Programs & Examples On #Autotest

Autotest is a Ruby gem for running tests automatically when source files change.

How to run a single RSpec test?

Not sure how long this has bee available but there is an Rspec configuration for run filtering - so now you can add this to your spec_helper.rb:

RSpec.configure do |config|
  config.filter_run_when_matching :focus

And then add a focus tag to the it, context or describe to run only that block:

it 'runs a test', :focus do
  ...test code

RSpec documentation:

The application has stopped unexpectedly: How to Debug?

Filter your log to just Error and look for FATAL EXCEPTION

Unable to execute dex: method ID not in [0, 0xffff]: 65536

I was facing the same issue today what worked for is below down

For ANDROID STUDIO... Enable Instant Run

In File->Preferences->Build, Execution, Deployment->Instant Run-> Check Enable Instant run for hot swap...

Hope it helps

What to use now Google News API is deprecated?

I'm running into the same issue with one of my own apps. So far I've found the only non-deprecated way to access Google News data is through their RSS feeds. They have a feed for each section and also a useful search function. However, these are only for noncommercial use.

As for viable alternatives I'll be trying out these two services: Feedzilla, Daylife

Encode String to UTF-8

In Java7 you can use:

import static java.nio.charset.StandardCharsets.*;

byte[] ptext = myString.getBytes(ISO_8859_1); 
String value = new String(ptext, UTF_8); 

This has the advantage over getBytes(String) that it does not declare throws UnsupportedEncodingException.

If you're using an older Java version you can declare the charset constants yourself:

import java.nio.charset.Charset;

public class StandardCharsets {
    public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
    public static final Charset UTF_8 = Charset.forName("UTF-8");

What's the best mock framework for Java?

I started using mocks with EasyMock. Easy enough to understand, but the replay step was kinda annoying. Mockito removes this, also has a cleaner syntax as it looks like readability was one of its primary goals. I cannot stress enough how important this is, since most of developers will spend their time reading and maintaining existing code, not creating it.

Another nice thing is that interfaces and implementation classes are handled in the same way, unlike in EasyMock where still you need to remember (and check) to use an EasyMock Class Extension.

I've taken a quick look at JMockit recently, and while the laundry list of features is pretty comprehensive, I think the price of this is legibility of resulting code, and having to write more.

For me, Mockito hits the sweet spot, being easy to write and read, and dealing with majority of the situations most code will require. Using Mockito with PowerMock would be my choice.

One thing to consider is that the tool you would choose if you were developing by yourself, or in a small tight-knit team, might not be the best to get for a large company with developers of varying skill levels. Readability, ease of use and simplicity would need more consideration in the latter case. No sense in getting the ultimate mocking framework if a lot of people end up not using it or not maintaining the tests.

What's the difference between returning value or Promise.resolve from then()

You already got a good formal answer. I figured I should add a short one.

The following things are identical with Promises/A+ promises:

  • Calling Promise.resolve (In your Angular case that's $q.when)
  • Calling the promise constructor and resolving in its resolver. In your case that's new $q.
  • Returning a value from a then callback.
  • Calling Promise.all on an array with a value and then extract that value.

So the following are all identical for a promise or plain value X:

new Promise(function(resolve, reject){ resolve(x); });
Promise.resolve().then(function(){ return x; });
Promise.all([x]).then(function(arr){ return arr[0]; });

And it's no surprise, the promises specification is based on the Promise Resolution Procedure which enables easy interoperation between libraries (like $q and native promises) and makes your life overall easier. Whenever a promise resolution might occur a resolution occurs creating overall consistency.

PHP if not statements

You could also try:

if ((!isset($action)) || !($action == "add" || $action == "delete")) {
  // Do your stuff

How to persist data in a dockerized postgres database using volumes

Strangely enough, the solution ended up being to change

  - ./postgres-data:/var/lib/postgresql


  - ./postgres-data:/var/lib/postgresql/data

Loaded nib but the 'view' outlet was not set

Just spent more than hour trying to find out why my view property is not set in my view controller upon initiating it from nib. Remember to call "[super initWithNibName...]" inside your view controller's initWithNibName.

Matplotlib scatter plot with different text at each data point

As a one liner using list comprehension and numpy:

[ax.annotate(x[0], (x[1], x[2])) for x in np.array([n,z,y]).T]

setup is ditto to Rutger's answer.

Two column div layout with fluid left and fixed right column

Here's a solution (and it has some quirks, but let me know if you notice them and that they're a concern):

    <div style="width:200px;float:left;display:inline-block;">
        Hello world
    <div style="margin-left:200px;">
        Hello world

Simulator or Emulator? What is the difference?

Some years ago I came up with a very short adage that, I believe, captures the essence of the difference quite nicely:

A simulator is an emulator on a mission.

By that I mean that you use an emulator when you can't use the real thing, and you use a simulator when you can't use the real thing and you want to find something out about it.

Check status of one port on remote host

In Bash, you can use pseudo-device files which can open a TCP connection to the associated socket. The syntax is /dev/$tcp_udp/$host_ip/$port.

Here is simple example to test whether Memcached is running:

</dev/tcp/localhost/11211 && echo Port open || echo Port closed

Here is another test to see if specific website is accessible:

$ echo "HEAD / HTTP/1.0" > /dev/tcp/ && echo Connection successful.
Connection successful.

For more info, check: Advanced Bash-Scripting Guide: Chapter 29. /dev and /proc.

Related: Test if a port on a remote system is reachable (without telnet) at SuperUser.

For more examples, see: How to open a TCP/UDP socket in a bash shell (article).

Easy pretty printing of floats in python?

print "[%s]"%", ".join(map(str,yourlist))

This will avoid the rounding errors in the binary representation when printed, without introducing a fixed precision constraint (like formating with "%.2f"):

[9.0, 0.053, 0.0325754, 0.0108928, 0.0557025, 0.0793303]

Properties file with a list as the value for an individual key

Your logic is flawed... basically, you need to:

  1. get the list for the key
  2. if the list is null, create a new list and put it in the map
  3. add the word to the list

You're not doing step 2.

Here's the code you want:

Properties prop = new Properties();
prop.load(new FileInputStream("/"));
for (Map.Entry<Object, Object> entry : prop.entrySet())
    List<String> categoryList = categoryMap.get((String) entry.getKey());
    if (categoryList == null)
        categoryList = new ArrayList<String>();
        LogDisplayService.categoryMap.put((String) entry.getKey(), categoryList);
    categoryList.add((String) entry.getValue());

Note also the "correct" way to iterate over the entries of a map/properties - via its entrySet().

How do you run a Python script as a service in Windows?

The accepted answer using win32serviceutil works but is complicated and makes debugging and changes harder. It is far easier to use NSSM (the Non-Sucking Service Manager). You write and comfortably debug a normal python program and when it finally works you use NSSM to install it as a service in less than a minute:

From an elevated (admin) command prompt you run nssm.exe install NameOfYourService and you fill-in these options:

  • path: (the path to python.exe e.g. C:\Python27\Python.exe)
  • Arguments: (the path to your python script, e.g. c:\path\to\

By the way, if your program prints useful messages that you want to keep in a log file NSSM can also handle this and a lot more for you.

How to output in CLI during execution of PHP Unit tests?

Hackish, but works: Throw an exception with the debug output as its message.

class theTest extends PHPUnit_Framework_TestCase
    public function testOutput() {
        throw new \Exception("hello");


There was 1 error:

1) theTest::testOutput
Exception: hello

Access Controller method from another controller in Laravel 5

This approach also works with same hierarchy of Controller files:

$printReport = new PrintReportController;


How to convert string to double with proper cultureinfo

I have this function in my toolbelt since years ago (all the function and variable names are messy and mixing Spanish and English, sorry for that).

It lets the user use , and . to separate the decimals and will try to do the best if both symbols are used.

    Public Shared Function TryCDec(ByVal texto As String, Optional ByVal DefaultValue As Decimal = 0) As Decimal

        If String.IsNullOrEmpty(texto) Then
            Return DefaultValue
        End If

        Dim CurAsTexto As String = texto.Trim.Replace("$", "").Replace(" ", "")

        ''// You can probably use a more modern way to find out the
        ''// System current locale, this function was done long time ago
        Dim SepDecimal As String, SepMiles As String
        If CDbl("3,24") = 324 Then
            SepDecimal = "."
            SepMiles = ","
            SepDecimal = ","
            SepMiles = "."
        End If

        If InStr(CurAsTexto, SepDecimal) > 0 Then
            If InStr(CurAsTexto, SepMiles) > 0 Then
                ''//both symbols was used find out what was correct
                If InStr(CurAsTexto, SepDecimal) > InStr(CurAsTexto, SepMiles) Then
                    ''// The usage was correct, but get rid of thousand separator
                    CurAsTexto = Replace(CurAsTexto, SepMiles, "")
                    ''// The usage was incorrect, but get rid of decimal separator and then replace it
                    CurAsTexto = Replace(CurAsTexto, SepDecimal, "")
                    CurAsTexto = Replace(CurAsTexto, SepMiles, SepDecimal)
                End If
            End If
            CurAsTexto = Replace(CurAsTexto, SepMiles, SepDecimal)
        End If
        ''// At last we try to tryParse, just in case
        Dim retval As Decimal = DefaultValue
        Decimal.TryParse(CurAsTexto, retval)
        Return retval
    End Function

Select default option value from typescript angular 6

In addition to what mentioned before, you can use [attr.selected] directive to select a specific option, as follows:

    <option *ngFor="let program of programs" [attr.selected]="(member.programID ==">
        {{ }}

What does \d+ mean in regular expression terms?

\d means 'digit'. + means, '1 or more times'. So \d+ means one or more digit. It will match 12 and 1.

What is the difference between HAVING and WHERE in SQL?

When GROUP BY is not used, the WHERE and HAVING clauses are essentially equivalent.

However, when GROUP BY is used:

  • The WHERE clause is used to filter records from a result. The filtering occurs before any groupings are made.
  • The HAVING clause is used to filter values from a group (i.e., to check conditions after aggregation into groups has been performed).

How can I sanitize user input with PHP?

One trick that can help in the specific circumstance where you have a page like /mypage?id=53 and you use the id in a WHERE clause is to ensure that id definitely is an integer, like so:

if (isset($_GET['id'])) {
  $id = $_GET['id'];
  settype($id, 'integer');
  $result = mysql_query("SELECT * FROM mytable WHERE id = '$id'");
  # now use the result

But of course that only cuts out one specific attack, so read all the other answers. (And yes I know that the code above isn't great, but it shows the specific defence.)

What's the best CRLF (carriage return, line feed) handling strategy with Git?

Try setting the core.autocrlf configuration option to true. Also have a look at the core.safecrlf option.

Actually it sounds like core.safecrlf might already be set in your repository, because (emphasis mine):

If this is not the case for the current setting of core.autocrlf, git will reject the file.

If this is the case, then you might want to check that your text editor is configured to use line endings consistently. You will likely run into problems if a text file contains a mixture of LF and CRLF line endings.

Finally, I feel that the recommendation to simply "use what you're given" and use LF terminated lines on Windows will cause more problems than it solves. Git has the above options to try to handle line endings in a sensible way, so it makes sense to use them.

What's the common practice for enums in Python?

You could probably use an inheritance structure although the more I played with this the dirtier I felt.

class AnimalEnum:
  def verify(cls, other):
    return issubclass(other.__class__, cls)

class Dog(AnimalEnum):

def do_something(thing_that_should_be_an_enum):
  if not AnimalEnum.verify(thing_that_should_be_an_enum):
    raise OhGodWhy

Does Python's time.time() return the local or UTC timestamp?

There is no such thing as an "epoch" in a specific timezone. The epoch is well-defined as a specific moment in time, so if you change the timezone, the time itself changes as well. Specifically, this time is Jan 1 1970 00:00:00 UTC. So time.time() returns the number of seconds since the epoch.

How to leave/exit/deactivate a Python virtualenv

You can use virtualenvwrapper in order to ease the way you work with virtualenv.

Installing virtualenvwrapper:

pip install virtualenvwrapper

If you are using a standard shell, open your ~/.bashrc or ~/.zshrc if you use Oh My Zsh. Add these two lines:

export WORKON_HOME=$HOME/.virtualenvs
source /usr/local/bin/

To activate an existing virtualenv, use command workon:

$ workon myenv

In order to deactivate your virtualenv:

(myenv)$ deactivate

Here is my tutorial, step by step on how to install virtualenv and virtualenvwrapper.

Simpler way to create dictionary of separate variables?

Maybe I'm overthinking this but..

str_l = next((k for k,v in locals().items() if id(l) == id(v)))

>>> bar = True
>>> foo = False
>>> my_dict=dict(bar=bar, foo=foo)
>>> next((k for k,v in locals().items() if id(bar) == id(v)))
>>> next((k for k,v in locals().items() if id(foo) == id(v)))
>>> next((k for k,v in locals().items() if id(my_dict) == id(v)))

Git workflow and rebase vs merge questions

With Git there is no “correct” workflow. Use whatever floats your boat. However, if you constantly get conflicts when merging branches maybe you should coordinate your efforts better with your fellow developer(s)? Sounds like the two of you keep editing the same files. Also, watch out for whitespace and subversion keywords (i.e., “$Id$” and others).

How to get equal width of input and select fields

create another class and increase the with size with 2px example

width:278px !important; 

width:280px !important; 

How can I return to a parent activity correctly?

I tried android:launchMode="singleTask", but it didn't help. Worked for me using android:launchMode="singleInstance"

Why use 'virtual' for class properties in Entity Framework model definitions?

It’s quite common to define navigational properties in a model to be virtual. When a navigation property is defined as virtual, it can take advantage of certain Entity Framework functionality. The most common one is lazy loading.

Lazy loading is a nice feature of many ORMs because it allows you to dynamically access related data from a model. It will not unnecessarily fetch the related data until it is actually accessed, thus reducing the up-front querying of data from the database.

From book "ASP.NET MVC 5 with Bootstrap and Knockout.js"

How to Pass data from child to parent component Angular

Hello you can make use of input and output. Input let you to pass variable form parent to child. Output the same but from child to parent.

