Programs & Examples On #Parsecontrol

ParseControl is an ASP.NET function that parses an input string to create an ASP.NET server control object.

How do I change the color of radio buttons?

As other said, there's no way to achieve this in all browser, so best way of doing so crossbrowser is using javascript unobtrusively. Basically you have to turn your radiobutton into links (fully customizable via CSS). each click on link will be bound to the related radiobox, toggling his state and all the others.

Display HTML form values in same page after submit using Ajax

<script type = "text/javascript">
function get_values(input_id)
var input = document.getElementById(input_id).value;

<!--Insert more code here-->

<input type = "text" id = "textfield">
<input type = "button" onclick = "get('textfield')" value = "submit">

Next time you ask a question here, include more detail and what you have tried.

Xcode 4: create IPA file instead of .xcarchive

Same issue. I solved setting the "skip install" flag to YES for each external projects, leaving the other targets of the main project unchanged.

I also had to go to "Edit scheme…", choose the "Archiving" panel and set the correct build setting for my ad-hoc purpose.

Then a simple Product -> Archive -> Share made the expected job.

How to toggle boolean state of react component?

Since nobody posted this, I am posting the correct answer. If your new state update depends on the previous state, always use the functional form of setState which accepts as argument a function that returns a new state.

In your case:

this.setState(prevState => ({
  check: !prevState.check

See docs

Since this answer is becoming popular, adding the approach that should be used for React Hooks (v16.8+):

If you are using the useState hook, then use the following code (in case your new state depends on the previous state):

const [check, setCheck] = useState(false);
// ...
setCheck(prevCheck => !prevCheck);

Convert a string to a datetime

Nobody mentioned this, but in some cases the other method fails to recognize the datetime...

You can try this instead, which will convert the specified string representation of a date and time to an equivalent date and time value

string iDate = "05/05/2005";
DateTime oDate = Convert.ToDateTime(iDate);
MessageBox.Show(oDate.Day + " " + oDate.Month + "  " + oDate.Year );

What's the best way to set a single pixel in an HTML5 canvas?

To complete Phrogz very thorough answer, there is a critical difference between fillRect() and putImageData().
The first uses context to draw over by adding a rectangle (NOT a pixel), using the fillStyle alpha value AND the context globalAlpha and the transformation matrix, line caps etc..
The second replaces an entire set of pixels (maybe one, but why ?)
The result is different as you can see on jsperf.

Nobody wants to set one pixel at a time (meaning drawing it on screen). That is why there is no specific API to do that (and rightly so).
Performance wise, if the goal is to generate a picture (for example a ray-tracing software), you always want to use an array obtained by getImageData() which is an optimized Uint8Array. Then you call putImageData() ONCE or a few times per second using setTimeout/seTInterval.

Android: How to Programmatically set the size of a Layout

LinearLayout YOUR_LinearLayout =(LinearLayout)findViewById(
    LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(
                       /*width*/ ViewGroup.LayoutParams.MATCH_PARENT,
               /*height*/ 100,
               /*weight*/ 1.0f

How to reload a page using JavaScript


See this MDN page for more information.

If you are refreshing after an onclick then you'll need to return false directly after

return false;

Bizarre Error in Chrome Developer Console - Failed to load resource: net::ERR_CACHE_MISS

See if you can recreate the issue in an Incognito tab. If you find that the problem no longer occurs then I would recommend you go through your extensions, perhaps disabling them one at a time. This is commonly the cause as touched on by Nikola

PL/SQL, how to escape single quote in a string?

You can use literal quoting:

stmt := q'[insert into MY_TBL (Col) values('ER0002')]';

Documentation for literals can be found here.

Alternatively, you can use two quotes to denote a single quote:

stmt := 'insert into MY_TBL (Col) values(''ER0002'')';

The literal quoting mechanism with the Q syntax is more flexible and readable, IMO.

Meaning of Open hashing and Closed hashing

The use of "closed" vs. "open" reflects whether or not we are locked in to using a certain position or data structure (this is an extremely vague description, but hopefully the rest helps).

For instance, the "open" in "open addressing" tells us the index (aka. address) at which an object will be stored in the hash table is not completely determined by its hash code. Instead, the index may vary depending on what's already in the hash table.

The "closed" in "closed hashing" refers to the fact that we never leave the hash table; every object is stored directly at an index in the hash table's internal array. Note that this is only possible by using some sort of open addressing strategy. This explains why "closed hashing" and "open addressing" are synonyms.

Contrast this with open hashing - in this strategy, none of the objects are actually stored in the hash table's array; instead once an object is hashed, it is stored in a list which is separate from the hash table's internal array. "open" refers to the freedom we get by leaving the hash table, and using a separate list. By the way, "separate list" hints at why open hashing is also known as "separate chaining".

In short, "closed" always refers to some sort of strict guarantee, like when we guarantee that objects are always stored directly within the hash table (closed hashing). Then, the opposite of "closed" is "open", so if you don't have such guarantees, the strategy is considered "open".

PHP function overloading

You cannot overload PHP functions. Function signatures are based only on their names and do not include argument lists, so you cannot have two functions with the same name. Class method overloading is different in PHP than in many other languages. PHP uses the same word but it describes a different pattern.

You can, however, declare a variadic function that takes in a variable number of arguments. You would use func_num_args() and func_get_arg() to get the arguments passed, and use them normally.

For example:

function myFunc() {
    for ($i = 0; $i < func_num_args(); $i++) {
        printf("Argument %d: %s\n", $i, func_get_arg($i));

Argument 0: a
Argument 1: 2
Argument 2: 3.5
myFunc('a', 2, 3.5);

Usage of $broadcast(), $emit() And $on() in AngularJS

This little example shows how the $rootScope emit a event that will be listen by a children scope in another controller.



  .controller('ExampleController1', Controller1);

Controller1.$inject = ['$rootScope'];

function Controller1($rootScope) {
  var vm = this, 
      message = 'Hi my children scope boy';

  vm.sayHi = sayHi;

  function sayHi(){
    $rootScope.$broadcast('greeting', message);


  .controller('ExampleController2', Controller2);

Controller2.$inject = ['$scope'];

function Controller2($scope) {
  var vm = this;

  $scope.$on('greeting', listenGreeting)

  function listenGreeting($event, message){
    alert(['Message received',message].join(' : '));



The answer of @gayathri bottom explain technically the differences of all those methods in the scope angular concept and their implementations $scope and $rootScope.

How to load/edit/run/save text files (.py) into an IPython notebook cell?

EDIT: Starting from IPython 3 (now Jupyter project), the notebook has a text editor that can be used as a more convenient alternative to load/edit/save text files.

A text file can be loaded in a notebook cell with the magic command %load.

If you execute a cell containing:


the content of will be loaded in the next cell. You can edit and execute it as usual.

To save the cell content back into a file add the cell-magic %%writefile at the beginning of the cell and run it. Beware that if a file with the same name already exists it will be silently overwritten.

To see the help for any magic command add a ?: like %load? or %%writefile?.

For general help on magic functions type "%magic" For a list of the available magic functions, use %lsmagic. For a description of any of them, type %magic_name?, e.g. '%cd?'.

See also: Magic functions from the official IPython docs.

Why am I getting "Thread was being aborted" in ASP.NET?

If you spawn threads in Application_Start, they will still be executing in the application pool's AppDomain.

If an application is idle for some time (meaning that no requests are coming in), or certain other conditions are met, ASP.NET will recycle the entire AppDomain.

When that happens, any threads that you started from that AppDomain, including those from Application_Start, will be aborted.

Lots more on application pools and recycling in this question: What exactly is Appdomain recycling

If you are trying to run a long-running process within IIS/ASP.NET, the short answer is usually "Don't". That's what Windows Services are for.

What is the purpose of the var keyword and when should I use it (or omit it)?

Inside a code you if you use a variable without using var, then what happens is the automatically var var_name is placed in the global scope eg:

someFunction() {
    var a = some_value; /*a has local scope and it cannot be accessed when this
    function is not active*/
    b = a; /*here it places "var b" at top of script i.e. gives b global scope or
    uses already defined global variable b */

How to create a new column in a select query

SELECT field1, 
       'example' AS newfield

This will add a column called "newfield" to the output, and its value will always be "example".

How to find the files that are created in the last hour in unix

find ./ -cTime -1 -type f


find ./ -cmin -60 -type f

Download file from web in Python 3

You can use wget which is popular downloading shell tool for that. This will be the simplest method since it does not need to open up the destination file. Here is an example.

import wget
url = '', '/Users/scott/Downloads/cat4.jpg') 

How to check if a string is null in python

Try this:

if cookie and not cookie.isspace():
    # the string is non-empty
    # the string is empty

The above takes in consideration the cases where the string is None or a sequence of white spaces.

How can I autoformat/indent C code in vim?

The builtin command for properly indenting the code has already been mentioned (gg=G). If you want to beautify the code, you'll need to use an external application like indent. Since % denotes the current file in ex mode, you can use it like this:

:!indent %

How to make a checkbox checked with jQuery?

$('#test').prop('checked', true);

Note only in jQuery 1.6+

Create numpy matrix filled with NaNs

You rarely need loops for vector operations in numpy. You can create an uninitialized array and assign to all entries at once:

>>> a = numpy.empty((3,3,))
>>> a[:] = numpy.nan
>>> a
array([[ NaN,  NaN,  NaN],
       [ NaN,  NaN,  NaN],
       [ NaN,  NaN,  NaN]])

I have timed the alternatives a[:] = numpy.nan here and a.fill(numpy.nan) as posted by Blaenk:

$ python -mtimeit "import numpy as np; a = np.empty((100,100));" "a.fill(np.nan)"
10000 loops, best of 3: 54.3 usec per loop
$ python -mtimeit "import numpy as np; a = np.empty((100,100));" "a[:] = np.nan" 
10000 loops, best of 3: 88.8 usec per loop

The timings show a preference for ndarray.fill(..) as the faster alternative. OTOH, I like numpy's convenience implementation where you can assign values to whole slices at the time, the code's intention is very clear.

Note that ndarray.fill performs its operation in-place, so numpy.empty((3,3,)).fill(numpy.nan) will instead return None.

How can I access Google Sheet spreadsheets only with Javascript?

Sorry, this is a lousy answer. Apparently this has been an issue for almost two years so don't hold your breath.

Here is the official request that you can "star"

Probably the closest you can come is rolling your own service with Google App Engine/Python and exposing whatever subset you need with your own JS library. Though I'd love to have a better solution myself.

How to find all duplicate from a List<string>?

If you're looking for a more generic method:

public static List<U> FindDuplicates<T, U>(this List<T> list, Func<T, U> keySelector)
        return list.GroupBy(keySelector)
            .Where(group => group.Count() > 1)
            .Select(group => group.Key).ToList();

EDIT: Here's an example:

public class Person {
    public string Name {get;set;}
    public int Age {get;set;}

List<Person> list = new List<Person>() { new Person() { Name = "John", Age = 22 }, new Person() { Name = "John", Age = 30 }, new Person() { Name = "Jack", Age = 30 } };

var duplicateNames = list.FindDuplicates(p => p.Name);
var duplicateAges = list.FindDuplicates(p => p.Age);

foreach(var dupName in duplicateNames) {
    Console.WriteLine(dupName); // Will print out John

foreach(var dupAge in duplicateAges) {
    Console.WriteLine(dupAge); // Will print out 30

Best way to resolve file path too long exception

Not mention so far and an update, there is a very well establish library for handling paths that are too long. AlphaFS is a .NET library providing more complete Win32 file system functionality to the .NET platform than the standard System.IO classes. The most notable deficiency of the standard .NET System.IO is the lack of support of advanced NTFS features, most notably extended length path support (eg. file/directory paths longer than 260 characters).

