                catch (android.content.ActivityNotFoundException anfe) {
                    startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("" + packageN)));

cartesian product in pandas

Use pd.MultiIndex.from_product as an index in an otherwise empty dataframe, then reset its index, and you're done.

a = [1, 2, 3]
b = ["a", "b", "c"]

index = pd.MultiIndex.from_product([a, b], names = ["a", "b"])

pd.DataFrame(index = index).reset_index()


   a  b
0  1  a
1  1  b
2  1  c
3  2  a
4  2  b
5  2  c
6  3  a
7  3  b
8  3  c

How to add a default "Select" option to this ASP.NET DropDownList control?

If you do an "Add" it will add it to the bottom of the list. You need to do an "Insert" if you want the item added to the top of the list.

Rails DB Migration - How To Drop a Table?

  1. rails g migration drop_users
  2. edit the migration
    class DropUsers < ActiveRecord::Migration
      def change
        drop_table :users do |t|
          t.string :name
  1. rake db:migrate

How do I define and use an ENUM in Objective-C?

Your typedef needs to be in the header file (or some other file that's #imported into your header), because otherwise the compiler won't know what size to make the PlayerState ivar. Other than that, it looks ok to me.

Python base64 data decode

(I know this is old but I wanted to post this for people like me who stumble upon it in the future) I personally just use this python code to decode base64 strings:

print open("FILE-WITH-STRING", "rb").read().decode("base64")

So you can run it in a bash script like this:

python -c 'print open("FILE-WITH-STRING", "rb").read().decode("base64")' > outputfile
file -i outputfile

twneale has also pointed out an even simpler solution: base64 -d So you can use it like this:

#Or You Can Do This
echo "STRING" | base64 -d > OUTPUTFILE

That will save the decoded string to outputfile and then attempt to identify file-type using either the file tool or you can try TrID. The following command will decode the string into a file and then use TrID to automatically identify the file's type and add the extension.

echo "STRING" | base64 -d > OUTPUTFILE; trid -ce OUTPUTFILE

Python csv string to array

csvfile can be any object which supports the iterator protocol and returns a string each time its next() method is called

Thus, a StringIO.StringIO(), str.splitlines() or even a generator are all good.

Allow only pdf, doc, docx format for file upload?

You can simply make it by REGEX:


<form method="post" action="" enctype="multipart/form-data">
    <div class="uploadExtensionError" style="display: none">Only PDF allowed!</div>
    <input type="file" name="item_file" />
    <input type="submit" id='submit' value="submit"/>

And java script validation:

    $('#submit').click(function(event) {
        var val = $('input[type=file]').val().toLowerCase();
        var regex = new RegExp("(.*?)\.(pdf|docx|doc)$");
        if(!(regex.test(val))) {


setting request headers in selenium

With the solutions already discussed above the most reliable one is using Browsermob-Proxy

But while working with the remote grid machine, Browsermob-proxy isn't really helpful.

This is how I fixed the problem in my case. Hopefully, might be helpful for anyone with a similar setup.

  1. Add the ModHeader extension to the chrome browser

How to download the Modheader? Link

ChromeOptions options = new ChromeOptions();
options.addExtensions(new File(C://Downloads//modheader//modheader.crx));

// Set the Desired capabilities 
DesiredCapabilities capabilities = new DesiredCapabilities();
capabilities.setCapability(ChromeOptions.CAPABILITY, options);

// Instantiate the chrome driver with capabilities
WebDriver driver = new RemoteWebDriver(new URL(YOUR_HUB_URL), options);
  1. Go to the browser extensions and capture the Local Storage context ID of the ModHeader

Capture ID from ModHeader

  1. Navigate to the URL of the ModHeader to set the Local Storage Context


// set the context on the extension so the localStorage can be accessed

Where `idgpnmonknjnojddfkpgkljpfnnfcklj` is the value captured from the Step# 2
  1. Now add the headers to the request using Javascript


         "localStorage.setItem('profiles', JSON.stringify([{  title: 'Selenium', hideComment: true, appendMode: '', 
             headers: [                        
               {enabled: true, name: 'token-1', value: 'value-1', comment: ''},
               {enabled: true, name: 'token-2', value: 'value-2', comment: ''}
             respHeaders: [],
             filters: []

Where token-1, value-1, token-2, value-2 are the request headers and values that are to be added.

  1. Now navigate to the required web-application.


Getting windbg without the whole WDK?

WinDbg is now available separately via MS Store. It's called "Preview" but I tested it to analyse some memory dumps and it works fine.

If you're on Windows 10 - launch MS Store, type "WinDbg" in the search box and voi-la - you have it. The download is approx. 100mb. It will downlaod required symbols automatically.

Regex for 1 or 2 digits, optional non-alphanumeric, 2 known alphas


You can test it here:

To use this in C#,

Regex r = new Regex(@"^[0-9][0-9]?[^A-Za-z0-9]?po$");
if (r.Match(someText).Success) {
   //Do Something

Remember, @ is a useful symbol that means the parser takes the string literally (eg, you don't need to write \\ for one backslash)

Git fails when pushing commit to github

I had the same issue and believe that it has to do with the size of the repo (edited- or the size of a particular file) you are trying to push.