The easiest way is to pass "startdate" and "endDate" as input

<calendar [startDateInCalendar]="startDateInSearch" [endDateInCalendar]="endDateInSearch" ></calendar>

In this way you have your startdate and enddate directly in search page. Let me know if it works, or think another way. Thanks

Issue in installing php7.2-mcrypt

sudo apt-get install php-pear php7.x-dev

x is your php version like 7.2 the php7.2-dev

apt-get install libmcrypt-dev libreadline-dev
pecl install mcrypt-1.0.1 

then add "" in "/etc/php/7.2/apache2/php.ini"

here php.ini is depends on your php installatio and apache used php version.

Set the default value in dropdownlist using jQuery

$('#userZipFiles option').prop('selected', function() {
        return this.defaultSelected;

KeyListener, keyPressed versus keyTyped

You should use keyPressed if you want an immediate effect, and keyReleased if you want the effect after you release the key. You cannot use keyTyped because F5 is not a character. keyTyped is activated only when an character is pressed.

How to pass a parameter to routerLink that is somewhere inside the URL?

In your particular example you'd do the following routerLink:

[routerLink]="['user',, 'details']"

To do so in a controller, you can inject Router and use:

router.navigate(['user',, 'details']);

More info in the Angular docs Link Parameters Array section of Routing & Navigation

Getting a count of rows in a datatable that meet certain criteria

If the data is stored in a database it will be faster to send the query to the database instead of getting all data and query it in memory.

A third way to do it will be linq to datasets, but i doubt any of these 3 methods differ much in performance.

How do I install jmeter on a Mac?

The easiest way to install it is using Homebrew:

brew install jmeter

Or if you need plugins also:

brew install jmeter --with-plugins

And to open it, use the following command (since it doesn't appear in your Applications):

open /usr/local/bin/jmeter

AngularJS - Multiple ng-view in single template

You can have just one ng-view.

You can change its content in several ways: ng-include, ng-switch or mapping different controllers and templates through the routeProvider.

How do I modify fields inside the new PostgreSQL JSON datatype?

You can try updating as below:

Syntax: UPDATE table_name SET column_name = column_name::jsonb || '{"key":new_value}' WHERE column_name condition;

For your example:

UPDATE test SET data = data::jsonb || '{"a":new_value}' WHERE data->>'b' = '2';

Browse and display files in a git repo without cloning

While you have to checkout a repository, you can skip checking out any files with --no-checkout and --depth 1:

$ time git clone --no-checkout --depth 1 .
Cloning into '.'...
remote: Enumerating objects: 75646, done.
remote: Counting objects: 100% (75646/75646), done.
remote: Compressing objects: 100% (71197/71197), done.
remote: Total 75646 (delta 6176), reused 22237 (delta 3672), pack-reused 0
Receiving objects: 100% (75646/75646), 201.46 MiB | 7.27 MiB/s, done.
Resolving deltas: 100% (6176/6176), done.

real    0m46.117s
user    0m13.412s
sys     0m19.641s

And while there is only a .git directory:

$ ls -al
total 0
drwxr-xr-x   3 root  staff    96 Dec 26 23:57 .
drwxr-xr-x+ 71 root  staff  2272 Dec 27 00:03 ..
drwxr-xr-x  12 root  staff   384 Dec 26 23:58 .git

you can get a directory listing via:

$ git ls-tree --full-name --name-only -r HEAD | head

or get the number of files via:

$ git ls-tree -r HEAD | wc -l

or get the total file size via:

$ git ls-tree -l -r HEAD | awk '/^[^-]/ {s+=$4} END {print s}'

Inserting a string into a list without getting split into characters

>>> li = ['aaa', 'bbb']
>>> li.insert(0, 'wow!')
>>> li
['wow!', 'aaa', 'bbb']

CSS Classes & SubClasses

Following on from kR105's reply above:

My problem was similar to that of the OP (Original Poster), only occurred outside a table, so the subclasses were not called from within the scope of the parent class (the table), but outside of it, so I had to ADD selectors, as kR105 mentioned.

Here was the problem: I had two boxes (divs), each with the same border-radius (HTML5), padding and margin, but needed to make them different colors. Rather than repeat those 3 parameters for each color class, I wanted a "superclass" to contain border-radius/padding/margin, then just individual "subclasses" to express their differences (double quotes around each as they're not really subclasses - see my later post). Here's how it worked out:


  <div class="box box1"> Hello my color is RED </div>
  <div class="box box2"> Hello my color is BLUE </div>

CSS: {border-radius:20px 20px 20px 20px; padding:10px; margin:10px}
div.box1 {border:3px solid red; color:red}
div.box2 {border:3px solid blue; color:blue}

Hope someone finds this helpful.

How to copy static files to build directory with Webpack?

lets say all your static assets are in a folder "static" at the root level and you want copy them to the build folder maintaining the structure of subfolder, then in your entry file) just put

//index.js or index.jsx

require.context("!!file?name=[path][name].[ext]&context=./static!../static/", true, /^\.\/.*\.*/);

How can I verify if an AD account is locked?

The LockedOut property is what you are looking for among all the properties you returned. You are only seeing incomplete output in TechNet. The information is still there. You can isolate that one property using Select-Object

Get-ADUser matt -Properties * | Select-Object LockedOut


The link you referenced doesn't contain this information which is obviously misleading. Test the command with your own account and you will see much more information.

Note: Try to avoid -Properties *. While it is great for simple testing it can make queries, especially ones with multiple accounts, unnecessarily slow. So, in this case, since you only need lockedout:

Get-ADUser matt -Properties LockedOut | Select-Object LockedOut

Eclipse will not start and I haven't changed anything

I deleted the workbench.xmi in the folder workspace/.metadata/.plugins/org.eclipse.e4.workbench/.

I got this error because a build hung and then I tried to quit. However, I had unsaved changes. This prompted the following errors in logfile about unsaved changes and jobs that are not finished.

How to highlight text using javascript

Simple TypeScript example

NOTE: While I agree with @Stefan in many things, I only needed a simple match highlighting:

module myApp.Search {
    'use strict';

    export class Utils {
        private static regexFlags = 'gi';
        private static wrapper = 'mark';

        private static wrap(match: string): string {
            return '<' + Utils.wrapper + '>' + match + '</' + Utils.wrapper + '>';

        static highlightSearchTerm(term: string, searchResult: string): string {
            let regex = new RegExp(term, Utils.regexFlags);

            return searchResult.replace(regex, match => Utils.wrap(match));

And then constructing the actual result:

module myApp.Search {
    'use strict';

    export class SearchResult {
        id: string;
        title: string;

        constructor(result, term?: string) {
            this.title = term ? Utils.highlightSearchTerm(term, result.title) : result.title;

MySQL: Error dropping database (errno 13; errno 17; errno 39)

This was how I solved it:

mysql> DROP DATABASE mydatabase;
ERROR 1010 (HY000): Error dropping database (can't rmdir '.\mydatabase', errno: 13)

I went to delete this directory: C:\...\UniServerZ\core\mysql\data\mydatabase.

mysql> DROP DATABASE mydatabase;
ERROR 1008 (HY000): Can't drop database 'mydatabase'; database doesn't exist

Setting public class variables

Inside class Testclass:

public function __construct($new_value)
    $this->testvar = $new_value;

Angular HTTP GET with TypeScript error http.get(...).map is not a function in [null]

I have a solution of this problem

Install this package:

npm install rxjs@6 rxjs-compat@6 --save

then import this library

import 'rxjs/add/operator/map'

finally restart your ionic project then

ionic serve -l

Spark Dataframe distinguish columns with duplicated name

This might not be the best approach, but if you want to rename the duplicate columns(after join), you can do so using this tiny function.

def rename_duplicate_columns(dataframe):
    columns = dataframe.columns
    duplicate_column_indices = list(set([columns.index(col) for col in columns if columns.count(col) == 2]))
    for index in duplicate_column_indices:
        columns[index] = columns[index]+'2'
    dataframe = dataframe.toDF(*columns)
    return dataframe

How to POST form data with Spring RestTemplate?

Your url String needs variable markers for the map you pass to work, like:

String url = "{email}";

Or you could explicitly code the query params into the String to begin with and not have to pass the map at all, like:

String url = "[email protected]";

See also

How to create custom exceptions in Java?

To define a checked exception you create a subclass (or hierarchy of subclasses) of java.lang.Exception. For example:

public class FooException extends Exception {
  public FooException() { super(); }
  public FooException(String message) { super(message); }
  public FooException(String message, Throwable cause) { super(message, cause); }
  public FooException(Throwable cause) { super(cause); }

Methods that can potentially throw or propagate this exception must declare it:

public void calculate(int i) throws FooException, IOException;

... and code calling this method must either handle or propagate this exception (or both):

try {
  int i = 5;
} catch(FooException ex) {
  // Print error and terminate application.
} catch(IOException ex) {
  // Rethrow as FooException.
  throw new FooException(ex);

You'll notice in the above example that IOException is caught and rethrown as FooException. This is a common technique used to encapsulate exceptions (typically when implementing an API).

Sometimes there will be situations where you don't want to force every method to declare your exception implementation in its throws clause. In this case you can create an unchecked exception. An unchecked exception is any exception that extends java.lang.RuntimeException (which itself is a subclass of java.lang.Exception):

public class FooRuntimeException extends RuntimeException {

Methods can throw or propagate FooRuntimeException exception without declaring it; e.g.

public void calculate(int i) {
  if (i < 0) {
    throw new FooRuntimeException("i < 0: " + i);

Unchecked exceptions are typically used to denote a programmer error, for example passing an invalid argument to a method or attempting to breach an array index bounds.

The java.lang.Throwable class is the root of all errors and exceptions that can be thrown within Java. java.lang.Exception and java.lang.Error are both subclasses of Throwable. Anything that subclasses Throwable may be thrown or caught. However, it is typically bad practice to catch or throw Error as this is used to denote errors internal to the JVM that cannot usually be "handled" by the programmer (e.g. OutOfMemoryError). Likewise you should avoid catching Throwable, which could result in you catching Errors in addition to Exceptions.

Best way to encode Degree Celsius symbol into web page?

  1. The degree sign belongs to the number, and not to the "C". You can regard the degree sign as a number symbol, just like the minus sign.
  2. There shall not be any space between the digits and the degree sign.
  3. There shall be a non-breaking space between the degree sign and the "C".

How to make a div with a circular shape?

You can do following


<div id="circle"></div>


#circle {
    width: 100px;
    height: 100px;
    background: red;
    -moz-border-radius: 50px;
    -webkit-border-radius: 50px;
    border-radius: 50px;

Other shape SOURCE

How to force a line break in a long word in a DIV?

As mentioned in @davidcondrey's reply, there is not just the ZWSP, but also the SHY &#173; &shy; that can be used in very long, constructed words (think German or Dutch) that have to be broken on the spot you want it to be. Invisible, but it gives a hyphen the moment it's needed, thus keeping both word connected and line filled to the utmost.

That way the word luchthavenpolitieagent might be noted as lucht&shy;haven&shy;politie&shy;agent which gives longer parts than the syllables of the word.
Though I never read anything official about it, these soft hyphens manage to get higher priority in browsers than the official hyphens in the single words of the construct (if they have some extension for it at all).
In practice, no browser is capable of breaking such a long, constructed word by itself; on smaller screens resulting in a new line for it, or in some cases even a one-word-line (like when two of those constructed words follow up).

FYI: it's Dutch for airport police officer

Simple if else onclick then do?

I did it that way and I like it better, but it can be optimized, right?

// Obtengo los botones y la caja de contenido
var home = document.getElementById("home");
var about = document.getElementById("about");
var service = document.getElementById("service");
var contact = document.getElementById("contact");
var content = document.querySelector("section");

function botonPress(e){
  var screen = e.getAttribute("id");
    case "home":
      // cambiar fondo = 'black';
    case "about":
      // cambiar fondo = 'blue';
    case "service":
      // cambiar fondo = 'green';
    case "contact":
      // cambiar fondo = 'red';

How to check if JavaScript object is JSON

I wrote an npm module to solve this problem. It's available here:

object-types: a module for finding what literal types underly objects


  npm install --save object-types


const objectTypes = require('object-types');

//=> 'object'

//=> 'array'

objectTypes(new Object(true));
//=> 'boolean'

Take a look, it should solve your exact problem. Let me know if you have any questions!

How do I put a border around an Android textview?

Try this:

    <solid android:color="@color/txt_white"/>
    <stroke android:width="1dip" android:color="@color/border_black"/>

Call to undefined function curl_init().?

The CURL extension ext/curl is not installed or enabled in your PHP installation. Check the manual for information on how to install or enable CURL on your system.

Renaming Columns in an SQL SELECT Statement

you have to rename each column

SELECT col1 as MyCol1,
       col2 as MyCol2,
 FROM `foobar`

Could not load file or assembly "System.Net.Http, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"

The above bind-redirect did not work for me so I commented out the reference to System.Net.Http in web.config. Everything seems to work OK without it.

    <compilation debug="true" targetFramework="4.7.2">
        <!--<add assembly="System.Net.Http, Version=, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />-->
        <add assembly="System.ComponentModel.Composition, Version=, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
    <customErrors mode="Off" />
    <httpRuntime targetFramework="4.7.2" />

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

Typically you could use mongoose validation but since you need an async result (db query for existing names) and validators don't support promises (from what I can tell), you will need to create your own function and pass a callback. Here is an example:

var mongoose = require('mongoose'),
    Schema = mongoose.Schema,
    ObjectId = Schema.ObjectId;


var UserSchema = new Schema({
    name: {type:String}

var UserModel = mongoose.model('UserModel',UserSchema);

function updateUser(user,cb){
    UserModel.find({name :}, function (err, docs) {
        if (docs.length){
            cb('Name exists already',null);

   if (!err && existingUser){ = 'Kevin';
           if (err2 || !user){
               console.log('error updated user: ',err2);
               console.log('user updated: ',user);


UPDATE: A better way

The pre hook seems to be a more natural place to stop the save:

UserSchema.pre('save', function (next) {
    var self = this;
    UserModel.find({name :}, function (err, docs) {
        if (!docs.length){
            console.log('user exists: ',;
            next(new Error("User exists!"));
}) ;

UPDATE 2: Async custom validators

It looks like mongoose supports async custom validators now so that would probably be the natural solution:

    var userSchema = new Schema({
      name: {
        type: String,
        validate: {
          validator: function(v, cb) {
            User.find({name: v}, function(err,docs){
               cb(docs.length == 0);
          message: 'User already exists!'

What is Bootstrap?