Select a Column in SQL not in Group By

Thing I like to do is to wrap addition columns in aggregate function, like max(). It works very good when you don't expect duplicate values.

Select MAX(cpe.createdon) As MaxDate, cpe.fmgcms_cpeclaimid, MAX(cpe.fmgcms_claimid) As fmgcms_claimid 
from Filteredfmgcms_claimpaymentestimate cpe
where cpe.createdon < 'reportstartdate'
group by cpe.fmgcms_cpeclaimid

What is the correct Performance Counter to get CPU and Memory Usage of a Process?

From this post:

To get the entire PC CPU and Memory usage:

using System.Diagnostics;

Then declare globally:

private PerformanceCounter theCPUCounter = 
   new PerformanceCounter("Processor", "% Processor Time", "_Total"); 

Then to get the CPU time, simply call the NextValue() method:


This will get you the CPU usage

As for memory usage, same thing applies I believe:

private PerformanceCounter theMemCounter = 
   new PerformanceCounter("Memory", "Available MBytes");

Then to get the memory usage, simply call the NextValue() method:


For a specific process CPU and Memory usage:

private PerformanceCounter theCPUCounter = 
   new PerformanceCounter("Process", "% Processor Time",              

where Process.GetCurrentProcess().ProcessName is the process name you wish to get the information about.

private PerformanceCounter theMemCounter = 
   new PerformanceCounter("Process", "Working Set",

where Process.GetCurrentProcess().ProcessName is the process name you wish to get the information about.

Note that Working Set may not be sufficient in its own right to determine the process' memory footprint -- see What is private bytes, virtual bytes, working set?

To retrieve all Categories, see Walkthrough: Retrieving Categories and Counters

The difference between Processor\% Processor Time and Process\% Processor Time is Processor is from the PC itself and Process is per individual process. So the processor time of the processor would be usage on the PC. Processor time of a process would be the specified processes usage. For full description of category names: Performance Monitor Counters

An alternative to using the Performance Counter

Use System.Diagnostics.Process.TotalProcessorTime and System.Diagnostics.ProcessThread.TotalProcessorTime properties to calculate your processor usage as this article describes.

How to determine previous page URL in Angular?

This worked for me in angular >= 6.x versions:
            .subscribe((event) => {
              if (event instanceof NavigationStart) {
                window.localStorage.setItem('previousUrl', this.router.url);

how to set length of an column in hibernate with maximum length

Use @Column annotation and define its length attribute. Check Hibernate's documentation for references (section

How to create a timer using tkinter?

I just created a simple timer using the MVP pattern (however it may be overkill for that simple project). It has quit, start/pause and a stop button. Time is displayed in HH:MM:SS format. Time counting is implemented using a thread that is running several times a second and the difference between the time the timer has started and the current time.

Source code on github

Abstraction VS Information Hiding VS Encapsulation

Encapsulation: binding the data members and member functions together is called encapsulation. encapsulation is done through class. abstraction: hiding the implementation details form usage or from view is called abstraction. ex: int x; we don't know how int will internally work. but we know int will work. that is abstraction.

php how to go one level up on dirname(__FILE__)

To Whom, deailing with share hosting environment and still chance to have Current PHP less than 7.0 Who does not have dirname( __FILE__, 2 ); it is possible to use following.

function dirname_safe($path, $level = 0){
    $dir = explode(DIRECTORY_SEPARATOR, $path);
    $level = $level * -1;
    if($level == 0) $level = count($dir);
    array_splice($dir, $level);

print_r(dirname_safe(__DIR__, 2));

Want to show/hide div based on dropdown box selection

try this which is working for me in my test demo

//  var selectedValue = parseInt(jQuery(this).val());
var text = $('#dropdown').val();
    //Depend on Value i.e. 0 or 1 respective function gets called. 
        case 'Reporting':
          // alert("hello1");
        case 'Buyer':
            alert("catch default");


How to create <input type=“text”/> dynamically

The core idea of the solution is:

  • create a new input element
  • Add the type text
  • append the element to the DOM

This can be done via this simple script:

var input = document.createElement('input');
input.setAttribute('type', 'text');

Now the question is, how to render this process dynamic. As stated in the question, there is another input where the user insert the number of input to generate. This can be done as follows:

function renderInputs(el){
  var n = el.value && parseInt(el.value, 10);
  var input;
  var parent = document.getElementById("parent");
  for(var i=0; i<n; i++){
    input = document.createElement('input');
    input.setAttribute('type', 'text');

function cleanDiv(div){
  div.innerHTML = '';
Insert number of input to generate: </br>
<input type="text" onchange="renderInputs(this)"/>

<div id="parent">
Generated inputs:

but usually adding just an input is not really usefull, it would be better to add a name to the input, so that it can be easily sent as a form. This snippet add also a name:

function renderInputs(el){
  var n = el.value;
  var input, label;
  var parent = document.getElementById("parent");
    input = document.createElement('input');
    input.setAttribute('type', 'text');
    input.setAttribute('name', name);
    label = document.createElement('label');
    label.setAttribute('for', name);
    label.innerText = name;

function cleanDiv(div){
  div.innerHTML = '';
Insert the names, separated by comma, of the inputs to generate: </br>
<input type="text" onchange="renderInputs(this)"/>
Generated inputs: </br>
<div id="parent">


SqlException from Entity Framework - New transaction is not allowed because there are other threads running in the session

I am a little bit late, but I had this error too. I solved the problem by checking what where the values that where updating.

I found out that my query was wrong and that there where over 250+ edits pending. So I corrected my query, and now it works correct.

So in my situation: Check the query for errors, by debugging over the result that the query returns. After that correct the query.

Hope this helps resolving future problems.

Xamarin.Forms ListView: Set the highlight color of a tapped item

It looks like there is actually a cross-platform way to do this that works on both iOS and Android (not sure about Windows). It uses only binding and does not require custom renderers (which seems rare). This is a mash-up of lots of googling, so thanks to anyone who I may have borrowed from...

I am assuming ViewCells, but this should work for Text or Image cells as well. I am only including the relevant code here beyond the typical text, image, etc.

On your page do something like this:

MyModel model1 = new MyModel();
MyModel model2 = new MyModel();

ListView list = new ListView
    ItemsSource = new List<MyModel> { model1, model2 };
    ItemTemplate = new DataTemplate( typeof(MyCell) )

Your custom Model might look something like this:

public class MyModel : INotifyPropertyChanged
    public event PropertyChangedEventHandler PropertyChanged;

    private Color _backgroundColor;

    public Color BackgroundColor 
        get { return _backgroundColor; } 
            _backgroundColor = value; 

            if ( PropertyChanged != null )
                PropertyChanged( this, new PropertyChangedEventArgs( "BackgroundColor" ) );

    public void SetColors( bool isSelected )
        if ( isSelected )
            BackgroundColor = Color.FromRgb( 0.20, 0.20, 1.0 );
            BackgroundColor = Color.FromRgb( 0.95, 0.95, 0.95 ); 

Then for your ItemTemplate you need a custom cell class something like this:

public class MyCell : ViewCell
    public MyCell() : base()
        RelativeLayout layout = new RelativeLayout();
        layout.SetBinding( Layout.BackgroundColorProperty, new Binding( "BackgroundColor" ) );

        View = layout;

Then in your ItemSelected event handler, do the following. Note that 'selected' is an instance of MyModel used to track the currently selected item. I am only showing background color here, but I also use this technique to reverse highlight the text and detail text colors.

private void ItemSelected( object sender, ItemTappedEventArgs args )
    // Deselect previous
    if ( selected != null )
        selected.SetColors( false );

    // Select new
    selected = (list.SelectedItem as MyModel);
    selected.SetColors( true );

Apply function to each column in a data frame observing each columns existing data type

A solution using retype() from hablar to coerce factors to character or numeric type depending on feasability. I'd use dplyr for applying max to each column.



# Retype() simplifies each columns type, e.g. always removes factors
d <- d %>% retype()

# Check max for each column
d %>% summarise_all(max)


Not the new column types.

     v1 v2       v3 v4   
  <dbl> <chr> <dbl> <chr>
1 0.974 j      1.09 J   


# Sample data borrowed from @joran
d <- data.frame(v1 = runif(10), v2 = letters[1:10], 
                v3 = rnorm(10), v4 = LETTERS[1:10],stringsAsFactors = TRUE)

How do we count rows using older versions of Hibernate (~2009)?

If you are using Hibernate 5+, then query will be modified as

Long count = session.createQuery("select count(1) from  Book")

Or if you Need TypedQuery

Long count = session.createQuery("select count(1) from  Book",Long.class)

How to use the PI constant in C++

I would do

template<typename T>
T const pi = std::acos(-T(1));


template<typename T>
T const pi = std::arg(-std::log(T(2)));

I would not typing in p to the precision you need. What is that even supposed to mean? The precision you need is the precision of T, but we know nothing about T.

You might say: What are you talking about? T will be float, double or long double. So, just type in the precision of long double, i.e.

template<typename T>
T const pi = static_cast<T>(/* long double precision p */);

But do you really know that there won't be a new floating point type in the standard in the future with an even higher precision than long double? You don't.

And that's why the first solution is beautiful. You can be quite sure that the standard would overload the trigonometric functions for a new type.

And please, don't say that the evaluation of a trigonometric function at initialization is a performance penalty.

How does the Spring @ResponseBody annotation work?

The first basic thing to understand is the difference in architectures.

One end you have the MVC architecture, which is based on your normal web app, using web pages, and the browser makes a request for a page:

Browser <---> Controller <---> Model
               |      |

The browser makes a request, the controller (@Controller) gets the model (@Entity), and creates the view (JSP) from the model and the view is returned back to the client. This is the basic web app architecture.

On the other end, you have a RESTful architecture. In this case, there is no View. The Controller only sends back the model (or resource representation, in more RESTful terms). The client can be a JavaScript application, a Java server application, any application in which we expose our REST API to. With this architecture, the client decides what to do with this model. Take for instance Twitter. Twitter as the Web (REST) API, that allows our applications to use its API to get such things as status updates, so that we can use it to put that data in our application. That data will come in some format like JSON.

That being said, when working with Spring MVC, it was first built to handle the basic web application architecture. There are may different method signature flavors that allow a view to be produced from our methods. The method could return a ModelAndView where we explicitly create it, or there are implicit ways where we can return some arbitrary object that gets set into model attributes. But either way, somewhere along the request-response cycle, there will be a view produced.