Basically I was able to create new repos and push them to github. But an existing one would not work.

The HTTP error code seems to back me up it is a 'Length Required' error. So maybe it is too large to calc or greated that the max. Who knows.


I found that the problem may be files that are large. I had one update that would not push even though I had successful pushes up to that point. There was only one file in the commit but it happened to be 1.6M

So I added the following config change

git config http.postBuffer 524288000

To allow up to the file size 500M and then my push worked. It may have been that this was the problem initially with pushing a big repo over the http protocol.


the way I could get it to work (EDIT before I modified postBuffer) was to tar up my repo, copy it to a machine that can do git over ssh, and push it to github. Then when you try to do a push/pull from the original server it should work over https. (since it is a much smaller amount of data than an original push).

How to create a simple checkbox in iOS?

On iOS there is the switch UI component instead of a checkbox, look into the UISwitch class. The property on (boolean) can be used to determine the state of the slider and about the saving of its state: That depends on how you save your other stuff already, its just saving a boolean value.

Use multiple css stylesheets in the same html page

You never refer to a specific style sheet. All CSS rules in a document are internally fused into one.

In the case of rules in both style sheets that apply to the same element with the same specificity, the style sheet embedded later will override the earlier one.

You can use an element inspector like Firebug to see which rules apply, and which ones are overridden by others.

How can I use xargs to copy files that have spaces and quotes in their names?

Look into using the --null commandline option for xargs with the -print0 option in find.

How to identify unused CSS definitions from multiple CSS files in a project

I have just found this site –

Looks good but I would need to thoroughly check its outputted 'clean' css before uploading it to any of my sites.

Also as with all these tools I would need to check it didn't strip id's and classes with no style but are used as JavaScript selectors.

The below content is taken from so credit to them for recommending other solutions:

Latish Sehgal has written a windows application to find and remove unused CSS classes. I haven't tested it but from the description, you have to provide the path of your html files and one CSS file. The program will then list the unused CSS selectors. From the screenshot, it looks like there is no way to export this list or download a new clean CSS file. It also looks like the service is limited to one CSS file. If you have multiple files you want to clean, you have to clean them one by one.

Dust-Me Selectors is a Firefox extension (for v1.5 or later) that finds unused CSS selectors. It extracts all the selectors from all the stylesheets on the page you're viewing, then analyzes that page to see which of those selectors are not used. The data is then stored so that when testing subsequent pages, selectors can be crossed off the list as they're encountered. This tool is supposed to be able to spider a whole website but I unfortunately could make it work. Also, I don't believe you can configure and download the CSS file with the styles removed.

Topstyle is a windows application including a bunch of tools to edit CSS. I haven't tested it much but it looks like it has the ability to removed unused CSS selectors. This software costs 80 USD.

Liquidcity CSS cleaner is a php script that uses regular expressions to check the styles of one page. It will tell you the classes that aren't available in the HTML code. I haven't tested this solution.

Deadweight is a CSS coverage tool. Given a set of stylesheets and a set of URLs, it determines which selectors are actually used and lists which can be "safely" deleted. This tool is a ruby module and will only work with rails website. The unused selectors have to be manually removed from the CSS file.

Helium CSS is a javascript tool for discovering unused CSS across many pages on a web site. You first have to install the javascript file to the page you want to test. Then, you have to call a helium function to start the cleaning. is web application with an easy to use interface. Type the url of a site and you will get a list of CSS selectors. For each selector, a number indicates how many times a selector is used. This service has a few limitations. The @import statement is not supported. You can't configure and download the new clean CSS file.

CSSESS is a bookmarklet that helps you find unused CSS selectors on any site. This tool is pretty easy to use but it won't let you configure and download clean CSS files. It will only list unused CSS files.

Authenticate with GitHub using a token

Step 1: Get access token

In your github account
Click on the image on the top corner of the page that contains your profile picture ->
Settings ->
In the side menu ->
Developer Settings ->
Personal access Tokens ->
Generate new token.

Step 2: Use the token

$ git push
Username: <your username>
Password: <the access token>

Now I do not have to type username and password every time I push changes.
I just type git push and press Enter, And changes will be pushed.

Ant: How to execute a command for each file in directory?

You can use the ant-contrib task "for" to iterate on the list of files separate by any delimeter, default delimeter is ",".

Following is the sample file which shows this:

<project name="modify-files" default="main" basedir=".">
    <taskdef resource="net/sf/antcontrib/antlib.xml"/>
    <target name="main">
        <for list="FileA,FileB,FileC,FileD,FileE" param="file">
            <echo>Updating file: @{file}</echo>
            <!-- Do something with file here -->

Javascript checkbox onChange


<input type="checkbox" onchange="handleChange(event)">


function handleChange(e) {
     const {checked} =;

Laravel Eloquent limit and offset

Maybe this

$products = $art->products->take($limit)->skip($offset)->get();

Find the line number where a specific word appears with "grep"

Use grep -n to get the line number of a match.