In simpler words, you can understand Bootstrap as a front-end web framework that was created by Twitter for faster creation of device responsive web applications. Bootstrap can also be understood mostly as a collection of CSS classes that are defined in it which can simply be used directly. It makes use of CSS, javascript, jQuery etc. in the background to create the style, effects, and actions for Bootstrap elements.

You might know that we use CSS for styling webpage elements and create classes and assign classes to webpage elements to apply the style to them. Bootstrap here makes the designing simpler since we only have to include Bootstrap files and mention Bootstrap's predefined class names for our webpage elements and they will be styled automatically through Bootstrap. Through this, we get rid of writing our own CSS classes to style webpage elements. Most importantly Bootstrap is designed in such a way that makes your website device responsive and that is the main purpose of it. Other alternates for Bootstrap could be - Foundation, Materialize etc. frameworks.

Bootstrap makes you free from writing lots of CSS code and it also saves your time that you spend on designing the web pages.

Angular4 - No value accessor for form control

For me it was due to "multiple" attribute on select input control as Angular has different ValueAccessor for this type of control.

const countryControl = new FormControl();

And inside template use like this

    <select multiple name="countries" [formControl]="countryControl">
      <option *ngFor="let country of countries" [ngValue]="country">
       {{ }}

More details ref Official Docs

Indirectly referenced from required .class file

How are you adding your Weblogic classes to the classpath in Eclipse? Are you using WTP, and a server runtime? If so, is your server runtime associated with your project?

If you right click on your project and choose build path->configure build path and then choose the libraries tab. You should see the weblogic libraries associated here. If you do not you can click Add Library->Server Runtime. If the library is not there, then you first need to configure it. Windows->Preferences->Server->Installed runtimes

Unix command to find lines common in two files

Maybe you mean comm ?

Compare sorted files FILE1 and FILE2 line by line.

With no options, produce three-column output. Column one contains lines unique to FILE1, column two contains lines unique to FILE2, and column three contains lines common to both files.

The secret in finding these information are the info pages. For GNU programs, they are much more detailed than their man-pages. Try info coreutils and it will list you all the small useful utils.

oracle - what statements need to be committed?

And a key point - although TRUNCATE TABLE seems like a DELETE with no WHERE clause, TRUNCATE is not DML, it is DDL. DELETE requires a COMMIT, but TRUNCATE does not.

Re-render React component when prop changes

ComponentWillReceiveProps() is going to be deprecated in the future due to bugs and inconsistencies. An alternative solution for re-rendering a component on props change is to use ComponentDidUpdate() and ShouldComponentUpdate().

ComponentDidUpdate() is called whenever the component updates AND if ShouldComponentUpdate() returns true (If ShouldComponentUpdate() is not defined it returns true by default).

    return nextProps.changedProp !== this.state.changedProp;

    // Desired operations: ex setting state

This same behavior can be accomplished using only the ComponentDidUpdate() method by including the conditional statement inside of it.

    if(prevProps.changedProp !== this.props.changedProp){
            changedProp: this.props.changedProp

If one attempts to set the state without a conditional or without defining ShouldComponentUpdate() the component will infinitely re-render

Multiple rows to one comma-separated value in Sql Server

Test Data

INSERT INTO @Table1 VALUES (1,100),(1,200),(1,300),(1,400)


       ,STUFF((SELECT ', ' + CAST(Value AS VARCHAR(10)) [text()]
         FROM @Table1 
         WHERE ID = t.ID
         FOR XML PATH(''), TYPE)
        .value('.','NVARCHAR(MAX)'),1,2,' ') List_Output
FROM @Table1 t

Result Set

¦ ID ¦     List_Output     ¦
¦  1 ¦  100, 200, 300, 400 ¦

SQL Server 2017 and Later Versions

If you are working on SQL Server 2017 or later versions, you can use built-in SQL Server Function STRING_AGG to create the comma delimited list:

INSERT INTO @Table1 VALUES (1,100),(1,200),(1,300),(1,400);

SELECT ID , STRING_AGG([Value], ', ') AS List_Output
FROM @Table1

Result Set

¦ ID ¦     List_Output     ¦
¦  1 ¦  100, 200, 300, 400 ¦

How to find the statistical mode?

Another simple option that gives all values ordered by frequency is to use rle:

df =
df = df[order(-df$lengths),]

What do the terms "CPU bound" and "I/O bound" mean?

Multi-threading is where it tends to matter the most

In this answer, I will investigate one important use case of distinguishing between CPU vs IO bounded work: when writing multi-threaded code.

RAM I/O bound example: Vector Sum

Consider a program that sums all the values of a single vector:

#define SIZE 1000000000
unsigned int is[SIZE];
unsigned int sum = 0;
size_t i = 0;
for (i = 0; i < SIZE; i++)
    /* Each one of those requires a RAM access! */
    sum += is[i]

Parallelizing that by splitting the array equally for each of your cores is of limited usefulness on common modern desktops.

For example, on my Ubuntu 19.04, Lenovo ThinkPad P51 laptop with CPU: Intel Core i7-7820HQ CPU (4 cores / 8 threads), RAM: 2x Samsung M471A2K43BB1-CRC (2x 16GiB) I get results like this:

enter image description here

Plot data.

Note that there is a lot of variance between run however. But I can't increase the array size much further since I'm already at 8GiB, and I'm not in the mood for statistics across multiple runs today. This seemed however like a typical run after doing many manual runs.

Benchmark code:

I don't know enough computer architecture to fully explain the shape of the curve, but one thing is clear: the computation does not become 8x faster as naively expected due to me using all my 8 threads! For some reason, 2 and 3 threads was the optimum, and adding more just makes things much slower.

Compare this to CPU bound work, which actually does get 8 times faster: What do 'real', 'user' and 'sys' mean in the output of time(1)?

The reason it is all processors share a single memory bus linking to RAM:

CPU 1   --\    Bus    +-----+
CPU 2   ---\__________| RAM |
...     ---/          +-----+
CPU N   --/

so the memory bus quickly becomes the bottleneck, not the CPU.

This happens because adding two numbers takes a single CPU cycle, memory reads take about 100 CPU cycles in 2016 hardware.

So the CPU work done per byte of input data is too small, and we call this an IO-bound process.

The only way to speed up that computation further, would be to speed up individual memory accesses with new memory hardware, e.g. Multi-channel memory.

Upgrading to a faster CPU clock for example would not be very useful.

Other examples

  • matrix multiplication is CPU-bound on RAM and GPUs. The input contains:

    2 * N**2

    numbers, but:

    N ** 3

    multiplications are done, and that is enough for parallelization to be worth it for practical large N.

    This is why parallel CPU matrix multiplication libraries like the following exist:

    Cache usage makes a big difference to the speed of implementations. See for example this didactic GPU comparison example.

    See also:

  • Networking is the prototypical IO-bound example.

    Even when we send a single byte of data, it still takes a large time to reach it's destination.

    Parallelizing small network requests like HTTP requests can offer a huge performance gains.

    If the network is already at full capacity (e.g. downloading a torrent), parallelization can still increase improve the latency (e.g. you can load a web page "at the same time").

  • A dummy C++ CPU bound operation that takes one number and crunches it a lot:

  • Sorting appears to be CPU based on the following experiment: Are C++17 Parallel Algorithms implemented already? which showed a 4x performance improvement for parallel sort, but I would like to have a more theoretical confirmation as well

  • The well known Coremark benchmark from EEMBC explicitly checks how well a suite of problems scale. Sample benchmark result clearing showing that:

    Workload Name                                     (iter/s)   (iter/s)    Scaling
    ----------------------------------------------- ---------- ---------- ----------
    cjpeg-rose7-preset                                  526.32     178.57       2.95
    core                                                  7.39       2.16       3.42
    linear_alg-mid-100x100-sp                           684.93     238.10       2.88
    loops-all-mid-10k-sp                                 27.65       7.80       3.54
    nnet_test                                            32.79      10.57       3.10
    parser-125k                                          71.43      25.00       2.86
    radix2-big-64k                                     2320.19     623.44       3.72
    sha-test                                            555.56     227.27       2.44
    zip-test                                            363.64     166.67       2.18
    Mark Name                                        MultiCore SingleCore    Scaling
    ----------------------------------------------- ---------- ---------- ----------
    CoreMark-PRO                                      18743.79    6306.76       2.97
  • the linking of a C++ program can be parallelized to a certain degree: Can gcc use multiple cores when linking?

How to find out if you are CPU or IO bound

Non-RAM IO bound like disk, network: ps aux, then check if CPU% / 100 < n threads. If yes, you are IO bound, e.g. blocking reads are just waiting for data and the scheduler is skipping that process. Then use further tools like sudo iotop to decide which IO is the problem exactly.

Or, if execution is quick, and you parametrize the number of threads, you can see it easily from time that performance improves as the number of threads increases for CPU bound work: What do 'real', 'user' and 'sys' mean in the output of time(1)?

RAM-IO bound: harder to tell, as RAM wait time it is included in CPU% measurements, see also:

Some options:


GPUs have an IO bottleneck when you first transfer the input data from the regular CPU readable RAM to the GPU.

Therefore, GPUs can only be better than CPUs for CPU bound applications.

Once the data is transferred to the GPU however, it can operate on those bytes faster than the CPU can, because the GPU:

  • has more data localization than most CPU systems, and so data can be accessed faster for some cores than others

  • exploits data parallelism and sacrifices latency by just skipping over any data that is not ready to be operated on immediately.

    Since the GPU has to operate on large parallel input data, it is better to just skip to the next data that might be available instead of waiting for the current data to be come available and block all other operations like the CPU mostly does

Therefore the GPU can be faster then a CPU if your application:

  • can be highly parallelized: different chunks of data can be treated separately from one another at the same time
  • requires a large enough number of operations per input byte (unlike e.g. vector addition which does one addition per byte only)
  • there is a large number of input bytes

These designs choices originally targeted the application of 3D rendering, whose main steps are as shown at What are shaders in OpenGL and what do we need them for?

  • vertex shader: multiplying a bunch of 1x4 vectors by a 4x4 matrix
  • fragment shader: calculate the color of each pixel of a triangle based on its relative position withing the triangle

and so we conclude that those applications are CPU-bound.

With the advent of programmable GPGPU, we can observe several GPGPU applications that serve as examples of CPU bound operations:

See also:

CPython Global Intepreter Lock (GIL)

As a quick case study, I want to point out to the Python Global Interpreter Lock (GIL): What is the global interpreter lock (GIL) in CPython?

This CPython implementation detail prevents multiple Python threads from efficiently using CPU-bound work. The CPython docs say:

CPython implementation detail: In CPython, due to the Global Interpreter Lock, only one thread can execute Python code at once (even though certain performance-oriented libraries might overcome this limitation). If you want your application to make better use of the computational resources of multi-core machines, you are advised to use multiprocessing or concurrent.futures.ProcessPoolExecutor. However, threading is still an appropriate model if you want to run multiple I/O-bound tasks simultaneously.

Therefore, here we have an example where CPU-bound content is not suitable and I/O bound is.

How to convert file to base64 in JavaScript?

Here are a couple functions I wrote to get a file in a json format which can be passed around easily:

    //takes an array of JavaScript File objects
    function getFiles(files) {
        return Promise.all( => getFile(file)));

    //take a single JavaScript File object
    function getFile(file) {
        var reader = new FileReader();
        return new Promise((resolve, reject) => {
            reader.onerror = () => { reader.abort(); reject(new Error("Error parsing file"));}
            reader.onload = function () {

                //This will result in an array that will be recognized by C#.NET WebApi as a byte[]
                let bytes = Array.from(new Uint8Array(this.result));

                //if you want the base64encoded file you would use the below line:
                let base64StringFile = btoa( => String.fromCharCode(item)).join(""));

                //Resolve the promise with your custom file structure
                    bytes: bytes,
                    base64StringFile: base64StringFile,
                    fileType: file.type

    //using the functions with your file:

    file = document.querySelector('#files > input[type="file"]').files[0]
    getFile(file).then((customJsonFile) => {
         //customJsonFile is your newly constructed file.

    //if you are in an environment where async/await is supported

    files = document.querySelector('#files > input[type="file"]').files
    let customJsonFiles = await getFiles(files);
    //customJsonFiles is an array of your custom files

What is unit testing and how do you do it?

On the "How to do it" part:

I think the introduction to ScalaTest does good job of illustrating different styles of unit tests.

On the "When to do it" part:

Unit testing is not only for testing. By doing unit testing you also force the design of the software into something that is unit testable. Many people are of the opinion that this design is for the most part Good Design(TM) regardless of other benefits from testing.

So one reason to do unit test is to force your design into something that hopefully will be easier to maintain that what it would be had you not designed it for unit testing.

Ajax request returns 200 OK, but an error event is fired instead of success

I had the same problem. It was because my JSON response contains some special characters and the server file was not encoded with UTF-8, so the Ajax call considered that this was not a valid JSON response.

How do I solve this "Cannot read property 'appendChild' of null" error?

Your condition id !== 0 will always be different that zero because you are assigning a string value. On pages where the element with id views_slideshow_controls_text_next_slideshow-block is not found, you will still try to append the img element, which causes the Cannot read property 'appendChild' of null error.

Instead of assigning a string value, you can assign the DOM element and verify if it exists within the page.

window.onload = function loadContIcons() {
    var elem = document.createElement("img");
    elem.src = "";
    elem.setAttribute("class", "up_icon");

    var container = document.getElementById("views_slideshow_controls_text_next_slideshow-block");
    if (container !== null) {
    } else console.log("aaaaa");

    var elem1 = document.createElement("img");
    elem1.src = "";
    elem1.setAttribute("class", "down_icon");

    container = document.getElementById("views_slideshow_controls_text_previous_slideshow-block");
    if (container !== null) {
    } else console.log("aaaaa");

MSBuild doesn't copy references (DLL files) if using project dependencies in solution

Make sure that both projects are in the same .net version also check copy local property but this should be true as default

string to string array conversion in java

String strName = "name";
String[] strArray = new String[] {strName};
System.out.println(strArray[0]); //prints "name"

The second line allocates a String array with the length of 1. Note that you don't need to specify a length yourself, such as:

String[] strArray = new String[1];

instead, the length is determined by the number of elements in the initalizer. Using

String[] strArray = new String[] {strName, "name1", "name2"};

creates an array with a length of 3.