But when we use @ResponseBody, we are saying that we do not want a view produced. We just want to send the return object as the body, in whatever format we specify. We wouldn't want it to be a serialized Java object (though possible). So yes, it needs to be converted to some other common type (this type is normally dealt with through content negotiation - see link below). Honestly, I don't work much with Spring, though I dabble with it here and there. Normally, I use

@RequestMapping(..., produces = MediaType.APPLICATION_JSON_VALUE)

to set the content type, but maybe JSON is the default. Don't quote me, but if you are getting JSON, and you haven't specified the produces, then maybe it is the default. JSON is not the only format. For instance, the above could easily be sent in XML, but you would need to have the produces to MediaType.APPLICATION_XML_VALUE and I believe you need to configure the HttpMessageConverter for JAXB. As for the JSON MappingJacksonHttpMessageConverter configured, when we have Jackson on the classpath.

I would take some time to learn about Content Negotiation. It's a very important part of REST. It'll help you learn about the different response formats and how to map them to your methods.

READ_EXTERNAL_STORAGE permission for Android

I also had a similar error log and here's what I did-

  1. In onCreate method we request a Dialog Box for checking permissions

    new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},1);
  2. Method to check for the result

    public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case 1: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                // permission granted and now can proceed
             mymethod(); //a sample method called
            } else {
                // permission denied, boo! Disable the
                // functionality that depends on this permission.
                Toast.makeText(MainActivity.this, "Permission denied to read your External storage", Toast.LENGTH_SHORT).show();
        // add other cases for more permissions

The official documentation to Requesting Runtime Permissions

Inserting data to table (mysqli insert)

Okay, of course the question has been answered, but no-one seems to notice the third line of your code. It continuosly bugged me.

    mysql_select_db("web_table") or die(mysql_error());

for some reason, you made a mysqli connection to server, but you are trying to make a mysql connection to database.To get going, rather use

       $link = mysqli_connect("localhost","root","","web_table");
       mysqli_select_db ($link , "web_table" ) or die.....

or for where i began

     <?php $connection = mysqli_connect("localhost","root","","web_table");       
      global $connection; // global connection to databases - kill it once you're done

or just query with a $connection parameter as the other argument like above. Get rid of that third line.

handling DATETIME values 0000-00-00 00:00:00 in JDBC

Alternative answer, you can use this JDBC URL directly in your datasource configuration:



Source: MySQL Manual

Datetimes with all-zero components (0000-00-00 ...) — These values can not be represented reliably in Java. Connector/J 3.0.x always converted them to NULL when being read from a ResultSet.

Connector/J 3.1 throws an exception by default when these values are encountered as this is the most correct behavior according to the JDBC and SQL standards. This behavior can be modified using the zeroDateTimeBehavior configuration property. The allowable values are:

  • exception (the default), which throws an SQLException with an SQLState of S1009.
  • convertToNull, which returns NULL instead of the date.
  • round, which rounds the date to the nearest closest value which is 0001-01-01.

Update: Alexander reported a bug affecting mysql-connector-5.1.15 on that feature. See CHANGELOGS on the official website.

Passing a string with spaces as a function argument in bash

Your definition of myFunction is wrong. It should be:

    # same as before


function myFunction
    # same as before

Anyway, it looks fine and works fine for me on Bash 3.2.48.

How to print something when running Puppet client?

You could go a step further and break into the puppet code using a breakpoint.

This would only work with puppet apply or using a rspec test. Or you can manually type your code into the debugger console. Note: puppet still needs to know where your module code is at if you haven't set already.

gem install puppet puppet-debugger 
puppet module install nwops/debug
cat > test.pp <<'EOF'
$var1 = 'test'

Should show something like.

puppet apply test.pp
From file: test.pp
     1: $var1 = 'test'
     2: # add 'debug::break()' where you want to stop in your code
  => 3: debug::break()
1:>> $var1
=> "test"

Initialise a list to a specific length in Python

In a talk about core containers internals in Python at PyCon 2012, Raymond Hettinger is suggesting to use [None] * n to pre-allocate the length you want.

Slides available as PPT or via Google

The whole slide deck is quite interesting. The presentation is available on YouTube, but it doesn't add much to the slides.

How do I manage MongoDB connections in a Node.js web application? -> new project -> new cluster -> new collection -> connect -> IP address: & db cred -> connect your application -> copy connection string and paste in .env file of your node app and make sure to replace "" with the actual password for the user and also replace "/test" with your db name

create new file .env

CONNECTIONSTRING=x --> const client = new MongoClient(CONNECTIONSTRING) 

Video 100% width and height

I use JavaScript and CSS to accomplish this. The JS function needs to be called once on init and on window resize. Just tested in Chrome.


<video width="1920" height="1080" controls>
    <source src="./assets/video.mp4" type="video/mp4">
    Your browser does not support the video tag.


function scaleVideo() {
    var vid = document.getElementsByTagName('video')[0];
    var w = window.innerWidth;
    var h = window.innerHeight;

    if (w/16 >= h/9) {
        vid.setAttribute('width', w);
        vid.setAttribute('height', 'auto');
    } else {
        vid.setAttribute('width', 'auto');
        vid.setAttribute('height', h);


video {

Git and nasty "error: cannot lock existing info/refs fatal"

What worked for me was:

  1. Remove .git/logs/refs/remotes/origin/branch
  2. Remove .git/refs/remotes/origin/branch
  3. Run git gc --prune=now

UNIX export command

export is used to set environment variables. For example:

export EDITOR=pico

Will set your default text editor to be the pico command.

How to recover a dropped stash in Git?

If you didn't close the terminal, just look at the output from git stash pop and you'll have the object ID of the dropped stash. It normally looks like this:

$ git stash pop
Dropped refs/stash@{0} (2ca03e22256be97f9e40f08e6d6773c7d41dbfd1)

(Note that git stash drop also produces the same line.)

To get that stash back, just run git branch tmp 2cae03e, and you'll get it as a branch. To convert this to a stash, run:

git stash apply tmp
git stash

Having it as a branch also allows you to manipulate it freely; for example, to cherry-pick it or merge it.

How to set a maximum execution time for a mysql query?

pt_kill has an option for such. But it is on-demand, not continually monitoring. It does what @Rafa suggested. However see --sentinel for a hint of how to come close with cron.

Access-control-allow-origin with multiple domains

There can only be one Access-Control-Allow-Origin response header, and that header can only have one origin value. Therefore, in order to get this to work, you need to have some code that:

  1. Grabs the Origin request header.
  2. Checks if the origin value is one of the whitelisted values.
  3. If it is valid, sets the Access-Control-Allow-Origin header with that value.

I don't think there's any way to do this solely through the web.config.

if (ValidateRequest()) {
    Response.AddHeader("Access-Control-Allow-Origin", Request.UrlReferrer.GetLeftPart(UriPartial.Authority));

    Response.AddHeader("Access-Control-Allow-Credentials", "true");

    Response.AddHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");

How to use null in switch

switch(i) will throw a NullPointerException if i is null, because it will try to unbox the Integer into an int. So case null, which happens to be illegal, would never have been reached anyway.

You need to check that i is not null before the switch statement.

ReadFile in Base64 Nodejs

Latest and greatest way to do this:

Node supports file and buffer operations with the base64 encoding:

const fs = require('fs');
const contents = fs.readFileSync('/path/to/file.jpg', {encoding: 'base64'});

Or using the new promises API:

const fs = require('fs').promises;
const contents = await fs.readFile('/path/to/file.jpg', {encoding: 'base64'});

Ignoring new fields on JSON objects using Jackson

Make sure that you place the @JsonIgnoreProperties(ignoreUnknown = true) annotation to the parent POJO class which you want to populate as a result of parsing the JSON response and not the class where the conversion from JSON to Java Object is taking place.

Convert seconds to HH-MM-SS with JavaScript?

var  timeInSec = "661"; //even it can be string

String.prototype.toHHMMSS = function () { 
   /* extend the String by using prototypical inheritance */
    var seconds = parseInt(this, 10); // don't forget the second param
    var hours   = Math.floor(seconds / 3600);
    var minutes = Math.floor((seconds - (hours * 3600)) / 60);
    seconds = seconds - (hours * 3600) - (minutes * 60);

    if (hours   < 10) {hours   = "0"+hours;}
    if (minutes < 10) {minutes = "0"+minutes;}
    if (seconds < 10) {seconds = "0"+seconds;}
    var time    = hours+':'+minutes+':'+seconds;
    return time;

alert("5678".toHHMMSS());   // "01:34:38"
console.log(timeInSec.toHHMMSS());   //"00:11:01"

we can make this function lot shorter and crisp but that decreases the readability, so we will write it as simple as possible and as stable as possible.

or you can check this working here:

Address already in use: JVM_Bind java

That error means that the you are trying to create a new ServerSocket on a port already in use by another ServerSocket. So try to make your application closing all sockets and connections you know about and be sure your application is completely terminated. Also check if there is another proces you launched by your program.

How does Git handle symbolic links?

"Editor's" note: This post may contain outdated information. Please see comments and this question regarding changes in Git since 1.6.1.

Symlinked directories:

It's important to note what happens when there is a directory which is a soft link. Any Git pull with an update removes the link and makes it a normal directory. This is what I learnt hard way. Some insights here and here.



 ls -l
 lrwxrwxrwx 1 admin adm   29 Sep 30 15:28 src/somedir -> /mnt/somedir

git add/commit/push

It remains the same

After git pull AND some updates found

 drwxrwsr-x 2 admin adm 4096 Oct  2 05:54 src/somedir

How to make a GridLayout fit screen size

For other peeps: If you have to use GridLayout due to project requirements then use it but I would suggest trying out TableLayout as it seems much easier to work with and achieves a similar result.





            android:text="Test 1"

            android:text="Test 2"

            android:text="Test 3"

            android:text="Test 4"



            android:text="Test 5"

            android:text="Test 6"



How can I plot separate Pandas DataFrames as subplots?

You may not need to use Pandas at all. Here's a matplotlib plot of cat frequencies:

enter image description here

x = np.linspace(0, 2*np.pi, 400)
y = np.sin(x**2)

f, axes = plt.subplots(2, 1)
for c, i in enumerate(axes):
  axes[c].plot(x, y)

How can I mock an ES6 module import using Jest?

To mock an ES6 dependency module default export using Jest:

import myModule from '../myModule';
import dependency from '../dependency';


// If necessary, you can place a mock implementation like this:
dependency.mockImplementation(() => 42);

describe('myModule', () => {
  it('calls the dependency once with double the input', () => {


The other options didn't work for my case.

What does "int 0x80" mean in assembly code?

Keep in mind that 0x80 = 80h = 128

You can see here that INT is just one of the many instructions (actually the Assembly Language representation (or should I say 'mnemonic') of it) that exists in the x86 instruction set. You can also find more information about this instruction in Intel's own manual found here.

To summarize from the PDF:

INT n/INTO/INT 3—Call to Interrupt Procedure

The INT n instruction generates a call to the interrupt or exception handler specified with the destination operand. The destination operand specifies a vector from 0 to 255, encoded as an 8-bit unsigned intermediate value. The INT n instruction is the general mnemonic for executing a software-generated call to an interrupt handler.

As you can see 0x80 is the destination operand in your question. At this point the CPU knows that it should execute some code that resides in the Kernel, but what code? That is determined by the Interrupt Vector in Linux.

One of the most useful DOS software interrupts was interrupt 0x21. By calling it with different parameters in the registers (mostly ah and al) you could access various IO operations, string output and more.

Most Unix systems and derivatives do not use software interrupts, with the exception of interrupt 0x80, used to make system calls. This is accomplished by entering a 32-bit value corresponding to a kernel function into the EAX register of the processor and then executing INT 0x80.