I don't think there's a way to get grep to start on a certain line number. For that, use sed. For example, to start at line 10 and print the line number and line for matching lines, use:

sed -n '10,$ { /regex/ { =; p; } }' file

To get only the line numbers, you could use

grep -n 'regex' | sed 's/^\([0-9]\+\):.*$/\1/'

Or you could simply use sed:

sed -n '/regex/=' file

Combining the two sed commands, you get:

sed -n '10,$ { /regex/= }' file

Laravel Migration Error: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes

As already specified we add to the AppServiceProvider.php in App/Providers

use Illuminate\Support\Facades\Schema;  // add this

 * Bootstrap any application services.
 * @return void
public function boot()
    Schema::defaultStringLength(191); // also this line

you can see more details in the link bellow (search for "Index Lengths & MySQL / MariaDB")

BUT WELL THAT's not what I published all about! the thing is even when doing the above you will likely to get another error (that's when you run php artisan migrate command and because of the problem of the length, the operation will likely stuck in the middle. solution is below, and the user table is likely created without the rest or not totally correctly) we need to roll back. the default roll back will not work. because the operation of migration didn't like finish. you need to delete the new created tables in the database manually.

we can do it using tinker as in below:

L:\todos> php artisan tinker

Psy Shell v0.8.15 (PHP 7.1.10 — cli) by Justin Hileman

>>> Schema::drop('users')

=> null

I myself had a problem with users table.

after that you're good to go

php artisan migrate:rollback

php artisan migrate

Android Intent Cannot resolve constructor

You Can not Use the Intent's Context for Creating Intent. So You need to use your Fragment's Parent Activity Context

Intent intent = new Intent(getActivity(),MyClass.class);

Programmatically relaunch/recreate an activity?

I once made a test app that uploads, deletes, and then redownloads the database file using firebase cloud storage. To display the data in database, the following code was the only solution I found. Neither recreate() nor finish() worked in this case.

Intent intent = new Intent(getApplicationContext(), MainActivity.class);

C++ deprecated conversion from string constant to 'char*'

This is an error message you see whenever you have a situation like the following:

char* pointer_to_nonconst = "string literal";

Why? Well, C and C++ differ in the type of the string literal. In C the type is array of char and in C++ it is constant array of char. In any case, you are not allowed to change the characters of the string literal, so the const in C++ is not really a restriction but more of a type safety thing. A conversion from const char* to char* is generally not possible without an explicit cast for safety reasons. But for backwards compatibility with C the language C++ still allows assigning a string literal to a char* and gives you a warning about this conversion being deprecated.

So, somewhere you are missing one or more consts in your program for const correctness. But the code you showed to us is not the problem as it does not do this kind of deprecated conversion. The warning must have come from some other place.

Embed HTML5 YouTube video without iframe?

Use the object tag:

<object data="" type="text/html" width="200" height="200">
  <a href="">access the page directly</a>


How to create a listbox in HTML without allowing multiple selection?

For Asp.Net MVC

@Html.ListBox("parameterName", ViewBag.ParameterValueList as MultiSelectList, 
 new { 
 @class = "chosen-select form-control"


  @Html.ListBoxFor(model => model.parameterName,
  ViewBag.ParameterValueList as MultiSelectList,
       data_placeholder = "Select Options ",
       @class = "chosen-select form-control"

How to get GET (query string) variables in Express.js on Node.js?

app.get('/user/:id', function(req, res) {
    res.send('user' +;    

You can use this or you can try body-parser for parsing special element from the request parameters.

Convert a PHP script into a stand-alone windows executable

The current PHP Nightrain (4.0.0) is written in Python and it uses the wxPython libraries. So far wxPython has been working well to get PHP Nightrain where it is today but in order to push PHP Nightrain to its next level, we are introducing a sibling of PHP Nightrain, the PHPWebkit!

It's an update to PHP Nightrain.

How to replace all double quotes to single quotes using jquery?

You can also use replaceAll(search, replaceWith) [MDN].

Then, make sure you have a string by wrapping one type of quotes by a different type:

 'a "b" c'.replaceAll('"', "'")
 // result: "a 'b' c"
 'a "b" c'.replaceAll(`"`, `'`)
 // result: "a 'b' c"

 // Using RegEx. You MUST use a global RegEx(Meaning it'll match all occurrences).
 'a "b" c'.replaceAll(/\"/g, "'")
 // result: "a 'b' c"

Important(!) if you choose regex:

when using a regexp you have to set the global ("g") flag; otherwise, it will throw a TypeError: "replaceAll must be called with a global RegExp".

Converting integer to binary in python

A bit twiddling method...

>>> bin8 = lambda x : ''.join(reversed( [str((x >> i) & 1) for i in range(8)] ) )
>>> bin8(6)
>>> bin8(-3)

changing permission for files and folder recursively using shell command in mac

By using CHMOD yes:

For Recursive file:

chmod -R 777 foldername or pathname

For non recursive:

chmod 777 foldername or pathname

Confusion: @NotNull vs. @Column(nullable = false) with JPA and Hibernate

The most recent versions of hibernate JPA provider applies the bean validation constraints (JSR 303) like @NotNull to DDL by default (thanks to hibernate.validator.apply_to_ddl property defaults to true). But there is no guarantee that other JPA providers do or even have the ability to do that.