Fastest way to write huge data in text file Java

try memory mapped files (takes 300 m/s to write 174MB in my m/c, core 2 duo, 2.5GB RAM) :

byte[] buffer = "Help I am trapped in a fortune cookie factory\n".getBytes();
int number_of_lines = 400000;

FileChannel rwChannel = new RandomAccessFile("textfile.txt", "rw").getChannel();
ByteBuffer wrBuf =, 0, buffer.length * number_of_lines);
for (int i = 0; i < number_of_lines; i++)

Find a commit on GitHub given the commit hash

The ability to search commits has recently been added to GitHub.

To search for a hash, just enter at least the first 7 characters in the search box. Then on the results page, click the "Commits" tab to see matching commits (but only on the default branch, usually master), or the "Issues" tab to see pull requests containing the commit.

To be more explicit you can add the hash: prefix to the search, but it's not really necessary.

There is also a REST API (at the time of writing it is still in preview).

How to send HTML-formatted email?

Best way to send html formatted Email

This code will be in "Customer.htm"

            Dealer's Company Name

Read HTML file Using System.IO.File.ReadAllText. get all HTML code in string variable.

string Body = System.IO.File.ReadAllText(HttpContext.Current.Server.MapPath("EmailTemplates/Customer.htm"));

Replace Particular string to your custom value.

Body = Body.Replace("#DealerCompanyName#", _lstGetDealerRoleAndContactInfoByCompanyIDResult[0].CompanyName);

call SendEmail(string Body) Function and do procedure to send email.

 public static void SendEmail(string Body)
            MailMessage message = new MailMessage();
            message.From = new MailAddress(Session["Email"].Tostring());
            message.Subject = "Request from " + SessionFactory.CurrentCompany.CompanyName + " to add a new supplier";
            message.IsBodyHtml = true;
            message.Body = Body;

            SmtpClient smtpClient = new SmtpClient();
            smtpClient.UseDefaultCredentials = true;

            smtpClient.Host = ConfigurationSettings.AppSettings["SMTP"].ToString();
            smtpClient.Port = Convert.ToInt32(ConfigurationSettings.AppSettings["PORT"].ToString());
            smtpClient.EnableSsl = true;
            smtpClient.Credentials = new System.Net.NetworkCredential(ConfigurationSettings.AppSettings["USERNAME"].ToString(), ConfigurationSettings.AppSettings["PASSWORD"].ToString());

How can I align the columns of tables in Bash?

Use column command:

column -t -s' ' filename

How to generate a random string in Ruby

With this method you can pass in an abitrary length. It's set as a default as 6.

def generate_random_string(length=6)
  string = ""
  chars = ("A".."Z").to_a
  length.times do
    string << chars[rand(chars.length-1)]

c# dictionary one key many values

You can use a list for the second generic type. For example a dictionary of strings keyed by a string:

Dictionary<string, List<string>> myDict;

Click outside menu to close in jquery

Use the ':visible' selector. Where .menuitem is the to-hide element(s) ...


Or if you already have the .menuitem element(s) in a var ...

var menitems = $('.menuitem');

Async/Await Class Constructor

I made this test-case based on @Downgoat's answer.
It runs on NodeJS. This is Downgoat's code where the async part is provided by a setTimeout() call.

'use strict';
const util = require( 'util' );

class AsyncConstructor{

  constructor( lapse ){
    this.qqq = 'QQQ';
    this.lapse = lapse;
    return ( async ( lapse ) => {
      await this.delay( lapse );
      return this;
    })( lapse );

  async delay(ms) {
    return await new Promise(resolve => setTimeout(resolve, ms));


let run = async ( millis ) => {
  // Instatiate with await, inside an async function
  let asyncConstructed = await new AsyncConstructor( millis );
  console.log( 'AsyncConstructor: ' + util.inspect( asyncConstructed ));

run( 777 );

My use case is DAOs for the server-side of a web application.
As I see DAOs, they are each one associated to a record format, in my case a MongoDB collection like for instance a cook.
A cooksDAO instance holds a cook's data.
In my restless mind I would be able to instantiate a cook's DAO providing the cookId as an argument, and the instantiation would create the object and populate it with the cook's data.
Thus the need to run async stuff into the constructor.
I wanted to write:

let cook = new cooksDAO( '12345' );  

to have available properties like cook.getDisplayName().
With this solution I have to do:

let cook = await new cooksDAO( '12345' );  

which is very similar to the ideal.
Also, I need to do this inside an async function.

My B-plan was to leave the data loading out of the constructor, based on @slebetman suggestion to use an init function, and do something like this:

let cook = new cooksDAO( '12345' );  
async cook.getData();

which doesn't break the rules.

Check if one list contains element from the other

With java 8, we can do like below to check if one list contains any element of other list

boolean var = -> list2.contains(element)).findFirst().isPresent();

Get month name from number

I created my own function converting numbers to their corresponding month.

def month_name (number):
    if number == 1:
        return "January"
    elif number == 2:
        return "February"
    elif number == 3:
        return "March"
    elif number == 4:
        return "April"
    elif number == 5:
        return "May"
    elif number == 6:
        return "June"
    elif number == 7:
        return "July"
    elif number == 8:
        return "August"
    elif number == 9:
        return "September"
    elif number == 10:
        return "October"
    elif number == 11:
        return "November"
    elif number == 12:
        return "December"

Then I can call the function. For example:

print (month_name (12))


>>> December

Any difference between await Promise.all() and multiple await?

First difference - Fail Fast

I agree with @zzzzBov's answer, but the "fail fast" advantage of Promise.all is not the only difference. Some users in the comments have asked why using Promise.all is worth it when it's only faster in the negative scenario (when some task fails). And I ask, why not? If I have two independent async parallel tasks and the first one takes a very long time to resolve but the second is rejected in a very short time, why leave the user to wait for the longer call to finish to receive an error message? In real-life applications we must consider the negative scenario. But OK - in this first difference you can decide which alternative to use: Promise.all vs. multiple await.

Second difference - Error Handling

But when considering error handling, YOU MUST use Promise.all. It is not possible to correctly handle errors of async parallel tasks triggered with multiple awaits. In the negative scenario you will always end with UnhandledPromiseRejectionWarning and PromiseRejectionHandledWarning, regardless of where you use try/ catch. That is why Promise.all was designed. Of course someone could say that we can suppress those errors using process.on('unhandledRejection', err => {}) and process.on('rejectionHandled', err => {}) but this is not good practice. I've found many examples on the internet that do not consider error handling for two or more independent async parallel tasks at all, or consider it but in the wrong way - just using try/ catch and hoping it will catch errors. It's almost impossible to find good practice in this.


TL;DR: Never use multiple await for two or more independent async parallel tasks, because you will not be able to handle errors correctly. Always use Promise.all() for this use case.

Async/ await is not a replacement for Promises, it's just a pretty way to use promises. Async code is written in "sync style" and we can avoid multiple thens in promises.

Some people say that when using Promise.all() we can't handle task errors separately, and that we can only handle the error from the first rejected promise (separate handling can be useful e.g. for logging). This is not a problem - see "Addition" heading at the bottom of this answer.


Consider this async task...

const task = function(taskNum, seconds, negativeScenario) {
  return new Promise((resolve, reject) => {
    setTimeout(_ => {
      if (negativeScenario)
        reject(new Error('Task ' + taskNum + ' failed!'));
        resolve('Task ' + taskNum + ' succeed!');
    }, seconds * 1000)

When you run tasks in the positive scenario there is no difference between Promise.all and multiple awaits. Both examples end with Task 1 succeed! Task 2 succeed! after 5 seconds.

// Promise.all alternative
const run = async function() {
  // tasks run immediate in parallel and wait for both results
  let [r1, r2] = await Promise.all([
    task(1, 5, false),
    task(2, 5, false)
  console.log(r1 + ' ' + r2);
// at 5th sec: Task 1 succeed! Task 2 succeed!
// multiple await alternative
const run = async function() {
  // tasks run immediate in parallel
  let t1 = task(1, 5, false);
  let t2 = task(2, 5, false);
  // wait for both results
  let r1 = await t1;
  let r2 = await t2;
  console.log(r1 + ' ' + r2);
// at 5th sec: Task 1 succeed! Task 2 succeed!

However, when the first task takes 10 seconds and succeeds, and the second task takes 5 seconds but fails, there are differences in the errors issued.

// Promise.all alternative
const run = async function() {
  let [r1, r2] = await Promise.all([
      task(1, 10, false),
      task(2, 5, true)
  console.log(r1 + ' ' + r2);
// at 5th sec: UnhandledPromiseRejectionWarning: Error: Task 2 failed!
// multiple await alternative
const run = async function() {
  let t1 = task(1, 10, false);
  let t2 = task(2, 5, true);
  let r1 = await t1;
  let r2 = await t2;
  console.log(r1 + ' ' + r2);
// at 5th sec: UnhandledPromiseRejectionWarning: Error: Task 2 failed!
// at 10th sec: PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 1)
// at 10th sec: UnhandledPromiseRejectionWarning: Error: Task 2 failed!

We should already notice here that we are doing something wrong when using multiple awaits in parallel. Let's try handling the errors:

// Promise.all alternative
const run = async function() {
  let [r1, r2] = await Promise.all([
    task(1, 10, false),
    task(2, 5, true)
  console.log(r1 + ' ' + r2);
run().catch(err => { console.log('Caught error', err); });
// at 5th sec: Caught error Error: Task 2 failed!

As you can see, to successfully handle errors, we need to add just one catch to the run function and add code with catch logic into the callback. We do not need to handle errors inside the run function because async functions do this automatically - promise rejection of the task function causes rejection of the run function.

To avoid a callback we can use "sync style" (async/ await + try/ catch)
try { await run(); } catch(err) { }
but in this example it's not possible, because we can't use await in the main thread - it can only be used in async functions (because nobody wants to block main thread). To test if handling works in "sync style" we can call the run function from another async function or use an IIFE (Immediately Invoked Function Expression: MDN):

(async function() { 
  try { 
    await run(); 
  } catch(err) { 
    console.log('Caught error', err); 

This is the only correct way to run two or more async parallel tasks and handle errors. You should avoid the examples below.

Bad Examples

// multiple await alternative
const run = async function() {
  let t1 = task(1, 10, false);
  let t2 = task(2, 5, true);
  let r1 = await t1;
  let r2 = await t2;
  console.log(r1 + ' ' + r2);

We can try to handle errors in the code above in several ways...

try { run(); } catch(err) { console.log('Caught error', err); };
// at 5th sec: UnhandledPromiseRejectionWarning: Error: Task 2 failed!
// at 10th sec: UnhandledPromiseRejectionWarning: Error: Task 2 failed!
// at 10th sec: PromiseRejectionHandledWarning: Promise rejection was handled 

... nothing got caught because it handles sync code but run is async.

run().catch(err => { console.log('Caught error', err); });
// at 5th sec: UnhandledPromiseRejectionWarning: Error: Task 2 failed!
// at 10th sec: Caught error Error: Task 2 failed!
// at 10th sec: PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 1)

... huh? We see firstly that the error for task 2 was not handled and later that it was caught. Misleading and still full of errors in console, it's still unusable this way.

(async function() { try { await run(); } catch(err) { console.log('Caught error', err); }; })();
// at 5th sec: UnhandledPromiseRejectionWarning: Error: Task 2 failed!
// at 10th sec: Caught error Error: Task 2 failed!
// at 10th sec: PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 1)

... the same as above. User @Qwerty in his deleted answer asked about this strange behavior where an error seems to be caught but are also unhandled. We catch error the because run() is rejected on the line with the await keyword and can be caught using try/ catch when calling run(). We also get an unhandled error because we are calling an async task function synchronously (without the await keyword), and this task runs and fails outside the run() function.
It is similar to when we are not able to handle errors by try/ catch when calling some sync function which calls setTimeout:

function test() {
  setTimeout(function() { 
    }, 0);
try { 
} catch(e) { 
  /* this will never catch error */ 

Another poor example:

const run = async function() {
  try {
    let t1 = task(1, 10, false);
    let t2 = task(2, 5, true);
    let r1 = await t1;
    let r2 = await t2;
  catch (err) {
    return new Error(err);
  console.log(r1 + ' ' + r2);
run().catch(err => { console.log('Caught error', err); });
// at 5th sec: UnhandledPromiseRejectionWarning: Error: Task 2 failed!
// at 10th sec: PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 1)

... "only" two errors (3rd one is missing) but nothing is caught.

Addition (handling separate task errors and also first-fail error)

const run = async function() {
  let [r1, r2] = await Promise.all([
    task(1, 10, true).catch(err => { console.log('Task 1 failed!'); throw err; }),
    task(2, 5, true).catch(err => { console.log('Task 2 failed!'); throw err; })
  console.log(r1 + ' ' + r2);
run().catch(err => { console.log('Run failed (does not matter which task)!'); });
// at 5th sec: Task 2 failed!
// at 5th sec: Run failed (does not matter which task)!
// at 10th sec: Task 1 failed!

... note that in this example I rejected both tasks to better demonstrate what happens (throw err is used to fire final error).

Custom date format with jQuery validation plugin

Jon, you have some syntax errors, see below, this worked for me.