Take a look at this please where other available values in the interrupt handler tables are shown:

enter image description here

As you can see the table points the CPU to execute a system call. You can find the Linux System Call table here.

So by moving the value 0x1 to EAX register and calling the INT 0x80 in your program, you can make the process go execute the code in Kernel which will stop (exit) the current running process (on Linux, x86 Intel CPU).

A hardware interrupt must not be confused with a software interrupt. Here is a very good answer on this regard.

This also is good source.

Why should I use core.autocrlf=true in Git?

The only specific reasons to set autocrlf to true are:

  • avoid git status showing all your files as modified because of the automatic EOL conversion done when cloning a Unix-based EOL Git repo to a Windows one (see issue 83 for instance)
  • and your coding tools somehow depends on a native EOL style being present in your file:

Unless you can see specific treatment which must deal with native EOL, you are better off leaving autocrlf to false (git config --global core.autocrlf false).

Note that this config would be a local one (because config isn't pushed from repo to repo)

If you want the same config for all users cloning that repo, check out "What's the best CRLF handling strategy with git?", using the text attribute in the .gitattributes file.


*.vcproj    text eol=crlf
*.sh        text eol=lf

Note: starting git 2.8 (March 2016), merge markers will no longer introduce mixed line ending (LF) in a CRLF file.
See "Make Git use CRLF on its “<<<<<<< HEAD” merge lines"

M_PI works with math.h but not with cmath in Visual Studio

As suggested by user7860670, right-click on the project, select properties, navigate to C/C++ -> Preprocessor and add _USE_MATH_DEFINES to the Preprocessor Definitions.

That's what worked for me.

Difference between /res and /assets directories

Both are pretty similar. The real main difference between the two is that in the res directory each file is given a pre-compiled ID which can be accessed easily through[res id]. This is useful to quickly and easily access images, sounds, icons...

The assets directory is more like a filesystem and provides more freedom to put any file you would like in there. You then can access each of the files in that system as you would when accessing any file in any file system through Java. This directory is good for things such as game details, dictionaries,...etc. Hope that helps.

How can I find my php.ini on wordpress?

I see this question so much! everywhere I look lacks the real answer.

The php.ini should be in the wp-admin directory, if it isn't just create it and then define whats needed, by default it should contain.

upload_max_filesize = 64M
post_max_size = 64M
max_execution_time = 300

Jquery click event not working after append method

This problem could be solved as mentioned using the .on on jQuery 1.7+ versions.

Unfortunately, this didn't work within my code (and I have 1.11) so I used:

$('body').delegate('.logout-link','click',function() {

As of jQuery 3.0, .delegate() has been deprecated. It was superseded by the .on() method since jQuery 1.7, so its use was already discouraged. For earlier versions, however, it remains the most effective means to use event delegation. More information on event binding and delegation is in the .on() method. In general, these are the equivalent templates for the two methods:

// jQuery 1.4.3+
$( elements ).delegate( selector, events, data, handler );
// jQuery 1.7+
$( elements ).on( events, selector, data, handler );

This comment might help others :) !

while EOF in JAVA?

Each call to nextLine() moves onto the next line, so when you are actually at the last readable line and the while check passes inspection, the next call to nextLine() will return EOF.

Perhaps you could do one of the following instead:

If fileReader is of type Scanner:

while ((line = fileReader.hasNextLine()) != null) {
    String line = fileReader.nextLine(); 

If fileReader is of type BufferedReader:

String line;
while ((line = fileReader.readLine()) != null) {

So you're reading the current line in the while condition and saving the line in a string for later use.

Random word generator- Python

There are a number of dictionary files available online - if you're on linux, a lot of (all?) distros come with an /etc/dictionaries-common/words file, which you can easily parse (words = open('/etc/dictionaries-common/words').readlines(), eg) for use.

Hibernate Error: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session

I have the same error I was replacing my Set with a new one get from Jackson.

To solve this I keep the existing set, I remove from the old set the element unknown into the new list with retainAll. Then I add the new ones with addAll.


No need to have the Session and manipulate it.

Why can't I define a static method in a Java interface?

Java 8 permits static interface methods

With Java 8, interfaces can have static methods. They can also have concrete instance methods, but not instance fields.

There are really two questions here:

  1. Why, in the bad old days, couldn't interfaces contain static methods?
  2. Why can't static methods be overridden?

Static methods in interfaces

There was no strong technical reason why interfaces couldn't have had static methods in previous versions. This is summed up nicely by the poster of a duplicate question. Static interface methods were initially considered as a small language change, and then there was an official proposal to add them in Java 7, but it was later dropped due to unforeseen complications.

Finally, Java 8 introduced static interface methods, as well as override-able instance methods with a default implementation. They still can't have instance fields though. These features are part of the lambda expression support, and you can read more about them in Part H of JSR 335.

Overriding static methods

The answer to the second question is a little more complicated.

Static methods are resolvable at compile time. Dynamic dispatch makes sense for instance methods, where the compiler can't determine the concrete type of the object, and, thus, can't resolve the method to invoke. But invoking a static method requires a class, and since that class is known statically—at compile time—dynamic dispatch is unnecessary.

A little background on how instance methods work is necessary to understand what's going on here. I'm sure the actual implementation is quite different, but let me explain my notion of method dispatch, which models observed behavior accurately.

Pretend that each class has a hash table that maps method signatures (name and parameter types) to an actual chunk of code to implement the method. When the virtual machine attempts to invoke a method on an instance, it queries the object for its class and looks up the requested signature in the class's table. If a method body is found, it is invoked. Otherwise, the parent class of the class is obtained, and the lookup is repeated there. This proceeds until the method is found, or there are no more parent classes—which results in a NoSuchMethodError.

If a superclass and a subclass both have an entry in their tables for the same method signature, the sub class's version is encountered first, and the superclass's version is never used—this is an "override".

Now, suppose we skip the object instance and just start with a subclass. The resolution could proceed as above, giving you a sort of "overridable" static method. The resolution can all happen at compile-time, however, since the compiler is starting from a known class, rather than waiting until runtime to query an object of an unspecified type for its class. There is no point in "overriding" a static method since one can always specify the class that contains the desired version.

Constructor "interfaces"

Here's a little more material to address the recent edit to the question.

It sounds like you want to effectively mandate a constructor-like method for each implementation of IXMLizable. Forget about trying to enforce this with an interface for a minute, and pretend that you have some classes that meet this requirement. How would you use it?

class Foo implements IXMLizable<Foo> {
  public static Foo newInstanceFromXML(Element e) { ... }

Foo obj = Foo.newInstanceFromXML(e);

Since you have to explicitly name the concrete type Foo when "constructing" the new object, the compiler can verify that it does indeed have the necessary factory method. And if it doesn't, so what? If I can implement an IXMLizable that lacks the "constructor", and I create an instance and pass it to your code, it is an IXMLizable with all the necessary interface.

Construction is part of the implementation, not the interface. Any code that works successfully with the interface doesn't care about the constructor. Any code that cares about the constructor needs to know the concrete type anyway, and the interface can be ignored.

Renaming Columns in an SQL SELECT Statement

you have to rename each column

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

Get File Path (ends with folder)

Use Application.GetSaveAsFilename() in the same way that you used Application.GetOpenFilename()

Intent from Fragment to Activity

use getContext() instead of MainActivity.this

Intent intent = new Intent(getContext(), SecondActivity.class);

How to select clear table contents without destroying the table?

There is a condition that most of these solutions do not address. I revised Patrick Honorez's solution to handle it. I felt I had to share this because I was pulling my hair out when the original function was occasionally clearing more data that I expected.

The situation happens when the table only has one column and the .SpecialCells(xlCellTypeConstants).ClearContents attempts to clear the contents of the top row. In this situation, only one cell is selected (the top row of the table that only has one column) and the SpecialCells command applies to the entire sheet instead of the selected range. What was happening to me was other cells on the sheet that were outside of my table were also getting cleared.

I did some digging and found this advice from Mathieu Guindon: Range SpecialCells ClearContents clears whole sheet

Range({any single cell}).SpecialCells({whatever}) seems to work off the entire sheet.

Range({more than one cell}).SpecialCells({whatever}) seems to work off the specified cells.

If the list/table only has one column (in row 1), this revision will check to see if the cell has a formula and if not, it will only clear the contents of that one cell.

Public Sub ClearList(lst As ListObject)
'Clears a listObject while leaving 1 empty row + formula
'With special help from this post to handle a single column table.
'   Range({any single cell}).SpecialCells({whatever}) seems to work off the entire sheet.
'   Range({more than one cell}).SpecialCells({whatever}) seems to work off the specified cells.

    On Error Resume Next
    With lst
        '.Range.Worksheet.Activate ' Enable this if you are debugging 
        If .ShowAutoFilter Then .AutoFilter.ShowAllData
        If .DataBodyRange.Rows.Count = 1 Then Exit Sub ' Table is already clear
        If .DataBodyRange.Columns.Count > 1 Then ' Check to see if SpecialCells is going to evaluate just one cell.
        ElseIf Not .Range.HasFormula Then
            ' Only one cell in range and it does not contain a formula.
        End If

        .Resize .Range.Rows("1:2")

        ' Reset used range on the sheet
        Dim X
        X = .Range.Worksheet.UsedRange.Rows.Count 'see J-Walkenbach tip 73

    End With

End Sub

A final step I included is a tip that is attributed to John Walkenbach, sometimes noted as J-Walkenbach tip 73 Automatically Resetting The Last Cell

What "wmic bios get serialnumber" actually retrieves?

run cmd

Enter wmic baseboard get product,version,serialnumber

Press the enter key. The result you see under serial number column is your motherboard serial number

Splitting words into letters in Java

You can use

String [] strArr = Str.split("");

Where does pip install its packages?

pip when used with virtualenv will generally install packages in the path <virtualenv_name>/lib/<python_ver>/site-packages.

For example, I created a test virtualenv named venv_test with Python 2.7, and the django folder is in venv_test/lib/python2.7/site-packages/django.

How do I insert a drop-down menu for a simple Windows Forms app in Visual Studio 2008?

You can use a ComboBox with its ComboBoxStyle (appears as DropDownStyle in later versions) set to DropDownList. See:

Selenium Finding elements by class name in python

As per the HTML:

    <p class="content">Link1.</p>
    <p class="content">Link2.</p>

Two(2) <p> elements are having the same class content.

So to filter the elements having the same class i.e. content and create a list you can use either of the following Locator Strategies:

  • Using class_name:

    elements = driver.find_elements_by_class_name("content")
  • Using css_selector:

     elements = driver.find_elements_by_css_selector(".content")
  • Using xpath:

    elements = driver.find_elements_by_xpath("//*[@class='content']")

Ideally, to click on the element you need to induce WebDriverWait for the visibility_of_all_elements_located() and you can use either of the following Locator Strategies:

  • Using CLASS_NAME:

    elements = WebDriverWait(driver, 20).until(EC.visibility_of_all_elements_located((By.CLASS_NAME, "content")))

    elements = WebDriverWait(driver, 20).until(EC.visibility_of_all_elements_located((By.CSS_SELECTOR, ".content")))
  • Using XPATH:

    elements = WebDriverWait(driver, 20).until(EC.visibility_of_all_elements_located((By.XPATH, "//*[@class='content']")))
  • Note : You have to add the following imports :

    from import WebDriverWait
    from import By
    from import expected_conditions as EC


You can find a couple of relevant discussions in:

Single controller with multiple GET methods in ASP.NET Web API

Couldn't make any of the above routing solutions work -- some of the syntax seems to have changed and I'm still new to MVC -- in a pinch though I put together this really awful (and simple) hack which will get me by for now -- note, this replaces the "public MyObject GetMyObjects(long id)" method -- we change "id"'s type to a string, and change the return type to object.