You should use bean validation annotations like @NotNull to ensure, that bean properties are set to a none-null value, when validating java beans in the JVM (this has nothing to do with database constraints, but in most situations should correspond to them).

You should additionally use the JPA annotation like @Column(nullable = false) to give the jpa provider hints to generate the right DDL for creating table columns with the database constraints you want. If you can or want to rely on a JPA provider like Hibernate, which applies the bean validation constraints to DDL by default, then you can omit them.

ImportError: No module named 'Tkinter'

On CentOS7, to get this working with Python2, I had to do:

yum -y install tkinter

Noting this here because I thought that there would be a pip package, but instead, one needs to actually install an rpm.

Impersonate tag in Web.Config

You had the identity node as a child of authentication node. That was the issue. As in the example above, authentication and identity nodes must be children of the system.web node

How to convert String to DOM Document object in java?

you can try

DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader("<root><node1></node1></root>"));

Document doc = db.parse(is);

refer this

ADB not responding. You can wait more,or kill "adb.exe" process manually and click 'Restart'

None of the above helped me completely. Although Oventoaster made me think. I had a couple of adb on my system. Removed them almost all.

I am running android studio on ubuntu 14.04 64 bit.

So I checked manually /home/xxxxx/Android/Sdk/platform-tools/adb

where xxxxx was my linux username

this gave

/home/xxxxx/Android/Sdk/platform-tools/adb: error while loading shared libraries: cannot open shared object file: No such file or directory

solved it for me.

How does the keyword "use" work in PHP and can I import classes with it?

use doesn't include anything. It just imports the specified namespace (or class) to the current scope

If you want the classes to be autoloaded - read about autoloading

Copy every nth line from one sheet to another

Create a macro and use the following code to grab the data and put it in a new sheet (Sheet2):

Dim strValue As String
Dim strCellNum As String
Dim x As String
x = 1

For i = 1 To 700 Step 7
    strCellNum = "A" & i
    strValue = Worksheets("Sheet1").Range(strCellNum).Value
    Debug.Print strValue
    Worksheets("Sheet2").Range("A" & x).Value = strValue
    x = x + 1

Let me know if this helps! JFV

Can I give a default value to parameters or optional parameters in C# functions?

Yes, but you'll need to be using .NET 3.5 and C# 4.0 to get this functionality.

This MSDN page has more information.

How to undo "git commit --amend" done instead of "git commit"

Find your amended commits by:

git log --reflog

Note: You may add --patch to see the body of the commits for clarity. Same as git reflog.

then reset your HEAD to any previous commit at the point it was fine by:

git reset SHA1 --hard

Note: Replace SHA1 with your real commit hash. Also note that this command will lose any uncommitted changes, so you may stash them before. Alternatively, use --soft instead to retain the latest changes and then commit them.

Then cherry-pick the other commit that you need on top of it:

git cherry-pick SHA1

"Line contains NULL byte" in CSV reader (Python)

A tricky way:

If you develop under Lunux, you can use all the power of sed:

from subprocess import check_call, CalledProcessError

PATH_TO_FILE = '/home/user/some/path/to/file.csv'

    check_call("sed -i -e 's|\\x0||g' {}".format(PATH_TO_FILE), shell=True)
except CalledProcessError as err:

The most efficient solution for huge files.

Checked for Python3, Kubuntu

How to integrate SAP Crystal Reports in Visual Studio 2017

Crystal Reports SP 19 does not support Visual Studio 2017. According to SAP they are targeting Visual Studio 2017 compatibility in SP 20 which is tentatively scheduled for June 2017.

Python to print out status bar and percentage

Per Steven C. Howell's comment on Mark Rushakoff's answer

j = (i + 1) / n
stdout.write('[%-20s] %d%%' % ('='*int(20*j), 100*j))

where i is the current item and n is the total number of items

'router-outlet' is not a known element

Assuming you are using Angular 6 with angular-cli and you have created a separate routing module which is responsible for routing activities - configure your routes in Routes array.Make sure that you are declaring RouterModule in exports array. Code would look like this:

      imports: [
     // other imports here
     exports: [RouterModule]
export class AppRoutingModule { }

MongoDB: How to find out if an array field contains an element?

It seems like the $in operator would serve your purposes just fine.

You could do something like this (pseudo-query):

if ({"students" : {"$in" : [studentId]}, "course" : courseId }).count() > 0) {
  // student is enrolled in class

Alternatively, you could remove the "course" : courseId clause and get back a set of all classes the student is enrolled in.

Oracle JDBC ojdbc6 Jar as a Maven Dependency

Add Following dependency in pom.xml


How to add a new project to Github using VS Code

Go to VS COde -> View -> Terminal

enter image description here

git init git add . git commit -m "FirstCommit" git remote add origin git pull origin master git push -f origin master

Note : Some time git push -u origin master doesn't work anticipated.