  <script type="text/javascript">
$(document).ready(function () {

      function (value, element) {
        // put your own logic here, this is just a (crappy) example 
        return value.match(/^\d\d?\/\d\d?\/\d\d\d\d$/);
      "Please enter a date in the format dd/mm/yyyy"

    rules: {
      "myDate": {
        australianDate: true


Javascript : natural sort of alphanumerical strings

Building on @Adrien Be's answer above and using the code that Brian Huisman & David koelle created, here is a modified prototype sorting for an array of objects:

//Usage: unsortedArrayOfObjects.alphaNumObjectSort("name");
//Test Case: var unsortedArrayOfObjects = [{name: "a1"}, {name: "a2"}, {name: "a3"}, {name: "a10"}, {name: "a5"}, {name: "a13"}, {name: "a20"}, {name: "a8"}, {name: "8b7uaf5q11"}];
//Sorted: [{name: "8b7uaf5q11"}, {name: "a1"}, {name: "a2"}, {name: "a3"}, {name: "a5"}, {name: "a8"}, {name: "a10"}, {name: "a13"}, {name: "a20"}]

// **Sorts in place**
Array.prototype.alphaNumObjectSort = function(attribute, caseInsensitive) {
  for (var z = 0, t; t = this[z]; z++) {
    this[z].sortArray = new Array();
    var x = 0, y = -1, n = 0, i, j;

    while (i = (j = t[attribute].charAt(x++)).charCodeAt(0)) {
      var m = (i == 46 || (i >=48 && i <= 57));
      if (m !== n) {
        this[z].sortArray[++y] = "";
        n = m;
      this[z].sortArray[y] += j;

  this.sort(function(a, b) {
    for (var x = 0, aa, bb; (aa = a.sortArray[x]) && (bb = b.sortArray[x]); x++) {
      if (caseInsensitive) {
        aa = aa.toLowerCase();
        bb = bb.toLowerCase();
      if (aa !== bb) {
        var c = Number(aa), d = Number(bb);
        if (c == aa && d == bb) {
          return c - d;
        } else {
          return (aa > bb) ? 1 : -1;

    return a.sortArray.length - b.sortArray.length;

  for (var z = 0; z < this.length; z++) {
    // Here we're deleting the unused "sortArray" instead of joining the string parts
    delete this[z]["sortArray"];

Disable output buffering

You can create an unbuffered file and assign this file to sys.stdout.

import sys 
myFile= open( "a.log", "w", 0 ) 
sys.stdout= myFile

You can't magically change the system-supplied stdout; since it's supplied to your python program by the OS.

file_get_contents("php://input") or $HTTP_RAW_POST_DATA, which one is better to get the body of JSON request?

php://input is a read-only stream that allows you to read raw data from the request body. In the case of POST requests, it is preferable to use php://input instead of $HTTP_RAW_POST_DATA as it does not depend on special php.ini directives. Moreover, for those cases where $HTTP_RAW_POST_DATA is not populated by default, it is a potentially less memory intensive alternative to activating always_populate_raw_post_data.


What is the maximum length of a Push Notification alert text?

It should be 236 bytes. There is no restriction on the size of the alert text as far as I know, but only the total payload size. So considering if the payload is minimal and only contains the alert information, it should look like:


That takes up 20 characters (20 bytes), leaving 236 bytes to put inside the alert string. With ASCII that will be 236 characters, and could be lesser with UTF8 and UTF16.

sort csv by column

import operator
sortedlist = sorted(reader, key=operator.itemgetter(3), reverse=True)

or use lambda

sortedlist = sorted(reader, key=lambda row: row[3], reverse=True)

How to fix "namespace x already contains a definition for x" error? Happened after converting to VS2010

I had this problem. It was due to me renaming a folder in the App_Code directory and releasing to my iis site folder. The original named folder was still present in my target directory - hence duplicate - (I don't do a full delete of target before copying) Anyway removing the old folder fixed this.

Mockito test a void method throws an exception

If you ever wondered how to do it using the new BDD style of Mockito:

willThrow(new Exception()).given(mockedObject).methodReturningVoid(...));

And for future reference one may need to throw exception and then do nothing:

willThrow(new Exception()).willDoNothing().given(mockedObject).methodReturningVoid(...));

CSS3 100vh not constant in mobile browser

For many of the sites I build the client will ask for a 100vh banner and just as you have found, it results in a bad "jumpy" experience on mobile when you begin to scroll. This is how I solve the problem for a smooth consistent experience across all devices:

I first set my banner element CSS to height:100vh

Then I use jQuery to get the height in pixels of my banner element and apply an inline style using this height.

var viewportHeight = $('.banner').outerHeight();
$('.banner').css({ height: viewportHeight });

Doing this solves the issue on mobile devices as when the page loads, the banner element is set to 100vh using CSS and then jQuery overrides this by putting inline CSS on my banner element which stops it from resizing when a user begins to scroll.

However, on desktop if a user resizes their browser window my banner element won't resize because it now has a fixed height set in pixels due to the above jQuery. To address this I use Mobile Detect to add a 'mobile' class to the body of my document. And then I wrap the above jQuery in an if statement:

if ($('body').hasClass('mobile')) {
  var viewportHeight = $('.banner').outerHeight();
  $('.banner').css({ height: viewportHeight });

As a result, if a user is on a mobile device the class 'mobile' is present on the body of my page and the above jQuery is executed. So my banner element will only get the inline CSS applied on mobile devices meanwhile on desktop the original 100vh CSS rule remains in place.

selenium get current url after loading a page

It's been a little while since I coded with selenium, but your code looks ok to me. One thing to note is that if the element is not found, but the timeout is passed, I think the code will continue to execute. So you can do something like this:

boolean exists = driver.findElements(By.xpath("//*[@id='someID']")).size() != 0

What does the above boolean return? And are you sure selenium actually navigates to the expected page? (That may sound like a silly question but are you actually watching the pages change... selenium can be run remotely you know...)

Exception : mockito wanted but not invoked, Actually there were zero interactions with this mock

You need to inject mock inside the class you're testing. At the moment you're interacting with the real object, not with the mock one. You can fix the code in a following way:

void testAbc(){
     myClass.myObj = myInteface;;
     verify(myInterface).myMethodToBeVerified(new String("a"), new String("b"));

although it would be a wiser choice to extract all initialization code into @Before

void setUp(){
     myClass = new myClass();
     myClass.myObj = myInteface;

void testAbc(){;
     verify(myInterface).myMethodToBeVerified(new String("a"), new String("b"));

How to build x86 and/or x64 on Windows from command line with CMAKE?



// x86

// x64

How can I position my div at the bottom of its container?

If you do not know the height of child block:

#parent {_x000D_
.child {_x000D_
<div id="parent">_x000D_
    <div class="child">child_x000D_
    </div> _x000D_

If you know the height of the child block add the child block then add padding-top/margin-top:

#parent {_x000D_
.child {_x000D_
<div id="parent">_x000D_
    <div class="child">child_x000D_
    </div> _x000D_

Difference between Amazon EC2 and AWS Elastic Beanstalk

First off, EC2 and Elastic Compute Cloud are the same thing.

Next, AWS encompasses the range of Web Services that includes EC2 and Elastic Beanstalk. It also includes many others such as S3, RDS, DynamoDB, and all the others.


EC2 is Amazon's service that allows you to create a server (AWS calls these instances) in the AWS cloud. You pay by the hour and only what you use. You can do whatever you want with this instance as well as launch n number of instances.

Elastic Beanstalk

Elastic Beanstalk is one layer of abstraction away from the EC2 layer. Elastic Beanstalk will setup an "environment" for you that can contain a number of EC2 instances, an optional database, as well as a few other AWS components such as a Elastic Load Balancer, Auto-Scaling Group, Security Group. Then Elastic Beanstalk will manage these items for you whenever you want to update your software running in AWS. Elastic Beanstalk doesn't add any cost on top of these resources that it creates for you. If you have 10 hours of EC2 usage, then all you pay is 10 compute hours.

Running Wordpress

For running Wordpress, it is whatever you are most comfortable with. You could run it straight on a single EC2 instance, you could use a solution from the AWS Marketplace, or you could use Elastic Beanstalk.

What to pick?

In the case that you want to reduce system operations and just focus on the website, then Elastic Beanstalk would be the best choice for that. Elastic Beanstalk supports a PHP stack (as well as others). You can keep your site in version control and easily deploy to your environment whenever you make changes. It will also setup an Autoscaling group which can spawn up more EC2 instances if traffic is growing.

Here's the first result off of Google when searching for "elastic beanstalk wordpress":

Posting JSON data via jQuery to ASP .NET MVC 4 controller action

//simple json object in mvc

var model = {"Id": "xx", "Name":"Ravi"};
$.ajax({    url: 'test/[ControllerName]',
                        type: "POST",
                        data: model,
                        success: function (res) {
                            if (res != null) {
                        error: function (res) {


//model in c#
public class MyModel
 public string Id {get; set;}
 public string Name {get; set;}

//controller in mvc

public ActionResult test(MyModel model)
 //now data in your model 

How to remove and clear all localStorage data


should work.

jQuery '.each' and attaching '.click' event

One solution you could use is to assign a more generalized class to any div you want the click event handler bound to.

For example:


<div id="dog" class="selected" data-selected="false">dog</div>
<div id="cat" class="selected" data-selected="true">cat</div>
<div id="mouse" class="selected" data-selected="false">mouse</div>

<div class="dog"><img/></div>
<div class="cat"><img/></div>
<div class="mouse"><img/></div>


$( ".selected" ).each(function(index) {
    $(this).on("click", function(){
        // For the boolean value
        var boolKey = $(this).data('selected');
        // For the mammal value
        var mammalKey = $(this).attr('id'); 

Draw line in UIView

Add label without text and with background color corresponding frame size(ex:height=1). Do it through code or in interface builder.

Regex empty string or email

If you are using it within rails - activerecord validation you can set allow_blank: true


validates :email, allow_blank: true, format: { with: EMAIL_REGEX }

jquery to change style attribute of a div class

In order to change the attribute of the class conditionally,

var css_val = $(".handle").css('left');
if(css_val == '336px')

If id is given as following,

<a id="handle" class="handle" href="#" style="left: 336px;"></a>

Here is an alternative solution:

var css_val = $("#handle").css('left');
if(css_val == '336px')

How to set Linux environment variables with Ansible

This is the best option. As said Michal Gasek (first answer), since the pull request was merged (, we are able to set permanent environment variables easily by play level.

- hosts: all
     - php
     - nginx
    MY_ENV_VARIABLE: whatever_value

Writing List of Strings to Excel CSV File in Python

Very simple to fix, you just need to turn the parameter to writerow into a list.

for item in RESULTS:

#define macro for debug printing in C?

I believe this variation of the theme gives debug categories without the need to have a separate macro name per category.

I used this variation in an Arduino project where program space is limited to 32K and dynamic memory is limited to 2K. The addition of debug statements and trace debug strings quickly uses up space. So it is essential to be able to limit the debug trace that is included at compile time to the minimum necessary each time the code is built.


#ifndef DEBUG_H
#define DEBUG_H

#define PRINT(DEBUG_CATEGORY, VALUE)  do { if (DEBUG_CATEGORY & DEBUG_MASK) Serial.print(VALUE);} while (0);


calling .cpp file

#define DEBUG_MASK 0x06
#include "Debug.h"

PRINT(4, "Time out error,\t");

Bind a function to Twitter Bootstrap Modal Close

Bootstrap 3 & 4

$('#myModal').on('', function () {
    // do something…

Bootstrap 3:

Bootstrap 4:

Bootstrap 2.3.2

$('#myModal').on('hidden', function () {
    // do something…

See ? Events

Python pandas insert list into a cell

Quick work around

Simply enclose the list within a new list, as done for col2 in the data frame below. The reason it works is that python takes the outer list (of lists) and converts it into a column as if it were containing normal scalar items, which is lists in our case and not normal scalars.

mydict={'col1':[1,2,3],'col2':[[1, 4], [2, 5], [3, 6]]}

   col1     col2
0   1       [1, 4]
1   2       [2, 5]
2   3       [3, 6]

How can I have same rule for two locations in NGINX config?

Another option is to repeat the rules in two prefix locations using an included file. Since prefix locations are position independent in the configuration, using them can save some confusion as you add other regex locations later on. Avoiding regex locations when you can will help your configuration scale smoothly.

server {
    location /first/location/ {
        include shared.conf;
    location /second/location/ {
        include shared.conf;

Here's a sample shared.conf:

default_type text/plain;
return 200 "http_user_agent:    $http_user_agent
remote_addr:    $remote_addr
remote_port:    $remote_port
scheme:     $scheme
nginx_version:  $nginx_version

How to run a subprocess with Python, wait for it to exit and get the full stdout as a string?

I'd try something like:

from __future__ import print_function

import shlex
from subprocess import Popen, PIPE

def shlep(cmd):
    '''shlex split and popen
    parsed_cmd = shlex.split(cmd)
    ## if parsed_cmd[0] not in approved_commands:
    ##    raise ValueError, "Bad User!  No output for you!"
    proc = Popen(parsed_command, stdout=PIPE, stderr=PIPE)
    out, err = proc.communicate()
    return (proc.returncode, out, err)

... In other words let shlex.split() do most of the work. I would NOT attempt to parse the shell's command line, find pipe operators and set up your own pipeline. If you're going to do that then you'll basically have to write a complete shell syntax parser and you'll end up doing an awful lot of plumbing.

Of course this raises the question, why not just use Popen with the shell=True (keyword) option? This will let you pass a string (no splitting nor parsing) to the shell and still gather up the results to handle as you wish. My example here won't process any pipelines, backticks, file descriptor redirection, etc that might be in the command, they'll all appear as literal arguments to the command. Thus it is still safer then running with shell=True ... I've given a silly example of checking the command against some sort of "approved command" dictionary or set --- through it would make more sense to normalize that into an absolute path unless you intend to require that the arguments be normalized prior to passing the command string to this function.

SQL Server Output Clause into a scalar variable

Way later but still worth mentioning is that you can also use variables to output values in the SET clause of an UPDATE or in the fields of a SELECT;

DECLARE @val1 int;
DECLARE @val2 int;
UPDATE [dbo].[PortalCounters_TEST]
SET @val1 = NextNum, @val2 = NextNum = NextNum + 1
WHERE [Condition] = 'unique value'
SELECT @val1, @val2

In the example above @val1 has the before value and @val2 has the after value although I suspect any changes from a trigger would not be in val2 so you'd have to go with the output table in that case. For anything but the simplest case, I think the output table will be more readable in your code as well.

One place this is very helpful is if you want to turn a column into a comma-separated list;

DECLARE @list varchar(max) = '';
DECLARE @comma varchar(2) = '';
SELECT @list = @list + @comma + County, @comma = ', ' FROM County
print @list

Swift's guard keyword

With using guard our intension is clear. we do not want to execute rest of the code if that particular condition is not satisfied. here we are able to extending chain too, please have a look at below code:

guard let value1 = number1, let value2 = number2 else { return }
 // do stuff here

Scheduled run of stored procedure on SQL server

Yes, if you use the SQL Server Agent.

Open your Enterprise Manager, and go to the Management folder under the SQL Server instance you are interested in. There you will see the SQL Server Agent, and underneath that you will see a Jobs section.

Here you can create a new job and you will see a list of steps you will need to create. When you create a new step, you can specify the step to actually run a stored procedure (type TSQL Script). Choose the database, and then for the command section put in something like:

exec MyStoredProcedure

That's the overview, post back here if you need any further advice.

[I actually thought I might get in first on this one, boy was I wrong :)]

How do you pass view parameters when navigating from an action in JSF2?