// GET api/MyObjects/5
// GET api/MyObjects/function
public object GetMyObjects(string id)
    id = (id ?? "").Trim();

    // Check to see if "id" is equal to a "command" we support
    // and return alternate data.

    if (string.Equals(id, "count", StringComparison.OrdinalIgnoreCase))
        return db.MyObjects.LongCount();

    // We now return you back to your regularly scheduled
    // web service handler (more or less)

    var myObject = db.MyObjects.Find(long.Parse(id));
    if (myObject == null)
        throw new HttpResponseException

    return myObject;

Vlookup referring to table data in a different sheet

There might be something wrong with your formula if you are looking from another sheet maybe you have to change Sheet1 to Sheet2 ---> =VLOOKUP(M3,Sheet2!$A$2:$Q$47,13,FALSE) --- Where Sheet2 is your table array

Android: ListView elements with multiple clickable buttons

I Know it's late but this may help, this is an example how I write custom adapter class for different click actions

 public class CustomAdapter extends BaseAdapter {

    TextView title;
  Button button1,button2;

    public long getItemId(int position) {
        return position;

    public int getCount() {
        return mAlBasicItemsnav.size();  // size of your list array

    public Object getItem(int position) {
        return position;

    public View getView(int position, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = getLayoutInflater().inflate(R.layout.listnavsub_layout, null, false); // use sublayout which you want to inflate in your each list item

        title = (TextView) convertView.findViewById(; // see you have to find id by using convertView.findViewById 
      button1=(Button) convertView.findViewById(;
      button1.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            //your click action 

           // if you have different click action at different positions then
                       //click action of 1st list item on button click
                       //click action of 2st list item on button click

 // similarly for button 2

   button2=(Button) convertView.findViewById(;
      button2.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            //your click action 


        return convertView;

C# Error "The type initializer for ... threw an exception

This problem can occur if a class tries to get value of a non-existent key in web.config.

For example, the class has a static variable ClientID

private static string ClientID = System.Configuration.ConfigurationSettings.AppSettings["GoogleCalendarApplicationClientID"].ToString();

but the web.config doesn't contain the 'GoogleCalendarApplicationClientID' key, then the error will be thrown on any static function call or any class instance creation

Javascript pass values using POST

The code helped me to fulfill my requirement.

I have made some modifications and using a form I completed this. Here is my code-

Need a 'target' attribute for 'form' -- that's it!


<form id="view_form" name="view_form" method="post" action="view_report.php"  target="Map" >
  <input type="text" value="<?php echo $sale->myvalue1; ?>" name="my_value1"/>
  <input type="text" value="<?php echo $sale->myvalue2; ?>" name="my_value2"/>
  <input type="button" id="download" name="download" value="View report" onclick="view_my_report();"   /> 


function view_my_report() {     
   var mapForm = document.getElementById("view_form");"","Map","status=0,title=0,height=600,width=800,scrollbars=1");

   if (map) {
   } else {
      alert('You must allow popups for this map to work.');

Full code is explained showing normal form and form elements.

Jest spyOn function called

In your test code your are trying to pass App to the spyOn function, but spyOn will only work with objects, not classes. Generally you need to use one of two approaches here:

1) Where the click handler calls a function passed as a prop, e.g.

class App extends Component {

  myClickFunc = () => {
      console.log('clickity clickcty');
  render() {
    return (
      <div className="App">
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        <p className="App-intro" onClick={this.myClickFunc}>
          To get started, edit <code>src/App.js</code> and save to reload.

You can now pass in a spy function as a prop to the component, and assert that it is called:

describe('my sweet test', () => {
 it('clicks it', () => {
    const spy = jest.fn();
    const app = shallow(<App someCallback={spy} />)
    const p = app.find('.App-intro')

2) Where the click handler sets some state on the component, e.g.

class App extends Component {
  state = {
      aProperty: 'first'

  myClickFunc = () => {
      console.log('clickity clickcty');
          aProperty: 'second'
  render() {
    return (
      <div className="App">
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        <p className="App-intro" onClick={this.myClickFunc}>
          To get started, edit <code>src/App.js</code> and save to reload.

You can now make assertions about the state of the component, i.e.

describe('my sweet test', () => {
 it('clicks it', () => {
    const app = shallow(<App />)
    const p = app.find('.App-intro')

C# elegant way to check if a property's property is null

When I need to chain calls like that, I rely on a helper method I created, TryGet():

    public static U TryGet<T, U>(this T obj, Func<T, U> func)
        return obj.TryGet(func, default(U));

    public static U TryGet<T, U>(this T obj, Func<T, U> func, U whenNull)
        return obj == null ? whenNull : func(obj);

In your case, you would use it like so:

    int value = ObjectA
        .TryGet(p => p.PropertyA)
        .TryGet(p => p.PropertyB)
        .TryGet(p => p.PropertyC, defaultVal);

Convert XML to JSON (and back) using Javascript - my own library (updated URL from

This library provides XML to JSON (JavaScript Objects) and vice versa javascript conversion functions. The library is very small and doesn't require any other additional libraries.

API functions

  • new X2JS() - to create your instance to access all library functionality. Also you could specify optional configuration options here
  • X2JS.xml2json - Convert XML specified as DOM Object to JSON
  • X2JS.json2xml - Convert JSON to XML DOM Object
  • X2JS.xml_str2json - Convert XML specified as string to JSON
  • X2JS.json2xml_str - Convert JSON to XML string

Online Demo on

var x2js = new X2JS();
function convertXml2JSon() {

function convertJSon2XML() {


android button selector

Create custom_selector.xml in drawable folder

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="">
   <item android:drawable="@drawable/unselected" android:state_pressed="true" />
   <item android:drawable="@drawable/selected" />

Create selected.xml shape in drawable folder

<shape xmlns:android="" android:shape="rectangle" android:padding="90dp">
   <solid android:color="@color/selected"/>
   <padding />
   <stroke android:color="#000" android:width="1dp"/>
   <corners android:bottomRightRadius="15dp" android:bottomLeftRadius="15dp" android:topLeftRadius="15dp" android:topRightRadius="15dp"/>

Create unselected.xml shape in drawable folder

<shape xmlns:android="" android:shape="rectangle" android:padding="90dp">
   <solid android:color="@color/unselected"/>
   <padding />
   <stroke android:color="#000" android:width="1dp"/>
   <corners android:bottomRightRadius="15dp" android:bottomLeftRadius="15dp" android:topLeftRadius="15dp" android:topRightRadius="15dp"/>

Add following colors for selected/unselected state in color.xml of values folder

<color name="selected">#a8cf45</color>
<color name="unselected">#ff8cae3b</color>

you can check complete solution from here

Why isn't textarea an input[type="textarea"]?

A textarea can contain multiple lines of text, so one wouldn't be able to pre-populate it using a value attribute.

Similarly, the select element needs to be its own element to accommodate option sub-elements.

How to disable submit button once it has been clicked?

tested on IE11, FF53, GC58 :

onclick="var e=this;setTimeout(function(){e.disabled=true;},0);return true;"

How to subtract/add days from/to a date?

There is of course a lubridate solution for this:

date <- "2009-10-01"

ymd(date) - 5
# [1] "2009-09-26"

is the same as

ymd(date) - days(5)
# [1] "2009-09-26"

Other time formats could be:

ymd(date) - months(5)
# [1] "2009-05-01"

ymd(date) - years(5)
# [1] "2004-10-01"

ymd(date) - years(1) - months(2) - days(3)
# [1] "2008-07-29"

Run an OLS regression with Pandas Data Frame

Statsmodels kan build an OLS model with column references directly to a pandas dataframe.

Short and sweet:

model = sm.OLS(df[y], df[x]).fit()

Code details and regression summary:

# imports
import pandas as pd
import statsmodels.api as sm
import numpy as np

# data
df = pd.DataFrame(np.random.randint(0,100,size=(100, 3)), columns=list('ABC'))

# assign dependent and independent / explanatory variables
variables = list(df.columns)
y = 'A'
x = [var for var in variables if var not in y ]

# Ordinary least squares regression
model_Simple = sm.OLS(df[y], df[x]).fit()

# Add a constant term like so:
model = sm.OLS(df[y], sm.add_constant(df[x])).fit()



                            OLS Regression Results                            
Dep. Variable:                      A   R-squared:                       0.019
Model:                            OLS   Adj. R-squared:                 -0.001
Method:                 Least Squares   F-statistic:                    0.9409
Date:                Thu, 14 Feb 2019   Prob (F-statistic):              0.394
Time:                        08:35:04   Log-Likelihood:                -484.49
No. Observations:                 100   AIC:                             975.0
Df Residuals:                      97   BIC:                             982.8
Df Model:                           2                                         
Covariance Type:            nonrobust                                         
                 coef    std err          t      P>|t|      [0.025      0.975]
const         43.4801      8.809      4.936      0.000      25.996      60.964
B              0.1241      0.105      1.188      0.238      -0.083       0.332
C             -0.0752      0.110     -0.681      0.497      -0.294       0.144
Omnibus:                       50.990   Durbin-Watson:                   2.013
Prob(Omnibus):                  0.000   Jarque-Bera (JB):                6.905
Skew:                           0.032   Prob(JB):                       0.0317
Kurtosis:                       1.714   Cond. No.                         231.

How to directly get R-squared, Coefficients and p-value:

# commands:

# demo:
const    43.480106
B         0.124130
C        -0.075156
dtype: float64

const    0.000003
B        0.237924
C        0.497400
dtype: float64


How to uninstall Jenkins?

There is no uninstaller. Therefore, you need to:

  • Delete the directory containing Jenkins (or, if you're deploying the war -- remove the war from your container).

  • Remove ~/.jenkins.

  • Remove you startup scripts.

Rails Model find where not equal

You should always include the table name in the SQL query when dealing with associations.

Indeed if another table has the user_id column and you join both tables, you will have an ambiguous column name in the SQL query (i.e. troubles).

So, in your example:

GroupUser.where("groups_users.user_id != ?", me)

Or a bit more verbose:

GroupUser.where("#{table_name}.user_id IS NOT ?", me)

Note that if you are using a hash, you don't need to worry about that because Rails takes care of it for you:

GroupUser.where(user: me)

In Rails 4, as said by @dr4k3, the query method not has been added:

GroupUser.where.not(user: me)

Vuejs: v-model array in multiple input

If you were asking how to do it in vue2 and make options to insert and delete it, please, have a look an js fiddle

new Vue({_x000D_
  el: '#app',_x000D_
  data: {_x000D_
    finds: [] _x000D_
  methods: {_x000D_
    addFind: function () {_x000D_
      this.finds.push({ value: 'def' });_x000D_
    deleteFind: function (index) {_x000D_
      this.finds.splice(index, 1);_x000D_
<script src="[email protected]/dist/vue.js"></script>_x000D_
<div id="app">_x000D_
  <div v-for="(find, index) in finds">_x000D_
    <input v-model="find.value">_x000D_
    <button @click="deleteFind(index)">_x000D_
  <button @click="addFind">_x000D_
    New Find_x000D_
  <pre>{{ $data }}</pre>_x000D_

What regular expression will match valid international phone numbers?