Finding first blank row, then writing to it

I would have done it like this. Short and sweet :)

Sub test()
Dim rngToSearch As Range
Dim FirstBlankCell As Range
Dim firstEmptyRow As Long

Set rngToSearch = Sheet1.Range("A:A")
    'Check first cell isn't empty
    If IsEmpty(rngToSearch.Cells(1, 1)) Then
        firstEmptyRow = rngToSearch.Cells(1, 1).Row
        Set FirstBlankCell = rngToSearch.FindNext(After:=rngToSearch.Cells(1, 1))
        If Not FirstBlankCell Is Nothing Then
            firstEmptyRow = FirstBlankCell.Row
            'no empty cell in range searched
        End If
    End If
End Sub

Updated to check if first row is empty.

Edit: Update to include check if entire row is empty

Option Explicit

Sub test()
Dim rngToSearch As Range
Dim firstblankrownumber As Long

    Set rngToSearch = Sheet1.Range("A1:C200")
    firstblankrownumber = FirstBlankRow(rngToSearch)
    Debug.Print firstblankrownumber

End Sub

Function FirstBlankRow(ByVal rngToSearch As Range, Optional activeCell As Range) As Long
Dim FirstBlankCell As Range

    If activeCell Is Nothing Then Set activeCell = rngToSearch.Cells(1, 1)
    'Check first cell isn't empty
    If WorksheetFunction.CountA(rngToSearch.Cells(1, 1).EntireRow) = 0 Then
        FirstBlankRow = rngToSearch.Cells(1, 1).Row

        Set FirstBlankCell = rngToSearch.FindNext(After:=activeCell)
        If Not FirstBlankCell Is Nothing Then

            If WorksheetFunction.CountA(FirstBlankCell.EntireRow) = 0 Then
                FirstBlankRow = FirstBlankCell.Row
                Set activeCell = FirstBlankCell
                FirstBlankRow = FirstBlankRow(rngToSearch, activeCell)

            End If
            'no empty cell in range searched
        End If
    End If
End Function

What is the command for cut copy paste a file from one directory to other directory

use the xclip which is command line interface to X selections


apt-get install xclip


echo "test xclip " > /tmp/test.xclip
xclip -i < /tmp/test.xclip
xclip -o > /tmp/test.xclip.out

cat /tmp/test.xclip.out   # "test xclip"


Cast object to interface in TypeScript

Here's another way to force a type-cast even between incompatible types and interfaces where TS compiler normally complains:

export function forceCast<T>(input: any): T {

  // ... do runtime checks here

  // @ts-ignore <-- forces TS compiler to compile this as-is
  return input;

Then you can use it to force cast objects to a certain type:

import { forceCast } from './forceCast';

const randomObject: any = {};
const typedObject = forceCast<IToDoDto>(randomObject);

Note that I left out the part you are supposed to do runtime checks before casting for the sake of reducing complexity. What I do in my project is compiling all my .d.ts interface files into JSON schemas and using ajv to validate in runtime.

How to redirect cin and cout to files?

assuming your compiles prog name is x.exe and $ is the system shell or prompt

$ x <infile >outfile 

will take input from infile and will output to outfile .

Is it possible to deserialize XML into List<T>?

Yes, it will serialize and deserialize a List<>. Just make sure you use the [XmlArray] attribute if in doubt.

public class A
    public List<string> strings;

This works with both Serialize() and Deserialize().

How can I autoformat/indent C code in vim?

I like to use the program Artistic Style. According to their website:

Artistic Style is a source code indenter, formatter, and beautifier for the C, C++, C# and Java programming languages.

It runs in Window, Linux and Mac. It will do things like indenting, replacing tabs with spaces or vice-versa, putting spaces around operations however you like (converting if(x<2) to if ( x<2 ) if that's how you like it), putting braces on the same line as function definitions, or moving them to the line below, etc. All the options are controlled by command line parameters.

In order to use it in vim, just set the formatprg option to it, and then use the gq command. So, for example, I have in my .vimrc:

autocmd BufNewFile,BufRead *.cpp set formatprg=astyle\ -T4pb

so that whenever I open a .cpp file, formatprg is set with the options I like. Then, I can type gg to go to the top of the file, and gqG to format the entire file according to my standards. If I only need to reformat a single function, I can go to the top of the function, then type gq][ and it will reformat just that function.

The options I have for astyle, -T4pb, are just my preferences. You can look through their docs, and change the options to have it format the code however you like.

Here's a demo. Before astyle:

int main(){if(x<2){x=3;}}

float test()

After astyle (gggqG):

int main()
    if (x < 2)
        x = 3;

float test()
    if (x < 2)
        x = 3;

Hope that helps.

Excel VBA, How to select rows based on data in a column?

Yes using Option Explicit is a good habit. Using .Select however is not :) it reduces the speed of the code. Also fully justify sheet names else the code will always run for the Activesheet which might not be what you actually wanted.

Is this what you are trying?

Option Explicit

Sub Sample()
    Dim lastRow As Long, i As Long
    Dim CopyRange As Range

    '~~> Change Sheet1 to relevant sheet name
    With Sheets("Sheet1")
        lastRow = .Range("A" & .Rows.Count).End(xlUp).Row

        For i = 2 To lastRow
            If Len(Trim(.Range("A" & i).Value)) <> 0 Then
                If CopyRange Is Nothing Then
                    Set CopyRange = .Rows(i)
                    Set CopyRange = Union(CopyRange, .Rows(i))
                End If
                Exit For
            End If

        If Not CopyRange Is Nothing Then
            '~~> Change Sheet2 to relevant sheet name
            CopyRange.Copy Sheets("Sheet2").Rows(1)
        End If
    End With
End Sub


If if you have data from Row 2 till Row 10 and row 11 is blank and then you have data again from Row 12 then the above code will only copy data from Row 2 till Row 10

If you want to copy all rows which have data then use this code.