Without a nicer solution, what I found to work is simply building my query string in the bean return:

public String submit() {
    // Do something
    return "/page2.xhtml?faces-redirect=true&id=" + id;

Not the most flexible of solutions, but seems to work how I want it to.

Also using this approach to clean up the process of building the query string:

'NOT LIKE' in an SQL query

You have missed out the field name id in the second NOT LIKE. Try:

SELECT * FROM transactions WHERE id NOT LIKE '1%' AND id NOT LIKE '2%'

The AND in the where clause joins 2 full condition expressions such as id NOT LIKE '1%' and can't be used to list multiple values that the id is 'not like'.

Adjust icon size of Floating action button (fab)

What's your goal?

If set icon image size to bigger one:

  1. Make sure to have a bigger image size than your target size (so you can set max image size for your icon)

  2. My target icon image size is 84dp & fab size is 112dp:

        android:src= <image here>
        app:maxImageSize="84dp" />

Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List`1

The real problem is that you are using dynamic return type in the FacebookClient Get method. And although you use a method for serializing, the JSON converter cannot deserialize this Object after that.

Use insted of:

dynamic result = client.Get("fql", new { q = "select target_id,target_type from connection where source_id = me()"}); 
string jsonstring = JsonConvert.SerializeObject(result);

something like that:

string result = client.Get("fql", new { q = "select target_id,target_type from connection where source_id = me()"}).ToString();

Then you can use DeserializeObject method:

var datalist = JsonConvert.DeserializeObject<List<RootObject>>(result);

Hope this helps.

Setting std=c99 flag in GCC

How about alias gcc99= gcc -std=c99?

How do I prevent site scraping?

There are a few things you can do to try and prevent screen scraping. Some are not very effective, while others (a CAPTCHA) are, but hinder usability. You have to keep in mind too that it may hinder legitimate site scrapers, such as search engine indexes.

However, I assume that if you don't want it scraped that means you don't want search engines to index it either.

Here are some things you can try:

  • Show the text in an image. This is quite reliable, and is less of a pain on the user than a CAPTCHA, but means they won't be able to cut and paste and it won't scale prettily or be accessible.
  • Use a CAPTCHA and require it to be completed before returning the page. This is a reliable method, but also the biggest pain to impose on a user.
  • Require the user to sign up for an account before viewing the pages, and confirm their email address. This will be pretty effective, but not totally - a screen-scraper might set up an account and might cleverly program their script to log in for them.
  • If the client's user-agent string is empty, block access. A site-scraping script will often be lazily programmed and won't set a user-agent string, whereas all web browsers will.
  • You can set up a black list of known screen scraper user-agent strings as you discover them. Again, this will only help the lazily-coded ones; a programmer who knows what he's doing can set a user-agent string to impersonate a web browser.
  • Change the URL path often. When you change it, make sure the old one keeps working, but only for as long as one user is likely to have their browser open. Make it hard to predict what the new URL path will be. This will make it difficult for scripts to grab it if their URL is hard-coded. It'd be best to do this with some kind of script.

If I had to do this, I'd probably use a combination of the last three, because they minimise the inconvenience to legitimate users. However, you'd have to accept that you won't be able to block everyone this way and once someone figures out how to get around it, they'll be able to scrape it forever. You could then just try to block their IP addresses as you discover them I guess.

Is an entity body allowed for an HTTP DELETE request?

It seems ElasticSearch uses this:

Which means Netty support this.

Like mentionned in comments it may not be the case anymore

How do I determine the current operating system with Node.js

With Node.js v6 (and above) there is a dedicated os module, which provides a number of operating system-related utility methods.

On my Windows 10 machine it reports the following:

var os = require('os');

console.log(os.type()); // "Windows_NT"
console.log(os.release()); // "10.0.14393"
console.log(os.platform()); // "win32"

You can read it's full documentation here:

Python - OpenCV - imread - Displaying Image

Looks like the image is too big and the window simply doesn't fit the screen. Create window with the cv2.WINDOW_NORMAL flag, it will make it scalable. Then you can resize it to fit your screen like this:

from __future__ import division
import cv2

img = cv2.imread('1.jpg')

screen_res = 1280, 720
scale_width = screen_res[0] / img.shape[1]
scale_height = screen_res[1] / img.shape[0]
scale = min(scale_width, scale_height)
window_width = int(img.shape[1] * scale)
window_height = int(img.shape[0] * scale)

cv2.namedWindow('dst_rt', cv2.WINDOW_NORMAL)
cv2.resizeWindow('dst_rt', window_width, window_height)

cv2.imshow('dst_rt', img)

According to the OpenCV documentation CV_WINDOW_KEEPRATIO flag should do the same, yet it doesn't and it's value not even presented in the python module.

What's the proper value for a checked attribute of an HTML checkbox?

HTML5 spec: :

The disabled content attribute is a boolean attribute. :

The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.

If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace.


The following are valid, equivalent and true:

<input type="checkbox" checked />
<input type="checkbox" checked="" />
<input type="checkbox" checked="checked" />
<input type="checkbox" checked="ChEcKeD" />

The following are invalid:

<input type="checkbox" checked="0" />
<input type="checkbox" checked="1" />
<input type="checkbox" checked="false" />
<input type="checkbox" checked="true" />

The absence of the attribute is the only valid syntax for false:

<input />


If you care about writing valid XHTML, use checked="checked", since <input checked> is invalid XHTML (but valid HTML) and other alternatives are less readable. Else, just use <input checked> as it is shorter.

ALTER DATABASE failed because a lock could not be placed on database

I managed to reproduce this error by doing the following.

Connection 1 (leave running for a couple of minutes)



FROM sys.objects s1,sys.objects s2,sys.objects s3,sys.objects s4 ,sys.objects s5 ,sys.objects s6

Connections 2 and 3

set lock_timeout 5;


Mod of negative number is melting my brain

Adding some understanding.

By Euclidean definition the mod result must be always positive.


 int n = 5;
 int x = -3;

 int mod(int n, int x)
     return ((n%x)+x)%x;



The target principal name is incorrect. Cannot generate SSPI context

Login to both your SQL Box and your client and type:

ipconfig /flushdns
nbtstat -R

If that doesn't work, renew your DHCP on your client machine... This work for 2 PCs in our office.

How much memory can a 32 bit process access on a 64 bit operating system?

You've got the same basic restriction when running a 32bit process under Win64. Your app runs in a 32 but subsystem which does its best to look like Win32, and this will include the memory restrictions for your process (lower 2GB for you, upper 2GB for the OS)

c# Image resizing to different size while preserving aspect ratio

// This allows us to resize the image. It prevents skewed images and 
// also vertically long images caused by trying to maintain the aspect 
// ratio on images who's height is larger than their width

public void ResizeImage(string OriginalFile, string NewFile, int NewWidth, int MaxHeight, bool OnlyResizeIfWider)

    System.Drawing.Image FullsizeImage = System.Drawing.Image.FromFile(OriginalFile);

    // Prevent using images internal thumbnail

    if (OnlyResizeIfWider)
        if (FullsizeImage.Width <= NewWidth)
            NewWidth = FullsizeImage.Width;

    int NewHeight = FullsizeImage.Height * NewWidth / FullsizeImage.Width;
    if (NewHeight > MaxHeight)
        // Resize with height instead
        NewWidth = FullsizeImage.Width * MaxHeight / FullsizeImage.Height;
        NewHeight = MaxHeight;

    System.Drawing.Image NewImage = FullsizeImage.GetThumbnailImage(NewWidth, NewHeight, null, IntPtr.Zero);

    // Clear handle to original file so that we can overwrite it if necessary

    // Save resized picture

Copying a local file from Windows to a remote server using scp

I have found it easiest to use a graphical interface on windows (I recommend mobaXTerm it has ssh, scp, ftp, remote desktop, and many more) but if you are set on command line I would recommend cd'ing into the directory with the source folder then
scp -r yourFolder username@server:/path/to/dir
the -r indicates recursive to be used on directories

Should I size a textarea with CSS width / height or HTML cols / rows attributes?

YES!....always style textarea using CSS and avoid the attributes, unless you need to support some very old agent that does not support style sheets. Otherwise, you have full power to use CSS. Below is my default CSS formatting for textarea that looks beautiful in any website. Customize it as you like. Comments are included below so you can see why I chose those CSS properties and values:

textarea {
    display: inline-block;
    margin: 0;
    padding: .2em;
    width: auto;
    min-width: 30em;
    /* The max-width "100%" value fixes a weird issue where width is too wide by default and extends beyond 100% of the parent in some agents. */
    max-width: 100%;
    /* Height "auto" will allow the text area to expand vertically in size with a horizontal scrollbar if pre-existing content is added to the box before rendering. Remove this if you want a pre-set height. Use "em" to match the font size set in the website. */
    height: auto;
    /* Use "em" to define the height based on the text size set in your website and the text rows in the box, not a static pixel value. */
    min-height: 10em;
    /* Do not use "border" in textareas unless you want to remove the 3D box most browsers assign and flatten the box design. */
    /*border: 1px solid black;*/
    cursor: text;
    /* Some textareas have a light gray background by default anyway. */
    background-color: #eee;
    /* Overflow "auto" allows the box to start with no scrollbars but add them as content fills the box. */
    overflow: auto;
    /* Resize creates a tab in the lower right corner of textarea for most modern browsers and allows users to resize the box manually. Note: Resize isn't supported by most older agents and IE. */
    resize: both;

In my "reset" element style sheet I set these values as defaults for "textarea" by default, which give all your textareas a nice look and feel with scrolling when detected, a resizing tab (non-IE browsers), and fixes for dimensions, including a height that allows the box to size itself based on existing content you put in it for the user and a width that does not break out beyond its parent containers limitations.

How can I reverse a NSArray in Objective-C?

Or the Scala-way:

-(NSArray *)reverse
    if ( self.count < 2 )
        return self;
        return [[self.tail reverse] concat:[NSArray arrayWithObject:self.head]];

    return self.firstObject;

-(NSArray *)tail
    if ( self.count > 1 )
        return [self subarrayWithRange:NSMakeRange(1, self.count - 1)];
        return @[];

Difference between Visibility.Collapsed and Visibility.Hidden

Even though a bit old thread, for those who still looking for the differences:

Aside from layout (space) taken in Hidden and not taken in Collapsed, there is another difference.

If we have custom controls inside this 'Collapsed' main control, the next time we set it to Visible, it will "load" all custom controls. It will not pre-load when window is started.

As for 'Hidden', it will load all custom controls + main control which we set as hidden when the "window" is started.

Check if a string matches a regex in Bash script

A good way to test if a string is a correct date is to use the command date:

if date -d "${DATE}" >/dev/null 2>&1
  # do what you need to do with your date
  echo "${DATE} incorrect date" >&2
  exit 1

from comment: one can use formatting

if [ "2017-01-14" == $(date -d "2017-01-14" '+%Y-%m-%d') ] 

Why can't I duplicate a slice with `copy()`?

The Go Programming Language Specification

Appending to and copying slices

The function copy copies slice elements from a source src to a destination dst and returns the number of elements copied. Both arguments must have identical element type T and must be assignable to a slice of type []T. The number of elements copied is the minimum of len(src) and len(dst). As a special case, copy also accepts a destination argument assignable to type []byte with a source argument of a string type. This form copies the bytes from the string into the byte slice.

copy(dst, src []T) int
copy(dst []byte, src string) int

tmp needs enough room for arr. For example,

package main

import "fmt"

func main() {
    arr := []int{1, 2, 3}
    tmp := make([]int, len(arr))
    copy(tmp, arr)


[1 2 3]
[1 2 3]

Open existing file, append a single line

We can use

public StreamWriter(string path, bool append);

while opening the file

string path="C:\\MyFolder\\Notes.txt"
StreamWriter writer = new StreamWriter(path, true);

First parameter is a string to hold a full file path Second parameter is Append Mode, that in this case is made true

Writing to the file can be done with:




Sample Code

private void WriteAndAppend()
            string Path = Application.StartupPath + "\\notes.txt";
            FileInfo fi = new FileInfo(Path);
            StreamWriter SW;
            StreamReader SR;
            if (fi.Exists)
                SR = new StreamReader(Path);
                string Line = "";
                while (!SR.EndOfStream) // Till the last line
                    Line = SR.ReadLine();
                int x = 0;
                if (Line.Trim().Length <= 0)
                    x = 0;
                    x = Convert.ToInt32(Line.Substring(0, Line.IndexOf('.')));
                SW = new StreamWriter(Path, true);
                SW.WriteLine("-----"+string.Format("{0:dd-MMM-yyyy hh:mm:ss tt}", DateTime.Now));
                SW.WriteLine(x.ToString() + "." + textBox1.Text);

                SW = new StreamWriter(Path);
                SW.WriteLine("-----" + string.Format("{0:dd-MMM-yyyy hh:mm:ss tt}", DateTime.Now));
                SW.WriteLine("1." + textBox1.Text);

Python: PIP install path, what is the correct location for this and other addons?

Since pip is an executable and which returns path of executables or filenames in environment. It is correct. Pip module is installed in site-packages but the executable is installed in bin.

Kill all processes for a given user

What about iterating on the /proc virtual file system ? ?

How to set a value to a file input in HTML?

Not an answer to your question (which others have answered), but if you want to have some edit functionality of an uploaded file field, what you probably want to do is:

  • show the current value of this field by just printing the filename or URL, a clickable link to download it, or if it's an image: just show it, possibly as thumbnail
  • the <input> tag to upload a new file
  • a checkbox that, when checked, deletes the currently uploaded file. note that there's no way to upload an 'empty' file, so you need something like this to clear out the field's value

Scaling an image to fit on canvas

Provide the source image (img) size as the first rectangle:

ctx.drawImage(img, 0, 0, img.width,    img.height,     // source rectangle
                   0, 0, canvas.width, canvas.height); // destination rectangle

The second rectangle will be the destination size (what source rectangle will be scaled to).