Try the following API for phone number validation. Also this will return the Country, Area and Provider



How to install maven on redhat linux

I made the following script:


# Target installation location

# Link to binary tar.gz archive
# See

# Configuration parameters used to start up the JVM running Maven, i.e. "-Xms256m -Xmx512m"
# See
MAVEN_OPTS="" # Optional (not needed)

if [[ ! -d $MAVEN_HOME ]]; then
  # Create nonexistent subdirectories recursively
  mkdir -p $MAVEN_HOME

  # Curl location of tar.gz archive & extract without first directory
  curl -L $MAVEN_BINARY_TAR_GZ_ARCHIVE | tar -xzf - -C $MAVEN_HOME --strip 1

  # Creating a symbolic/soft link to Maven in the primary directory of executable commands on the system
  ln -s $MAVEN_HOME/bin/mvn /usr/bin/mvn

  # Permanently set environmental variable (if not null)
  if [[ -n $MAVEN_OPTS ]]; then
    echo "export MAVEN_OPTS=$MAVEN_OPTS" >> ~/.bashrc

  # Using MAVEN_HOME, MVN_HOME, or M2 as your env var is irrelevant, what counts
  # is your $PATH environment.
  # See
  echo "export PATH=$MAVEN_HOME/bin:$PATH" >> ~/.bashrc
  # Do nothing if target installation directory already exists
  echo "'$MAVEN_HOME' already exists, please uninstall existing maven first."

How to get a complete list of object's methods and attributes?

This is how I do it, useful for simple custom objects to which you keep adding attributes:

Given an object created with obj = type("Obj",(object,),{}), or by simply:

class Obj: pass
obj = Obj()

Add some attributes: = 'gary'
obj.age = 32

then, to obtain a dictionary with only the custom attributes:

{key: value for key, value in obj.__dict__.items() if not key.startswith("__")}

# {'name': 'gary', 'age': 32}

What is the difference between user and kernel modes in operating systems?

I'm going to take a stab in the dark and guess you're talking about Windows. In a nutshell, kernel mode has full access to hardware, but user mode doesn't. For instance, many if not most device drivers are written in kernel mode because they need to control finer details of their hardware.

See also this wikibook.

jQuery selector regular expressions

$("input[name='option[colour]'] :checked ")

C++ static virtual members?

No, Static member function can't be virtual .since virtual concept is resolved at run time with the help of vptr, and vptr is non static member of a class.due to that static member function can't acess vptr so static member can't be virtual.

Count words in a string method?

lambda, in which splitting and storing of the counted words is dispensed with
and only counting is done

String text = "counting w/o apostrophe's problems or consecutive   spaces";

int count = text.codePoints().boxed().collect(
        () -> new int[] {0, 0},
        (a, c) -> {
          if( ".,; \t".indexOf( c ) >= 0 )
            a[1] = 0;
          else if( a[1]++ == 0 ) a[0]++;
        }, (a, b) -> {a[0] += b[0]; return( a );},
        a -> a[0] ) );

gets: 7
works as a status machine that counts the transitions from spacing characters .,; \t to words

How to alter a column and change the default value?

In case the above does not work for you (i.e.: you are working with new SQL or Azure) try the following:

1) drop existing column constraint (if any):

ALTER TABLE [table_name] DROP CONSTRAINT DF_my_constraint

2) create a new one:

ALTER TABLE [table_name] ADD CONSTRAINT DF_my_constraint  DEFAULT getdate() FOR column_name;

How to pass multiple parameter to @Directives (@Components) in Angular with TypeScript?

Similar to the above solutions I used @Input() in a directive and able to pass multiple arrays of values in the directive.

selector: '[selectorHere]',

@Input() options: any = {};


<input selectorHere [options]="selectorArray" />

Array from TS file

selectorArray= {
  align: 'left',
  prefix: '$',
  thousands: ',',
  decimal: '.',
  precision: 2

Vertical and horizontal align (middle and center) with CSS

This blog post describes two methods of centering a div both horizontally and vertically. One uses only CSS and will work with divs that have a fixed size; the other uses jQuery and will work divs for which you do not know the size in advance.

I've duplicated the CSS and jQuery examples from the blog post's demo here:


Assuming you have a div with a class of .classname, the css below should work.

The left:50%; top:50%; sets the top left corner of the div to the center of the screen; the margin:-75px 0 0 -135px; moves it to the left and up by half of the width and height of the fixed-size div respectively.

    margin:-75px 0 0 -135px;


            left: ($(window).width() - $('.className').outerWidth())/2,
            top: ($(window).height() - $('.className').outerHeight())/2
    // To initially run the function:

Here's a demo of the techniques in practice.

How to order results with findBy() in Doctrine

$ens = $em->getRepository('AcmeBinBundle:Marks')
                 array('id' => 'ASC')

Android: How can I pass parameters to AsyncTask's onPreExecute()?

why, how and which parameters are passed to Asynctask<>, see detail here. I think it is the best explanation.

Google's Android Documentation Says that :

An asynchronous task is defined by 3 generic types, called Params, Progress and Result, and 4 steps, called onPreExecute, doInBackground, onProgressUpdate and onPostExecute.

AsyncTask's generic types :

The three types used by an asynchronous task are the following:

Params, the type of the parameters sent to the task upon execution. Progress, the type of the progress units published during the background computation. Result, the type of the result of the background computation. Not all types are always used by an asynchronous task. To mark a type as unused, simply use the type Void:

 private class MyTask extends AsyncTask<Void, Void, Void> { ... }

You Can further refer :

Or You Can clear whats the role of AsyncTask by refering Sankar-Ganesh's Blog

Well The structure of a typical AsyncTask class goes like :

private class MyTask extends AsyncTask<X, Y, Z>

    protected void onPreExecute(){ 


This method is executed before starting the new Thread. There is no input/output values, so just initialize variables or whatever you think you need to do.

protected Z doInBackground(X...x){


The most important method in the AsyncTask class. You have to place here all the stuff you want to do in the background, in a different thread from the main one. Here we have as an input value an array of objects from the type “X” (Do you see in the header? We have “...extends AsyncTask” These are the TYPES of the input parameters) and returns an object from the type “Z”.

protected void onProgressUpdate(Y y){

} This method is called using the method publishProgress(y) and it is usually used when you want to show any progress or information in the main screen, like a progress bar showing the progress of the operation you are doing in the background.

protected void onPostExecute(Z z){

} This method is called after the operation in the background is done. As an input parameter you will receive the output parameter of the doInBackground method.

What about the X, Y and Z types?

As you can deduce from the above structure:

X – The type of the input variables value you want to set to the background process. This can be an array of objects.

 Y – The type of the objects you are going to enter in the onProgressUpdate method.

 Z – The type of the result from the operations you have done in the background process.

How do we call this task from an outside class? Just with the following two lines:

MyTask myTask = new MyTask();


Where x is the input parameter of the type X.

Once we have our task running, we can find out its status from “outside”. Using the “getStatus()” method.

myTask.getStatus(); and we can receive the following status:

RUNNING - Indicates that the task is running.

PENDING - Indicates that the task has not been executed yet.

FINISHED - Indicates that onPostExecute(Z) has finished.

Hints about using AsyncTask

Do not call the methods onPreExecute, doInBackground and onPostExecute manually. This is automatically done by the system.

You cannot call an AsyncTask inside another AsyncTask or Thread. The call of the method execute must be done in the UI Thread.

The method onPostExecute is executed in the UI Thread (here you can call another AsyncTask!).

The input parameters of the task can be an Object array, this way you can put whatever objects and types you want.

What is the difference between 'classic' and 'integrated' pipeline mode in IIS7?

In classic mode IIS works h ISAPI extensions and ISAPI filters directly. And uses two pipe lines , one for native code and other for managed code. You can simply say that in Classic mode IIS 7.x works just as IIS 6 and you dont get extra benefits out of IIS 7.x features.

In integrated mode IIS and ASP.Net are tightly coupled rather then depending on just two DLLs on as in case of classic mode.

Subquery returned more than 1 value.This is not permitted when the subquery follows =,!=,<,<=,>,>= or when the subquery is used as an expression

Use In instead of =

 select * from dbo.books
 where isbn in (select isbn from dbo.lending 
                where act between @fdate and @tdate
                and stat ='close'

or you can use Exists

SELECT t1.*,t2.*
FROM  books   t1 
WHERE  EXISTS ( SELECT * FROM dbo.lending t2 WHERE t1.isbn = t2.isbn and
                t2.act between @fdate and @tdate and t2.stat ='close' ) has key method?

JObject.ContainsKey(string propertyName) has been made as public method in 11.0.1 release

Documentation -

ASP.NET Web Api: The requested resource does not support http method 'GET'

Replace the following code in this path

Path :

App_Start => WebApiConfig.cs


            name: "DefaultApi",
            routeTemplate: "api/{controller}/{action}/{id}/{Param}",
            defaults: new { id = RouteParameter.Optional,
                            Param = RouteParameter.Optional }

PLS-00428: an INTO clause is expected in this SELECT statement

In PLSQL block, columns of select statements must be assigned to variables, which is not the case in SQL statements.

The second BEGIN's SQL statement doesn't have INTO clause and that caused the error.

   DSC           VARCHAR (512);
    WHERE PART_NUM = 'S0146404';

             || ','
             || RTRIM (PLANID.DESC_TEXT)
             || ','
             || CASE
                   WHEN PLANID.HIGH = 'TEST123'
                         WHEN TO_DATE (PROD.START_DATE) + 30 > SYSDATE
             || ','
             || 'GB'
             || ','
        INTO DSC
                ON PROD.PART_NUM = PLANID.VAL
                ON PROD.PROD_ID = PROD.ROW_ID
                ON VIS.PROD_ID = VISPROD.ROW_ID
       WHERE     PLANID.TYPE = 'Test Plan'
             AND PLANID.ACTIVE_FLG = 'Y'
             AND PROD.STATUS_CD = 'Active'


Outline effect to text

Multiple text-shadows..
Something like this:

var steps = 10,
    R = 0.6,
    theStyle = '1vw 1vw 3vw #005dab';
for (i = -steps; i <= steps; i += 1) {
    x = (i / steps) / 2;
    y = Math.sqrt(Math.pow(R, 2) - Math.pow(x, 2));
    theStyle = theStyle + ',' + x.toString() + 'vw ' + y.toString() + 'vw 0 #005dab';
    theStyle = theStyle + ',' + x.toString() + 'vw -' + y.toString() + 'vw 0 #005dab';
    theStyle = theStyle + ',' + y.toString() + 'vw ' + x.toString() + 'vw 0 #005dab';
    theStyle = theStyle + ',-' + y.toString() + 'vw ' + x.toString() + 'vw 0 #005dab';
document.getElementsByTagName("H1")[0].setAttribute("style", "text-shadow:" + theStyle);


Extract values in Pandas value_counts()

#!/usr/bin/env python

import pandas as pd

# Make example dataframe
df = pd.DataFrame([(1, 'Germany'),
                   (2, 'France'),
                   (3, 'Indonesia'),
                   (4, 'France'),
                   (5, 'France'),
                   (6, 'Germany'),
                   (7, 'UK'),
                  columns=['groupid', 'country'],
                  index=['a', 'b', 'c', 'd', 'e', 'f', 'g'])

# What you're looking for
values = df['country'].value_counts().keys().tolist()
counts = df['country'].value_counts().tolist()

Now, print(df['country'].value_counts()) gives:

France       3
Germany      2
UK           1
Indonesia    1

and print(values) gives:

['France', 'Germany', 'UK', 'Indonesia']

and print(counts) gives:

[3, 2, 1, 1]

How to split a comma separated string and process in a loop using JavaScript

you can Try the following snippet:

var str = "How are you doing today?";
var res = str.split("o");
console.log("My Result:",res)

and your output like that

My Result: H,w are y,u d,ing t,day?