Option Explicit

Sub Sample()
    Dim lastRow As Long, i As Long
    Dim CopyRange As Range

    '~~> Change Sheet1 to relevant sheet name
    With Sheets("Sheet1")
        lastRow = .Range("A" & .Rows.Count).End(xlUp).Row

        For i = 2 To lastRow
            If Len(Trim(.Range("A" & i).Value)) <> 0 Then
                If CopyRange Is Nothing Then
                    Set CopyRange = .Rows(i)
                    Set CopyRange = Union(CopyRange, .Rows(i))
                End If
            End If

        If Not CopyRange Is Nothing Then
            '~~> Change Sheet2 to relevant sheet name
            CopyRange.Copy Sheets("Sheet2").Rows(1)
        End If
    End With
End Sub

Hope this is what you wanted?


Checking if a variable exists in javascript

A variable is declared if accessing the variable name will not produce a ReferenceError. The expression typeof variableName !== 'undefined' will be false in only one of two cases:

  • the variable is not declared (i.e., there is no var variableName in scope), or
  • the variable is declared and its value is undefined (i.e., the variable's value is not defined)

Otherwise, the comparison evaluates to true.

If you really want to test if a variable is declared or not, you'll need to catch any ReferenceError produced by attempts to reference it:

var barIsDeclared = true; 
try{ bar; }
catch(e) {
    if( == "ReferenceError") {
        barIsDeclared = false;

If you merely want to test if a declared variable's value is neither undefined nor null, you can simply test for it:

if (variableName !== undefined && variableName !== null) { ... }

Or equivalently, with a non-strict equality check against null:

if (variableName != null) { ... }

Both your second example and your right-hand expression in the && operation tests if the value is "falsey", i.e., if it coerces to false in a boolean context. Such values include null, false, 0, and the empty string, not all of which you may want to discard.

Performance of FOR vs FOREACH in PHP

One thing to watch out for in benchmarks (especially, is even though the numbers are sound, the tests are not. Alot of the tests on are doing things at are trivial and abuse PHP's ability to cache array lookups to skew benchmarks or in the case of iterating over an array doesn't actually test it in real world cases (no one writes empty for loops). I've done my own benchmarks that I've found are fairly reflective of the real world results and they always show the language's native iterating syntax foreach coming out on top (surprise, surprise).

//make a nicely random array
$aHash1 = range( 0, 999999 );
$aHash2 = range( 0, 999999 );
shuffle( $aHash1 );
shuffle( $aHash2 );
$aHash = array_combine( $aHash1, $aHash2 );

$start1 = microtime(true);
foreach($aHash as $key=>$val) $aHash[$key]++;
$end1 = microtime(true);

$start2 = microtime(true);
while(list($key) = each($aHash)) $aHash[$key]++;
$end2 = microtime(true);

$start3 = microtime(true);
$key = array_keys($aHash);
$size = sizeOf($key);
for ($i=0; $i<$size; $i++) $aHash[$key[$i]]++;
$end3 = microtime(true);

$start4 = microtime(true);
foreach($aHash as &$val) $val++;
$end4 = microtime(true);

echo "foreach ".($end1 - $start1)."\n"; //foreach 0.947947025299
echo "while ".($end2 - $start2)."\n"; //while 0.847212076187
echo "for ".($end3 - $start3)."\n"; //for 0.439476966858
echo "foreach ref ".($end4 - $start4)."\n"; //foreach ref 0.0886030197144

//For these tests we MUST do an array lookup,
//since that is normally the *point* of iteration
//i'm also calling noop on it so that PHP doesn't
//optimize out the loopup.
function noop( $value ) {}

//Create an array of increasing indexes, w/ random values
$bHash = range( 0, 999999 );
shuffle( $bHash );

$bstart1 = microtime(true);
for($i = 0; $i < 1000000; ++$i) noop( $bHash[$i] );
$bend1 = microtime(true);

$bstart2 = microtime(true);
$i = 0; while($i < 1000000) { noop( $bHash[$i] ); ++$i; }
$bend2 = microtime(true);

$bstart3 = microtime(true);
foreach( $bHash as $value ) { noop( $value ); }
$bend3 = microtime(true);

echo "for ".($bend1 - $bstart1)."\n"; //for 0.397135972977
echo "while ".($bend2 - $bstart2)."\n"; //while 0.364789962769
echo "foreach ".($bend3 - $bstart3)."\n"; //foreach 0.346374034882

.htaccess or .htpasswd equivalent on IIS?

I've never used it but Trilead, a free ISAPI filter which enables .htaccess based control, looks like what you want.