Update 2016/6: For aspect ratio and positioning (ala CSS' "cover" method), check out:
Simulation background-size: cover in canvas

Making a request to a RESTful API using python

Below is the program to execute the rest api in python-

import requests
url = 'https://url'
data = '{  "platform": {    "login": {      "userName": "name",      "password": "pwd"    }  } }'
response =, data=data,headers={"Content-Type": "application/json"})
sid=response.json()['platform']['login']['sessionId']   //to extract the detail from response

How to make audio autoplay on chrome

Solution #1

My solution here is to create an iframe

<iframe src="audio/source.mp3" allow="autoplay" style="display:none" id="iframeAudio">

and audio tag aswell for non-chrome browsers

<audio autoplay loop  id="playAudio">
    <source src="audio/source.mp3">

and in my script

  var isChrome = /Chrome/.test(navigator.userAgent) && /Google Inc/.test(navigator.vendor);
  if (!isChrome){
  else {
      $('#playAudio').remove() // just to make sure that it will not have 2x audio in the background 

Solution #2:

There is also another workaround for this according to @Leonard

Create an iframe that doesn't play anything just to trigger the autoplay in the first load.

<iframe src="silence.mp3" allow="autoplay" id="audio" style="display: none"></iframe>

good source for the mp3 file silence.mp3

Then play your real audio file at ease.

<audio id="player" autoplay loop>
    <source src="audio/source.mp3" type="audio/mp3">

Personally I prefer solution #2 because it is cleaner approach for not relying so much in JavaScript.

Update August 2019

Solution #3

As an alternative we can use <embed>

For Firefox It seems that audio auto-play is working so we don't need the <embed> element because it will create double audio running.

// index.js
let audioPlaying = true,
    backgroundAudio, browser;
browser = navigator.userAgent.toLowerCase();
$('<audio class="audio1" src="audio.mp3" loop></audio>').prependTo('body');
if (!browser.indexOf('firefox') > -1) {
    $('<embed id="background-audio" src="audio.mp3" autostart="1"></embed>').prependTo('body');
    backgroundAudio = setInterval(function() {
        $('<embed id="background-audio" src="audio.mp3"></embed>').prependTo('body');
    }, 120000); // 120000 is the duration of your audio which in this case 2 mins.

Also if you have a toggle event for your audio make sure to remove the created <embed> element for audio.

Note: After your toggle, it will restart from the beginning because the <embed> is already deleted and the <audio> element will play as normal now.

$(".toggle-audio").on('click', function(event) {
    audioPlaying = !audioPlaying;

    if (audioPlaying){
        // play audio 
    else {

And now make sure to hide these <audio> and <embed> elements

audio, embed {
    position: absolute;
    z-index: -9999;

Note: diplay: none and visibility: hidden will make the <embed> element not work.

Can't install any packages in Node.js using "npm install"

I found the there is a certificate expired issue with:

npm set registry

So I made it http, not https :-

npm set registry

And have no problems so far.

How do I use the ternary operator ( ? : ) in PHP as a shorthand for "if / else"?

It's the Ternary operator a.k.a Elvis operator (google it :P) you are looking for.

echo $address['street2'] ?: 'Empty'; 

It returns the value of the variable or default if the variable is empty.

Is System.nanoTime() completely useless?

nanoTime is extremely insecure for timing. I tried it out on my basic primality testing algorithms and it gave answers which were literally one second apart for the same input. Don't use that ridiculous method. I need something that is more accurate and precise than get time millis, but not as bad as nanoTime.

Disable Copy or Paste action for text box?


oncopy="return false" onpaste="return false"

Email: <input type="textbox" id="email" oncopy="return false" onpaste="return false" ><br/>
Confirm Email:    <input type="textbox" id="confirmEmail" oncopy="return false" onpaste="return false">

Array inside a JavaScript Object?

var defaults = {_x000D_
  "background-color": "#000",_x000D_
  color: "#fff",_x000D_
  weekdays: [_x000D_
    {0: 'sun'},_x000D_
    {1: 'mon'},_x000D_
    {2: 'tue'},_x000D_
    {3: 'wed'},_x000D_
    {4: 'thu'},_x000D_
    {5: 'fri'},_x000D_
    {6: 'sat'}_x000D_

Flatten an irregular list of lists

Here is another py2 approach, Im not sure if its the fastest or the most elegant nor safest ...

from collections import Iterable
from itertools import imap, repeat, chain

def flat(seqs, ignore=(int, long, float, basestring)):
    return repeat(seqs, 1) if any(imap(isinstance, repeat(seqs), ignore)) or not isinstance(seqs, Iterable) else chain.from_iterable(imap(flat, seqs))

It can ignore any specific (or derived) type you would like, it returns an iterator, so you can convert it to any specific container such as list, tuple, dict or simply consume it in order to reduce memory footprint, for better or worse it can handle initial non-iterable objects such as int ...

Note most of the heavy lifting is done in C, since as far as I know thats how itertools are implemented, so while it is recursive, AFAIK it isn't bounded by python recursion depth since the function calls are happening in C, though this doesn't mean you are bounded by memory, specially in OS X where its stack size has a hard limit as of today (OS X Mavericks) ...

there is a slightly faster approach, but less portable method, only use it if you can assume that the base elements of the input can be explicitly determined otherwise, you'll get an infinite recursion, and OS X with its limited stack size, will throw a segmentation fault fairly quickly ...

def flat(seqs, ignore={int, long, float, str, unicode}):
    return repeat(seqs, 1) if type(seqs) in ignore or not isinstance(seqs, Iterable) else chain.from_iterable(imap(flat, seqs))

here we are using sets to check for the type so it takes O(1) vs O(number of types) to check whether or not an element should be ignored, though of course any value with derived type of the stated ignored types will fail, this is why its using str, unicode so use it with caution ...


import random

def test_flat(test_size=2000):
    def increase_depth(value, depth=1):
        for func in xrange(depth):
            value = repeat(value, 1)
        return value

    def random_sub_chaining(nested_values):
        for values in nested_values:
            yield chain((values,), chain.from_iterable(imap(next, repeat(nested_values, random.randint(1, 10)))))

    expected_values = zip(xrange(test_size), imap(str, xrange(test_size)))
    nested_values = random_sub_chaining((increase_depth(value, depth) for depth, value in enumerate(expected_values)))
    assert not any(imap(cmp, chain.from_iterable(expected_values), flat(chain(((),), nested_values, ((),)))))

>>> test_flat()
>>> list(flat([[[1, 2, 3], [4, 5]], 6]))
[1, 2, 3, 4, 5, 6]

$ uname -a
Darwin Samys-MacBook-Pro.local 13.3.0 Darwin Kernel Version 13.3.0: Tue Jun  3 21:27:35 PDT 2014; root:xnu-2422.110.17~1/RELEASE_X86_64 x86_64
$ python --version
Python 2.7.5

Match multiline text using regular expression

First, you're using the modifiers under an incorrect assumption.

Pattern.MULTILINE or (?m) tells Java to accept the anchors ^ and $ to match at the start and end of each line (otherwise they only match at the start/end of the entire string).

Pattern.DOTALL or (?s) tells Java to allow the dot to match newline characters, too.

Second, in your case, the regex fails because you're using the matches() method which expects the regex to match the entire string - which of course doesn't work since there are some characters left after (\\W)*(\\S)* have matched.

So if you're simply looking for a string that starts with User Comments:, use the regex

^\s*User Comments:\s*(.*)

with the Pattern.DOTALL option:

Pattern regex = Pattern.compile("^\\s*User Comments:\\s+(.*)", Pattern.DOTALL);
Matcher regexMatcher = regex.matcher(subjectString);
if (regexMatcher.find()) {
    ResultString =;

ResultString will then contain the text after User Comments:

Get escaped URL parameter

jQuery code snippet to get the dynamic variables stored in the url as parameters and store them as JavaScript variables ready for use with your scripts:

$.urlParam = function(name){
    var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(window.location.href);
    if (results==null){
       return null;
       return results[1] || 0;

$.urlParam('param1'); // name
$.urlParam('id');        // 6
$.urlParam('param2');   // null

//example params with spaces Coast
//output: Gold%20Coast

//output: Gold Coast in javascript

There's also Array.find() in ES6 which returns the first matching element it finds.

const myArray = [1, 2, 3]

const myElement = myArray.find((element) => element === 2)

// => 2

How do I add a Maven dependency in Eclipse?

Open the pom.xml file.

under the project tag add <dependencies> as another tag, and google for the Maven dependencies. I used this to search.

So after getting the dependency create another tag dependency inside <dependencies> tag.

So ultimately it will look something like this.

<project xmlns="" xmlns:xsi="" xsi:schemaLocation="">
      <!-- -->

Hope it helps.

How to find a user's home directory on linux or unix?

I assume you want to find the home directory of a DIFFERENT user. Obviously getting the "user.home" property would be the easiest way to get the current user home directory.

To get an arbitrary user home directory, it takes a bit of finesse with the command line:

String[] command = {"/bin/sh", "-c", "echo ~root"}; //substitute desired username
Process outsideProcess = rt.exec(command);
String tempResult;
StringBuilder sb = new StringBuilder();
while((tempResult = br.readLine()) != null) sb.append(tempResult);
return sb.toString().trim();

Now technically, we should have a thread waiting on the stdout and stderr so the buffers don't fill up and lock up the process, but I'd sure hope the buffer could at least hold a single username. Also, you might want to check the result to see if it starts with ~root (or whatever username you used) just to make sure the user does exist and it evaluated correctly.

Hope that helps. Vote for this answer if it does as I'm new to contributing to SO and could use the points.

C#: easiest way to populate a ListBox from a List

Is this what you are looking for:

myListBox.DataSource = MyList;

On delete cascade with doctrine2

There are two kinds of cascades in Doctrine:

1) ORM level - uses cascade={"remove"} in the association - this is a calculation that is done in the UnitOfWork and does not affect the database structure. When you remove an object, the UnitOfWork will iterate over all objects in the association and remove them.

2) Database level - uses onDelete="CASCADE" on the association's joinColumn - this will add On Delete Cascade to the foreign key column in the database:

@ORM\JoinColumn(name="father_id", referencedColumnName="id", onDelete="CASCADE")

I also want to point out that the way you have your cascade={"remove"} right now, if you delete a Child object, this cascade will remove the Parent object. Clearly not what you want.

Looping through a DataTable

If you want to change the contents of each and every cell in a datatable then we need to Create another Datatable and bind it as follows using "Import Row". If we don't create another table it will throw an Exception saying "Collection was Modified".

Consider the following code.

//New Datatable created which will have updated cells
DataTable dtUpdated = new DataTable();

//This gives similar schema to the new datatable
dtUpdated = dtReports.Clone();
foreach (DataRow row in dtReports.Rows)
    for (int i = 0; i < dtReports.Columns.Count; i++)
        string oldVal = row[i].ToString();
        string newVal = "{"+oldVal;
        row[i] = newVal;

This will have all the cells preceding with Paranthesis({)

How to draw vertical lines on a given plot in matplotlib

For multiple lines

xposition = [0.3, 0.4, 0.45]
for xc in xposition:
    plt.axvline(x=xc, color='k', linestyle='--')

What is the purpose of class methods?

I was asking myself the same question few times. And even though the guys here tried hard to explain it, IMHO the best answer (and simplest) answer I have found is the description of the Class method in the Python Documentation.

There is also reference to the Static method. And in case someone already know instance methods (which I assume), this answer might be the final piece to put it all together...

Further and deeper elaboration on this topic can be found also in the documentation: The standard type hierarchy (scroll down to Instance methods section)

Angular 2: Passing Data to Routes?

It changes in angular 2.1.0

In something.module.ts

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { BlogComponent } from './blog.component';
import { AddComponent } from './add/add.component';
import { EditComponent } from './edit/edit.component';
import { RouterModule } from '@angular/router';
import { MaterialModule } from '@angular/material';
import { FormsModule } from '@angular/forms';
const routes = [
    path: '',
    component: BlogComponent
    path: 'add',
    component: AddComponent
    path: 'edit/:id',
    component: EditComponent,
    data: {
      type: 'edit'

  imports: [
  declarations: [BlogComponent, EditComponent, AddComponent]
export class BlogModule { }

To get the data or params in edit component

import { Component, OnInit } from '@angular/core';
import { Router, ActivatedRoute, Params, Data } from '@angular/router';
  selector: 'app-edit',
  templateUrl: './edit.component.html',
  styleUrls: ['./edit.component.css']
export class EditComponent implements OnInit {
    private route: ActivatedRoute,
    private router: Router

  ) { }
  ngOnInit() {



Script parameters in Bash

I needed to make sure that my scripts are entirely portable between various machines, shells and even cygwin versions. Further, my colleagues who were the ones I had to write the scripts for, are programmers, so I ended up using this:

for ((i=1;i<=$#;i++)); 

    if [ ${!i} = "-s" ] 
    then ((i++)) 

    elif [ ${!i} = "-log" ];
    then ((i++)) 

    elif [ ${!i} = "-x" ];
    then ((i++)) 

    elif [ ${!i} = "-p" ]; 
    then ((i++)) 

    elif [ ${!i} = "-b" ];
    then ((i++)) 

    elif [ ${!i} = "-l" ];
    then ((i++)) 

    elif [ ${!i} = "-a" ];
    then ((i++)) 


Rationale: I included a script as well, since the whole operation had several steps which were quasi independent on each other (I'm saying "quasi", because even though each script could be run on its own, they were usually all run together), and in two days I found out, that about half of my colleagues, being programmers and all, were too good to be using the launcher file, follow the "usage", or read the HELP which was displayed every time they did something wrong and they were making a mess of the whole thing, running scripts with arguments in the wrong order and complaining that the scripts didn't work properly. Being the choleric I am I decided to overhaul all my scripts to make sure that they are colleague-proof. The code segment above was the first thing.

Failed to load resource under Chrome

Check the network tab to see if Chrome failed to download any resource file.

How do I clear the previous text field value after submitting the form with out refreshing the entire page?

.val() or .value is IMHO the best solution because it's useful with Ajax. And .reset() only works after page reload and APIs using Ajax never refresh pages unless it's triggered by a different script.