Android Studio Could not initialize class org.codehaus.groovy.runtime.InvokerHelper

The problem in my case was in the discrepancy between the Gradle version installed globally and the one required by React Native. To fix it, I had to update the folder android/gradle/wrapper from the current 6.5 RN version from GH.

What is the incentive for curl to release the library for free?

I'm Daniel Stenberg.

I made curl

I founded the curl project back in 1998, I wrote the initial curl version and I created libcurl. I've written more than half of all the 24,000 commits done in the source code repository up to this point in time. I'm still the lead developer of the project. To a large extent, curl is my baby.

I shipped the first version of curl as open source since I wanted to "give back" to the open source world that had given me so much code already. I had used so much open source and I wanted to be as cool as the other open source authors.

Thanks to it being open source, literally thousands of people have been able to help us out over the years and have improved the products, the documentation. the web site and just about every other detail around the project. curl and libcurl would never have become the products that they are today were they not open source. The list of contributors now surpass 1900 names and currently the list grows with a few hundred names per year.

Thanks to curl and libcurl being open source and liberally licensed, they were immediately adopted in numerous products and soon shipped by operating systems and Linux distributions everywhere thus getting a reach beyond imagination.

Thanks to them being "everywhere", available and liberally licensed they got adopted and used everywhere and by everyone. It created a defacto transfer library standard.

At an estimated six billion installations world wide, we can safely say that curl is the most widely used internet transfer library in the world. It simply would not have gone there had it not been open source. curl runs in billions of mobile phones, a billion Windows 10 installations, in a half a billion games and several hundred million TVs - and more.

Should I have released it with proprietary license instead and charged users for it? It never occured to me, and it wouldn't have worked because I would never had managed to create this kind of stellar project on my own. And projects and companies wouldn't have used it.

Why do I still work on curl?

Now, why do I and my fellow curl developers still continue to develop curl and give it away for free to the world?

  1. I can't speak for my fellow project team members. We all participate in this for our own reasons.
  2. I think it's still the right thing to do. I'm proud of what we've accomplished and I truly want to make the world a better place and I think curl does its little part in this.
  3. There are still bugs to fix and features to add!
  4. curl is free but my time is not. I still have a job and someone still has to pay someone for me to get paid every month so that I can put food on the table for my family. I charge customers and companies to help them with curl. You too can get my help for a fee, which then indirectly helps making sure that curl continues to evolve, remain free and the kick-ass product it is.
  5. curl was my spare time project for twenty years before I started working with it full time. I've had great jobs and worked on awesome projects. I've been in a position of luxury where I could continue to work on curl on my spare time and keep shipping a quality product for free. My work on curl has given me friends, boosted my career and taken me to places I would not have been at otherwise.
  6. I would not do it differently if I could back and do it again.

Am I proud of what we've done?

Yes. So insanely much.

But I'm not satisfied with this and I'm not just leaning back, happy with what we've done. I keep working on curl every single day, to improve, to fix bugs, to add features and to make sure curl keeps being the number one file transfer solution for the world even going forward.

We do mistakes along the way. We make the wrong decisions and sometimes we implement things in crazy ways. But to win in the end and to conquer the world is about patience and endurance and constantly going back and reconsidering previous decisions and correcting previous mistakes. To continuously iterate, polish off rough edges and gradually improve over time.

Never give in. Never stop. Fix bugs. Add features. Iterate. To the end of time.

For real?

Yeah. For real.

Do I ever get tired? Is it ever done?

Sure I get tired at times. Working on something every day for over twenty years isn't a paved downhill road. Sometimes there are obstacles. During times things are rough. Occasionally people are just as ugly and annoying as people can be.

But curl is my life's project and I have patience. I have thick skin and I don't give up easily. The tough times pass and most days are awesome. I get to hang out with awesome people and the reward is knowing that my code helps driving the Internet revolution everywhere is an ego boost above normal.

curl will never be "done" and so far I think work on curl is pretty much the most fun I can imagine. Yes, I still think so even after twenty years in the driver's seat. And as long as I think it's fun I intend to keep at it.

pip install mysql-python fails with EnvironmentError: mysql_config not found

For centos users:

yum install -y mysql-devel python-devel python-setuptools


pip install MySQL-python

If this solution doesn't work, and print gcc compile error like:
_mysql.c:29:20: error: Python.h: No such file or directory

You need to specify the path of Python.h, like this:
pip install --global-option=build_ext --global-option="-I/usr/include/python2.6" MySQL-python

How to change the name of a Django app?

Follow these steps to change an app's name in Django:

  1. Rename the folder which is in your project root
  2. Change any references to your app in their dependencies, i.e. the app's, , '' , and files.
  3. Edit the database table django_content_type with the following command: UPDATE django_content_type SET app_label='<NewAppName>' WHERE app_label='<OldAppName>'
  4. Also if you have models, you will have to rename the model tables. For postgres use ALTER TABLE <oldAppName>_modelName RENAME TO <newAppName>_modelName. For mysql too I think it is the same (as mentioned by @null_radix)
  5. (For Django >= 1.7) Update the django_migrations table to avoid having your previous migrations re-run: UPDATE django_migrations SET app='<NewAppName>' WHERE app='<OldAppName>'. Note: there is some debate (in comments) if this step is required for Django 1.8+; If someone knows for sure please update here.
  6. If your 's Meta Class has app_name listed, make sure to rename that too (mentioned by @will).
  7. If you've namespaced your static or templates folders inside your app, you'll also need to rename those. For example, rename old_app/static/old_app to new_app/static/new_app.
  8. For renaming django models, you'll need to change entry in DB. For postgreSQL use UPDATE django_content_type SET name='<newModelName>' where name='<oldModelName>' AND app_label='<OldAppName>'

Meta point (If using virtualenv): Worth noting, if you are renaming the directory that contains your virtualenv, there will likely be several files in your env that contain an absolute path and will also need to be updated. If you are getting errors such as ImportError: No module named ... this might be the culprit. (thanks to @danyamachine for providing this).

Other references: you might also want to refer the below links for a more complete picture

  1. Renaming an app with Django and South
  2. How do I migrate a model out of one django app and into a new one?
  3. How to change the name of a Django app?
  4. Backwards migration with Django South
  5. Easiest way to rename a model using Django/South?
  6. Python code (thanks to A.Raouf) to automate the above steps (Untested code. You have been warned!)
  7. Python code (thanks to rafaponieman) to automate the above steps (Untested code. You have been warned!)

Get elements by attribute when querySelectorAll is not available without using libraries?

You could write a function that runs getElementsByTagName('*'), and returns only those elements with a "data-foo" attribute:

function getAllElementsWithAttribute(attribute)
  var matchingElements = [];
  var allElements = document.getElementsByTagName('*');
  for (var i = 0, n = allElements.length; i < n; i++)
    if (allElements[i].getAttribute(attribute) !== null)
      // Element exists with attribute. Add to array.
  return matchingElements;



How to input a path with a white space?

SOME_PATH=/mnt/someProject/some\ path

should work

how to read all files inside particular folder

If you are looking to copy all the text files in one folder to merge and copy to another folder, you can do this to achieve that:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace HowToCopyTextFiles
  class Program
    static void Main(string[] args)
      string mydocpath=Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);     
      StringBuilder sb = new StringBuilder();
      foreach (string txtName in Directory.GetFiles(@"D:\Links","*.txt"))
        using (StreamReader sr = new StreamReader(txtName))
          sb.AppendLine("= = = = = =");
      using (StreamWriter outfile=new StreamWriter(mydocpath + @"\AllTxtFiles.txt"))

Adding up BigDecimals using Streams

Original answer

Yes, this is possible:

List<BigDecimal> bdList = new ArrayList<>();
//populate list
BigDecimal result =
        .reduce(BigDecimal.ZERO, BigDecimal::add);

What it does is:

  1. Obtain a List<BigDecimal>.
  2. Turn it into a Stream<BigDecimal>
  3. Call the reduce method.

    3.1. We supply an identity value for addition, namely BigDecimal.ZERO.

    3.2. We specify the BinaryOperator<BigDecimal>, which adds two BigDecimal's, via a method reference BigDecimal::add.

Updated answer, after edit

I see that you have added new data, therefore the new answer will become:

List<Invoice> invoiceList = new ArrayList<>();
Function<Invoice, BigDecimal> totalMapper = invoice -> invoice.getUnit_price().multiply(invoice.getQuantity());
BigDecimal result =
        .reduce(BigDecimal.ZERO, BigDecimal::add);

It is mostly the same, except that I have added a totalMapper variable, that has a function from Invoice to BigDecimal and returns the total price of that invoice.

Then I obtain a Stream<Invoice>, map it to a Stream<BigDecimal> and then reduce it to a BigDecimal.

Now, from an OOP design point I would advice you to also actually use the total() method, which you have already defined, then it even becomes easier:

List<Invoice> invoiceList = new ArrayList<>();
BigDecimal result =
        .reduce(BigDecimal.ZERO, BigDecimal::add);

Here we directly use the method reference in the map method.

How to convert a hex string to hex number

Try this:

hex_str = "0xAD4"
hex_int = int(hex_str, 16)
new_int = hex_int + 0x200
print hex(new_int)

If you don't like the 0x in the beginning, replace the last line with

print hex(new_int)[2:]

Javascript: The prettiest way to compare one value against multiple values

What i use to do, is put those multiple values in an array like

var options = [foo, bar];

and then, use indexOf()

if(options.indexOf(foobar) > -1){
   //do something

for prettiness:

if([foo, bar].indexOf(foobar) +1){
   //you can't get any more pretty than this :)

and for the older browsers:
( )

if (!Array.prototype.indexOf) {
    Array.prototype.indexOf = function (searchElement /*, fromIndex */ ) {
        "use strict";
        if (this == null) {
            throw new TypeError();
        var t = Object(this);
        var len = t.length >>> 0;
        if (len === 0) {
            return -1;
        var n = 0;
        if (arguments.length > 0) {
            n = Number(arguments[1]);
            if (n != n) { // shortcut for verifying if it's NaN
                n = 0;
            } else if (n != 0 && n != Infinity && n != -Infinity) {
                n = (n > 0 || -1) * Math.floor(Math.abs(n));
        if (n >= len) {
            return -1;
        var k = n >= 0 ? n : Math.max(len - Math.abs(n), 0);
        for (; k < len; k++) {
            if (k in t && t[k] === searchElement) {
                return k;
        return -1;

Unable to convert MySQL date/time value to System.DateTime

if "allow zero datetime=true" is not working then use the following sollutions:-

Add this to your connection string: "allow zero datetime=no" - that made the type cast work perfectly.

warning: implicit declaration of function

Don't forget, if any functions that are called in your function and their prototypes must be situated above your function in the code otherwise the compiler might not find them before it attempts to compile your function. This will generate the error in question.