Git Remote: Error: fatal: protocol error: bad line length character: Unab

Late answer here, but hope it will help someone. If its a protocol error, it has to do something with your local git not able to communicate to the remote git. This can happen if you cloned the repo via ssh and sometime later, you lost the keys to the repo or your ssh agent cannot find those keys anymore.


  1. Generate a new key and add it your git repo or configure your ssh agent to load the keys if you still have the keys with you & not with someone else ;)

  2. Another quick fix is to go to your .git directory and edit the config file's [remote "origin"] url from git to http so that ssh keys are not needed to push and it will revert to asking your username and password.

    [remote "origin"]
    url = git@gitlab.*****.com:****/****.git
    fetch = +refs/heads/*:refs/remotes/origin/*

Change to

    [remote "origin"]
    url = http://gitlab.*****.com/****/****.git
    fetch = +refs/heads/*:refs/remotes/origin/*

What is Parse/parsing?

Parsing is to read the value of one object to convert it to another type. For example you may have a string with a value of "10". Internally that string contains the Unicode characters '1' and '0' not the actual number 10. The method Integer.parseInt takes that string value and returns a real number.

String tenString = "10"

//This won't work since you can't add an integer and a string
Integer result = 20 + tenString;

//This will set result to 30
Integer result = 20 + Integer.parseInt(tenString);

Command line: search and replace in all filenames matched by grep

This is actually easier than it seems.

grep -Rl 'foo' ./ | xargs -n 1 -I % sh -c "ls %; sed -i 's/foo/bar/g' %";
  • grep recurses through your tree (-R) and prints just the file name (-l), starting at the current directory (./)
  • that gets piped to xargs, which processes them one at a time (-n 1), and uses % as a placeholder (-I %) in a shell command (sh -c)
  • in the shell command, first the file name is printed (ls %;)
  • then sed does an inline operation (-i), a substution('s/') of foo with bar (foo/bar), globally (/g) on the file (again, represented by %)

Easy peasy. If you get a good grasp on find, grep, xargs, sed, and awk, almost nothing is impossible when it comes to text file manipulation in bash :)

How to wrap text of HTML button with fixed width?

   white-space: normal;
   word-wrap: break-word;

"Both" worked for me.

Case insensitive comparison NSString

An alternative if you want more control than just case insensitivity is:

[someString compare:otherString options:NSCaseInsensitiveSearch];

Numeric search and diacritical insensitivity are two handy options.

How to reset a form using jQuery with .reset() method

you may try using trigger() Reference Link


Why do this() and super() have to be the first statement in a constructor?

The question of why Java does this has already been answered, but since I stumbled upon this question hoping to find a better alternative to the one-liner, I'll hereby share my work-around:

public class SomethingComplicated extends SomethingComplicatedParent {

    private interface Lambda<T> {
        public T run();

    public SomethingComplicated(Settings settings) {
        super(((Lambda<Settings>) () -> {

            // My modification code,
            settings.setting1 = settings.setting2;
            return settings;

Calling a static function should perform better, but I would use this if I insist on having the code "inside" the constructor, or if I have to alter multiple parameters and find defining many static methods bad for readability.

How do you express binary literals in Python?

I've tried this in Python 3.6.9

Convert Binary to Decimal

>>> 0b101111

>>> int('101111',2)

Convert Decimal to binary

>>> bin(47)

Place a 0 as the second parameter python assumes it as decimal.

>>> int('101111',0)

Showing the stack trace from a running Python application

I don't know of anything similar to java's response to SIGQUIT, so you might have to build it in to your application. Maybe you could make a server in another thread that can get a stacktrace on response to a message of some kind?

Ionic 2: Cordova is not available. Make sure to include cordova.js or run in a device/simulator (running in emulator)

This is quite late but anyone going through the same problem might benefit from this answer.First try to add browser by running below command ionic platform add browser and then run command ionic run browser.

which is the difference between ionic serve and ionic run browser?

Ionic serve - runs your app as a website (meaning it doesn't have any Cordova capabilities). Ionic run browser - runs your app in the Cordova browser platform, which will inject cordova.js and any plugins that have browser capabilities

You can refer this link to know more difference between ionic serve and ionic run browser command


From Ionic 3 this command has been changed. Use the command below instead;

ionic cordova platform add browser

ionic cordova run browser

You can find out which version of ionic you are using by running: ionic --version

how do I loop through a line from a csv file in powershell

$header3 = @("Field_1","Field_2","Field_3","Field_4","Field_5")     

Import-Csv $fileName -Header $header3 -Delimiter "`t" | select -skip 3 | Foreach-Object {

    $record = $indexName 
    foreach ($property in $_.PSObject.Properties){

        #doSomething $property.Name, $property.Value

            if($property.Name -like '*TextWrittenAsNumber*'){

                $record = $record + "," + '"' + $property.Value + '"' 
                $record = $record + "," + $property.Value 

        $array.add($record) | out-null  
        #write-host $record                         

How to show what a commit did?


git show <commit>


To show what a commit did with stats:

git show <commit> --stat


To show commit log with differences introduced for each commit in a range:

git log -p <commit1> <commit2>

What is <commit>?