Inserting the iframe into react component

With ES6 you can now do it like this

Example Codepen URl to load

const iframe = '<iframe height="265" style="width: 100%;" scrolling="no" title="fx." src="//,result" frameborder="no" allowtransparency="true" allowfullscreen="true">See the Pen <a href="">fx.</a> by ycw(<a href="">@ycw</a>) on <a href="">CodePen</a>.</iframe>'; 

A function component to load Iframe

function Iframe(props) {
  return (<div dangerouslySetInnerHTML={ {__html:  props.iframe?props.iframe:""}} />);


import React from "react";
import ReactDOM from "react-dom";
function App() {
  return (
    <div className="App">
      <h1>Iframe Demo</h1>
      <Iframe iframe={iframe} />,

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

Edit on CodeSandbox:

HTML.ActionLink vs Url.Action in ASP.NET Razor

You can easily present Html.ActionLink as a button by using the appropriate CSS style. For example:

@Html.ActionLink("Save", "ActionMethod", "Controller", new { @class = "btn btn-primary" })

OR, AND Operator

I'm not sure if this answers your question, but for example:

if (A || B)

if (A && B)

Spark: Add column to dataframe conditionally

How about something like this?

val newDF = df.filter($"B" === "").take(1) match {
  case Array() => df
  case _ => df.withColumn("D", $"B" === "")

Using take(1) should have a minimal hit

Building with Lombok's @Slf4j and Intellij: Cannot find symbol log

In Intellij version 2016, 2017, enable Preferences -> Compiler -> Annotation Processors does not work for me!

The following additional checkbox helps: enter image description here

Bootstrap 3.0 Sliding Menu from left

I believe that although javascript is an option here, you have a smoother animation through forcing hardware accelerate with CSS3. You can achieve this by setting the following CSS3 properties on the moving div:

div.hardware-accelarate {
     -webkit-transform: translate3d(0,0,0);
        -moz-transform: translate3d(0,0,0);
         -ms-transform: translate3d(0,0,0);
          -o-transform: translate3d(0,0,0);
             transform: translate3d(0,0,0);

I've made a plunkr setup for ya'll to test and tweak...

How to specify the bottom border of a <tr>?

Add border-collapse:collapse to the table.



table.myTable tr{
  border:1px solid red;

This worked for me.

npm not working - "read ECONNRESET"

You may also need to specify the proxy server/port, in some environments the system settings for proxy are not enough for npm to work.

    npm config set proxy ""

Using stored procedure output parameters in C#

I slightly modified your stored procedure (to use SCOPE_IDENTITY) and it looks like this:

CREATE PROCEDURE usp_InsertContract
    @ContractNumber varchar(7),
    @NewId int OUTPUT
    INSERT INTO [dbo].[Contracts] (ContractNumber)
    VALUES (@ContractNumber)


I tried this and it works just fine (with that modified stored procedure):

// define connection and command, in using blocks to ensure disposal
using(SqlConnection conn = new SqlConnection(pvConnectionString ))
using(SqlCommand cmd = new SqlCommand("dbo.usp_InsertContract", conn))
    cmd.CommandType = CommandType.StoredProcedure;

    // set up the parameters
    cmd.Parameters.Add("@ContractNumber", SqlDbType.VarChar, 7);
    cmd.Parameters.Add("@NewId", SqlDbType.Int).Direction = ParameterDirection.Output;

    // set parameter values
    cmd.Parameters["@ContractNumber"].Value = contractNumber;

    // open connection and execute stored procedure

    // read output value from @NewId
    int contractID = Convert.ToInt32(cmd.Parameters["@NewId"].Value);

Does this work in your environment, too? I can't say why your original code won't work - but when I do this here, VS2010 and SQL Server 2008 R2, it just works flawlessly....

If you don't get back a value - then I suspect your table Contracts might not really have a column with the IDENTITY property on it.

RuntimeError: module compiled against API version a but this version of numpy is 9

You are likely running the Mac default (/usr/bin/python) which has an older version of numpy installed in the system folders. The easiest way to get python working with opencv is to use brew to install both python and opencv into /usr/local and run the /usr/local/bin/python.

brew install python
brew tap homebrew/science
brew install opencv

How to get Current Directory?

Why does nobody here consider using this simple code?

TCHAR szDir[MAX_PATH] = { 0 };

GetModuleFileName(NULL, szDir, MAX_PATH);
szDir[std::string(szDir).find_last_of("\\/")] = 0;

or even simpler

TCHAR szDir[MAX_PATH] = { 0 };
TCHAR* szEnd = nullptr;
GetModuleFileName(NULL, szDir, MAX_PATH);
szEnd = _tcsrchr(szDir, '\\');
*szEnd = 0;

jQuery $.ajax(), $.post sending "OPTIONS" as REQUEST_METHOD in Firefox

I had a similar problem with trying to use the Facebook API.

The only contentType which didn't send the Preflighted request seemed to be just text/plain... not the rest of the parameters mentioned at mozilla here

  • Why is this the only browser which does this?
  • Why doesn't Facebook know and accept the preflight request?

FYI: The aforementioned Moz doc suggests X-Lori headers should trigger a Preflighted request ... it doesn't.

Removing all empty elements from a hash / YAML?

Here is something I have:

# recursively remove empty keys (hashes), values (array), hashes and arrays from hash or array
def sanitize data
  case data
  when Array
    data.delete_if { |value| res = sanitize(value); res.blank? }
  when Hash
    data.delete_if { |_, value| res = sanitize(value); res.blank? }
  data.blank? ? nil : data

What do 1.#INF00, -1.#IND00 and -1.#IND mean?

For those of you in a .NET environment the following can be a handy way to filter non-numbers out (this example is in VB.NET, but it's probably similar in C#):

If Double.IsNaN(MyVariableName) Then
    MyVariableName = 0 ' Or whatever you want to do here to "correct" the situation
End If

If you try to use a variable that has a NaN value you will get the following error:

Value was either too large or too small for a Decimal.

How to get full width in body element

If its in a landscape then you will be needing more width and less height! That's just what all websites have.

Lets go with a basic first then the rest!

The basic CSS:

By CSS you can do this,

#body {
width: 100%;
height: 100%;

Here you are using a div with id body, as:

  <div id="body>
    all the text would go here!

Then you can have a web page with 100% height and width.

What if he tries to resize the window?

The issues pops up, what if he tries to resize the window? Then all the elements inside #body would try to mess up the UI. For that you can write this:

#body {
height: 100%;
width: 100%;

And just add min-height max-height min-width and max-width.

This way, the page element would stay at the place they were at the page load.

Using JavaScript:

Using JavaScript, you can control the UI, use jQuery as:

$('#body').css('min-height', '100%');

And all other remaining CSS properties, and JS will take care of the User Interface when the user is trying to resize the window.

How to not add scroll to the web page:

If you are not trying to add a scroll, then you can use this JS

$('#body').css('min-height', screen.height); // or anyother like window.height

This way, the document will get a new height whenever the user would load the page.

Second option is better, because when users would have different screen resolutions they would want a CSS or Style sheet created for their own screen. Not for others!

Tip: So try using JS to find current Screen size and edit the page! :)

Open new popup window without address bars in firefox & IE

check this if it works it works fine for me

  var windowObjectReference;
  var strWindowFeatures = "menubar=no,location=no,resizable=no,scrollbars=no,status=yes,width=400,height=350";

     function openRequestedPopup() {
      windowObjectReference ="", "CNN_WindowName", strWindowFeatures);

Mask output of `The following objects are masked from....:` after calling attach() function

It may be "better" to not use attach at all. On the plus side, you can save some typing if you use attach. Let's say your dataset is called mydata and you have variables called v1, v2, and v3. If you don't attach mydata, then you will type mean(mydata$v1) to get the mean of v1. If you do attach mydata, then you will type mean(v1) to get the mean of v1. But, if you don't detach the mydata dataset (every time), you'll get the message about the objects being masked going forward.

Solution 1 (assuming you want to attach):

  1. Use detach every time.
  2. See Dan Tarr's response if you already have the data attached (and it may be in the global environment several times). Then, in the future, use detach every time.

Solution 2

Don't use attach. Instead, include the dataset name every time you refer to a variable. The form is mydata$v1 (name of data set, dollar sign, name of variable).

As for me, I used solution 1 a lot in the past, but I've moved to solution 2. It's a bit more typing in the beginning, but if you are going to use the code multiple times, it just seems cleaner.

Should try...catch go inside or outside a loop?

As long as you are aware of what you need to accomplish in the loop you could put the try catch outside the loop. But it is important to understand that the loop will then end as soon as the exception occurs and that may not always be what you want. This is actually a very common error in Java based software. People need to process a number of items, such as emptying a queue, and falsely rely on an outer try/catch statement handling all possible exceptions. They could also be handling only a specific exception inside the loop and not expect any other exception to occur. Then if an exception occurs that is not handled inside the loop then the loop will be "preemted", it ends possibly prematurely and the outer catch statement handles the exception.

If the loop had as its role in life to empty a queue then that loop very likely could end before that queue was really emptied. Very common fault.

Set CSS property in Javascript?

<h1>Silence and Smile</h1>
<input  type="button"  value="Show Red"   onclick="document.getElementById('h1').style.color='Red'"/>
<input  type="button"  value="Show Green" onclick="document.getElementById('h1').style.color='Green'"/>

MySQL: Get column name or alias from query

I think this should do what you need (builds on the answer above) . I am sure theres a more pythony way to write it, but you should get the general idea.

columns = cursor.description
result = []
for value in cursor.fetchall():
    tmp = {}
    for (index,column) in enumerate(value):
        tmp[columns[index][0]] = column

In HTML5, should the main navigation be inside or outside the <header> element?

It's completely up to you. You can either put them in the header or not, as long as the elements within them are internal navigation elements only (i.e. don't link to external sites such as a twitter or facebook account) then it's fine.

They tend to get placed in a header simply because that's where navigation often goes, but it's not set in stone.

You can read more about it at HTML5 Doctor.

Understanding the Rails Authenticity Token

Methods Where authenticity_token is required

authenticity_token is required in case of idempotent methods like post, put and delete, Because Idempotent methods are affecting to data.

Why It is Required

It is required to prevent from evil actions. authenticity_token is stored in session, whenever a form is created on web pages for creating or updating to resources then a authenticity token is stored in hidden field and it sent with form on server. Before executing action user sent authenticity_token is cross checked with authenticity_token stored in session. If authenticity_token is same then process is continue otherwise it does not perform actions.

PHP-FPM and Nginx: 502 Bad Gateway

If anyone finds this page by encountering the same problem I had, I found the answer here.

For those of you who can't be bothered to click and work it out for themselves... ;)

The Condition:

Ubuntu or Debian server with NGINX and PHP 5.3 works fine but upgrading PHP to 5.4 gives 502 Bad Gateway errors. Looking for services running on port 9000 (typically running netstat -lp or similar) returns nothing.

The fix:

Open /etc/php5/fpm/pool.d/www.conf and make a note of the 'listen' parameter (in my case /var/run/php5-fpm.sock):

; The address on which to accept FastCGI requests.
; Valid syntaxes are:
;   ''    - to listen on a TCP socket to a specific address on
;                            a specific port;
;   'port'                 - to listen on a TCP socket to all addresses on a
;                            specific port;
;   '/path/to/unix/socket' - to listen on a unix socket.
; Note: This value is mandatory.
listen = /var/run/php5-fpm.sock

and replace the fastcgi_pass variable in your vhost with the location you just noted.

So this sample symfony2 configuration (taken from here):

  # pass the PHP scripts to FastCGI server listening on
  location ~ ^/(app|app_dev)\.php(/|$) {
    fastcgi_split_path_info ^(.+\.php)(/.*)$;
    include fastcgi_params;
    fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
    fastcgi_param  HTTPS              off;

becomes this:

  # pass the PHP scripts to FastCGI server at /var/run/php5-fpm.sock
  location ~ ^/(app|app_dev)\.php(/|$) {
    fastcgi_pass unix:/var/run/php5-fpm.sock;
    fastcgi_split_path_info ^(.+\.php)(/.*)$;
    include fastcgi_params;
    fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
    fastcgi_param  HTTPS              off;

Then restart nginx:

sudo /etc/init.d/nginx restart

Note: replace ~ ^/(app|app_dev)\.php(/|$) { with ~ ^/index\.php(/|$) { if you're not on SF2**

Hope this saves someone a little bit of time :)


Of course, you could change the listen = /var/run/php5-fpm.sock to listen = in /etc/php5/fpm/pool.d/www.conf then restart php5-fpm (which would save you from having to change your vhosts), but you have to assume they changed php5-fpm to run through a socket rather than listening on port 9000 for a reason.


If you're still experiencing 502 error see this answer.

ERROR Could not load file or assembly 'AjaxControlToolkit' or one of its dependencies

Just Add AjaxControlToolkit.dll to your Reference folder.

On your Project Solution

Right Click on Reference Folder  > Add Reference > browse  AjaxControlToolkit.dll .

Then build.


Differences between Html.TextboxFor and Html.EditorFor in MVC and Razor

The advantages of EditorFor is that your code is not tied to an <input type="text". So if you decide to change something to the aspect of how your textboxes are rendered like wrapping them in a div you could simply write a custom editor template (~/Views/Shared/EditorTemplates/string.cshtml) and all your textboxes in your application will automatically benefit from this change whereas if you have hardcoded Html.TextBoxFor you will have to modify it everywhere. You could also use Data Annotations to control the way this is rendered.

How to start Apache and MySQL automatically when Windows 8 comes up

Copy xampp_start.exe from your XAMPP install directory to C:\Users\YOUR USERNAME\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup.

Replace YOUR USERNAME with your username.

Git: How to squash all commits on branch

Another simple way to do this: go on the origin branch and do a merge --squash. This command doesn't do the "squashed" commit. when you do it, all commit messages of yourBranch will be gathered.

$ git checkout master
$ git merge --squash yourBranch
$ git commit # all commit messages of yourBranch in one, really useful
 > [status 5007e77] Squashed commit of the following: ...

How does one convert a HashMap to a List in Java?

Collection Interface has 3 views

  • keySet
  • values
  • entrySet

Other have answered to to convert Hashmap into two lists of key and value. Its perfectly correct

My addition: How to convert "key-value pair" (aka entrySet)into list.

      Map m=new HashMap();
          m.put(3, "dev2");
          m.put(4, "dev3");

      List<Entry> entryList = new ArrayList<Entry>(m.entrySet());

      for (Entry s : entryList) {

ArrayList has this constructor.

Compare data of two Excel Columns A & B, and show data of Column A that do not exist in B

All values of column A that are not present in column B will have a red background. Hope that it helps as starting point.

Sub highlight_missings()
Dim i As Long, lastA As Long, lastB As Long
Dim compare As Variant
lastA = Range("A65536").End(xlUp).Row
lastB = Range("B65536").End(xlUp).Row

For i = 2 To lastA
    compare = Application.Match(Range("a" & i), Range("B2:B" & lastB), 0)
        If IsError(compare) Then
            Range("A" & i).Interior.ColorIndex = 3
        End If
Next i
End Sub