Each commit has a unique id we reference here as <commit>. The unique id is an SHA-1 hash – a checksum of the content you’re storing plus a header. #TMI

If you don't know your <commit>:

  1. git log to view the commit history

  2. Find the commit you care about.

Check if at least two out of three booleans are true

public static boolean atLeast(int atLeastToBeTrue, boolean...bools){
    int booleansTrue = 0;
    for(boolean tmp : bools){
        booleansTrue += tmp ? 1 : 0;
    return booleansTrue >= atLeastToBeTrue;

You can choose how many at least you want to be true from varargs a.k.a boolean[] :-)

Disable validation of HTML5 form elements

If you mark a form element as required="" then novalidate="" does not help.

A way to circumvent the required validation is to disable the element.

How to embed a video into GitHub

For simple animations you can use an animated gif. I'm using one in this README file for instance.

How Does Modulus Divison Work

27 % 16 = 11

You can interpret it this way:

16 goes 1 time into 27 before passing it.

16 * 2 = 32.

So you could say that 16 goes one time in 27 with a remainder of 11.

In fact,

16 + 11 = 27

An other exemple:

20 % 3 = 2

Well 3 goes 6 times into 20 before passing it.

3 * 6 = 18

To add-up to 20 we need 2 so the remainder of the modulus expression is 2.

How do I make a div full screen?

When you say "full-screen", do you mean like full-screen for the computer, or for taking up the entire space in the browser?

You can't force the user into full-screen F11; however, you can make your div full screen by using the following CSS

div {width: 100%; height: 100%;}

This will of course assume your div is child of the <body> tag. Otherwise, you'd need to add the following in addition to the above code.

div {position: absolute; top: 0; left: 0;}

How to view the current heap size that an application is using?

Use this code:

// Get current size of heap in bytes
long heapSize = Runtime.getRuntime().totalMemory(); 

// Get maximum size of heap in bytes. The heap cannot grow beyond this size.// Any attempt will result in an OutOfMemoryException.
long heapMaxSize = Runtime.getRuntime().maxMemory();

 // Get amount of free memory within the heap in bytes. This size will increase // after garbage collection and decrease as new objects are created.
long heapFreeSize = Runtime.getRuntime().freeMemory(); 

It was useful to me to know it.

How to write unit testing for Angular / TypeScript for private methods with Jasmine

Do not write tests for private methods. This defeats the point of unit tests.

  • You should be testing the public API of your class
  • You should NOT be testing the implimentation details of your class


class SomeClass {

  public addNumber(a: number, b: number) {
      return a + b;

The test for this method should not need to change if later the implementation changes but the behaviour of the public API remains the same.

class SomeClass {

  public addNumber(a: number, b: number) {
      return this.add(a, b);

  private add(a: number, b: number) {
       return a + b;

Don't make methods and properties public just in order to test them. This usually means that either:

  1. You are trying to test implementation rather than API (public interface).
  2. You should move the logic in question into its own class to make testing easier.

Set value of hidden input with jquery

Suppose you have a hidden input, named XXX, if you want to assign a value to the following

<script type="text/javascript">

    $('#XXX').val('any value');

Use cases for the 'setdefault' dict method

Here are some examples of setdefault to show its usefulness:

d = {}
# To add a key->value pair, do the following:
d.setdefault(key, []).append(value)

# To retrieve a list of the values for a key
list_of_values = d[key]

# To remove a key->value pair is still easy, if
# you don't mind leaving empty lists behind when
# the last value for a given key is removed:

# Despite the empty lists, it's still possible to 
# test for the existance of values easily:
if d.has_key(key) and d[key]:
    pass # d has some values for key

# Note: Each value can exist multiple times!
e = {}
print e
e.setdefault('Cars', []).append('Toyota')
print e
e.setdefault('Motorcycles', []).append('Yamaha')
print e
e.setdefault('Airplanes', []).append('Boeing')
print e
e.setdefault('Cars', []).append('Honda')
print e
e.setdefault('Cars', []).append('BMW')
print e
e.setdefault('Cars', []).append('Toyota')
print e

# NOTE: now e['Cars'] == ['Toyota', 'Honda', 'BMW', 'Toyota']
print e
# NOTE: it's still true that ('Toyota' in e['Cars'])

typeof !== "undefined" vs. != null

If the variable is declared (either with the var keyword, as a function argument, or as a global variable), I think the best way to do it is:

if (my_variable === undefined)

jQuery does it, so it's good enough for me :-)

Otherwise, you'll have to use typeof to avoid a ReferenceError.

If you expect undefined to be redefined, you could wrap your code like this:

    // undefined is now what it's supposed to be

Or obtain it via the void operator:

const undefined = void 0;
// also safe

How to specify HTTP error code?

From what I saw in Express 4.0 this works for me. This is example of authentication required middleware.

function apiDemandLoggedIn(req, res, next) {

    // if user is authenticated in the session, carry on
    console.log('isAuth', req.isAuthenticated(), req.user);
    if (req.isAuthenticated())
        return next();

    // If not return 401 response which means unauthroized.
    var err = new Error();
    err.status = 401;

Getting error in console : Failed to load resource: net::ERR_CONNECTION_RESET

I think you are using chrome. The problem is the certificate mismatch or the expiration of the certificate.Check your certificate properly.

Just visit here for more information.