How to set a default entity property value with Hibernate

If you want a real database default value, use columnDefinition:

@Column(name = "myColumn", nullable = false, columnDefinition = "int default 100") 

Notice that the string in columnDefinition is database dependent. Also if you choose this option, you have to use dynamic-insert, so Hibernate doesn't include columns with null values on insert. Otherwise talking about default is irrelevant.

But if you don't want database default value, but simply a default value in your Java code, just initialize your variable like that - private Integer myColumn = 100;

Angular.js: How does $eval work and why is it different from vanilla eval?

From the test,

it('should allow passing locals to the expression', inject(function($rootScope) {
  expect($rootScope.$eval('a+1', {a: 2})).toBe(3);

  $rootScope.$eval(function(scope, locals) {
    scope.c = locals.b + 4;
  }, {b: 3});

We also can pass locals for evaluation expression.

How do I read a response from Python Requests?

Requests doesn't have an equivalent to Urlib2's read().

>>> import requests
>>> response = requests.get("")
>>> print response.content
'<!doctype html><html itemscope="" itemtype=""><head>....'
>>> print response.content == response.text

It looks like the POST request you are making is returning no content. Which is often the case with a POST request. Perhaps it set a cookie? The status code is telling you that the POST succeeded after all.

Edit for Python 3:

Python now handles data types differently. response.content returns a sequence of bytes (integers that represent ASCII) while response.text is a string (sequence of chars).


>>> print response.content == response.text

>>> print str(response.content) == response.text

Using getline() with file input in C++

you can use getline from a file using this code. this code will take a whole line from the file. and then you can use a while loop to go all lines while (ins);

 ifstream ins(filename);
string s;
std::getline (ins,s);

Catching "Maximum request length exceeded"

There is no easy way to catch such exception unfortunately. What I do is either override the OnError method at the page level or the Application_Error in global.asax, then check if it was a Max Request failure and, if so, transfer to an error page.

protected override void OnError(EventArgs e) .....

private void Application_Error(object sender, EventArgs e)
    if (GlobalHelper.IsMaxRequestExceededException(this.Server.GetLastError()))

It's a hack but the code below works for me

const int TimedOutExceptionCode = -2147467259;
public static bool IsMaxRequestExceededException(Exception e)
    // unhandled errors = caught at global.ascx level
    // http exception = caught at page level

    Exception main;
    var unhandled = e as HttpUnhandledException;

    if (unhandled != null && unhandled.ErrorCode == TimedOutExceptionCode)
        main = unhandled.InnerException;
        main = e;

    var http = main as HttpException;

    if (http != null && http.ErrorCode == TimedOutExceptionCode)
        // hack: no real method of identifying if the error is max request exceeded as 
        // it is treated as a timeout exception
        if (http.StackTrace.Contains("GetEntireRawContent"))
            return true;

    return false;

Cannot implicitly convert type 'System.DateTime?' to 'System.DateTime'. An explicit conversion exists

The problem is that you are passing a nullable type to a non-nullable type.

You can do any of the following solution:

A. Declare your dt as nullable

DateTime? dt = dateTime;

B. Use Value property of the the DateTime? datetime

DateTime dt = datetime.Value;

C. Cast it

DateTime dt = (DateTime) datetime;

With jQuery, how do I capitalize the first letter of a text field while the user is still editing that field?

this will help you in - convert first letter of each word to uppercase

  /* convert First Letter UpperCase */
  $('#txtField').on('keyup', function (e) {
    var txt = $(this).val();
    $(this).val(txt.replace(/^(.)|\s(.)/g, function ($1) {
      return $1.toUpperCase( );

Example : this is a title case sentence -> This Is A Title Case Sentence

How to get rid of underline for Link component of React Router?

style={{ backgroundImage: "none" }}

Only this worked for me

Triggering a checkbox value changed event in DataGridView

I use the CellContentClick event, which makes sure the user clicked the checkbox. It DOES fire multiple times even if the user stays in the same cell. The one issue is that the Value does not get updated, and always returns "false" for unchecked. The trick is to use the .EditedFormattedValue property of the cell instead of the Value property. The EditedFormattedValue will track with the check mark and is what one wishes the Value had in it when the CellContentClick is fired.

No need for a timer, no need for any fancy stuff, just use CellContentClick event and inspect the EditedFormattedValue to tell what state the checkbox is going into / just went into. If EditedFormattedValue = true, the checkbox is getting checked.

Adding a collaborator to my free GitHub account?

It is pretty easy to add a collaborator to a free plan.

  1. Navigate to the repository on Github you wish to share with your collaborator.
  2. Click on the "Settings" tab on the right side of the menu at the top of the screen.
  3. On the new page, click the "Collaborators" menu item on the left side of the page.
  4. Start typing the new collaborator's GitHub username into the text box.
  5. Select the GitHub user from the list that appears below the text box.
  6. Click the "Add" button.

The added user should now be able to push to your repository on GitHub.

Writing a pandas DataFrame to CSV file

To delimit by a tab you can use the sep argument of to_csv:

df.to_csv(file_name, sep='\t')

To use a specific encoding (e.g. 'utf-8') use the encoding argument:

df.to_csv(file_name, sep='\t', encoding='utf-8')

How to secure the ASP.NET_SessionId cookie?

If the entire site uses HTTPS, your sessionId cookie is as secure as the HTTPS encryption at the very least. This is because cookies are sent as HTTP headers, and when using SSL, the HTTP headers are encrypted using the SSL when being transmitted.

How set the android:gravity to TextView from Java side in Android

You should use textView.setGravity(Gravity.CENTER_HORIZONTAL);.

Remember that using

LinearLayout.LayoutParams layoutParams =new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
layoutParams2.gravity = Gravity.BOTTOM | Gravity.CENTER_HORIZONTAL;

won't work. This will set the gravity for the widget and not for it's text.

How to convert the background to transparent?

If you want a command-line solution, you can use the ImageMagick convert utility:

convert input.png -transparent red output.png

HTML checkbox - allow to check only one checkbox

 $(function () {
     $('input[type=checkbox]').click(function () {
         var chks = document.getElementById('<%= chkRoleInTransaction.ClientID %>').getElementsByTagName('INPUT');
         for (i = 0; i < chks.length; i++) {
            chks[i].checked = false;
         if (chks.length > 1)
            $(this)[0].checked = true;

How can I read and parse CSV files in C++?

Another solution similar to Loki Astari's answer, in C++11. Rows here are std::tuples of a given type. The code scans one line, then scans until each delimiter, and then converts and dumps the value directly into the tuple (with a bit of template code).

for (auto row : csv<std::string, int, float>(file, ',')) {
    std::cout << "first col: " << std::get<0>(row) << std::endl;


  • quite clean and simple to use, only C++11.
  • automatic type conversion into std::tuple<t1, ...> via operator>>.

What's missing:

  • escaping and quoting
  • no error handling in case of malformed CSV.

The main code:

#include <iterator>
#include <sstream>
#include <string>

namespace csvtools {
    /// Read the last element of the tuple without calling recursively
    template <std::size_t idx, class... fields>
    typename std::enable_if<idx >= std::tuple_size<std::tuple<fields...>>::value - 1>::type
    read_tuple(std::istream &in, std::tuple<fields...> &out, const char delimiter) {
        std::string cell;
        std::getline(in, cell, delimiter);
        std::stringstream cell_stream(cell);
        cell_stream >> std::get<idx>(out);

    /// Read the @p idx-th element of the tuple and then calls itself with @p idx + 1 to
    /// read the next element of the tuple. Automatically falls in the previous case when
    /// reaches the last element of the tuple thanks to enable_if
    template <std::size_t idx, class... fields>
    typename std::enable_if<idx < std::tuple_size<std::tuple<fields...>>::value - 1>::type
    read_tuple(std::istream &in, std::tuple<fields...> &out, const char delimiter) {
        std::string cell;
        std::getline(in, cell, delimiter);
        std::stringstream cell_stream(cell);
        cell_stream >> std::get<idx>(out);
        read_tuple<idx + 1, fields...>(in, out, delimiter);

/// Iterable csv wrapper around a stream. @p fields the list of types that form up a row.
template <class... fields>
class csv {
    std::istream &_in;
    const char _delim;
    typedef std::tuple<fields...> value_type;
    class iterator;

    /// Construct from a stream.
    inline csv(std::istream &in, const char delim) : _in(in), _delim(delim) {}

    /// Status of the underlying stream
    /// @{
    inline bool good() const {
        return _in.good();
    inline const std::istream &underlying_stream() const {
        return _in;
    /// @}

    inline iterator begin();
    inline iterator end();

    /// Reads a line into a stringstream, and then reads the line into a tuple, that is returned
    inline value_type read_row() {
        std::string line;
        std::getline(_in, line);
        std::stringstream line_stream(line);
        std::tuple<fields...> retval;
        csvtools::read_tuple<0, fields...>(line_stream, retval, _delim);
        return retval;

/// Iterator; just calls recursively @ref csv::read_row and stores the result.
template <class... fields>
class csv<fields...>::iterator {
    csv::value_type _row;
    csv *_parent;
    typedef std::input_iterator_tag iterator_category;
    typedef csv::value_type         value_type;
    typedef std::size_t             difference_type;
    typedef csv::value_type *       pointer;
    typedef csv::value_type &       reference;

    /// Construct an empty/end iterator
    inline iterator() : _parent(nullptr) {}
    /// Construct an iterator at the beginning of the @p parent csv object.
    inline iterator(csv &parent) : _parent(parent.good() ? &parent : nullptr) {

    /// Read one row, if possible. Set to end if parent is not good anymore.
    inline iterator &operator++() {
        if (_parent != nullptr) {
            _row = _parent->read_row();
            if (!_parent->good()) {
                _parent = nullptr;
        return *this;

    inline iterator operator++(int) {
        iterator copy = *this;
        return copy;

    inline csv::value_type const &operator*() const {
        return _row;

    inline csv::value_type const *operator->() const {
        return &_row;

    bool operator==(iterator const &other) {
        return (this == &other) or (_parent == nullptr and other._parent == nullptr);
    bool operator!=(iterator const &other) {
        return not (*this == other);

template <class... fields>
typename csv<fields...>::iterator csv<fields...>::begin() {
    return iterator(*this);

template <class... fields>
typename csv<fields...>::iterator csv<fields...>::end() {
    return iterator();

I put a tiny working example on GitHub; I've been using it for parsing some numerical data and it served its purpose.

HSL to RGB color conversion

Unity3D C# Code from Mohsen's answer.

Here is the code from Mohsen's answer in C# targeted specifically for Unity3D. It was adapted from the C# answer given by Alec Thilenius above.

using UnityEngine;
using System.Collections;

public class ColorTools {

    /// <summary>
    /// Converts an HSL color value to RGB.
    /// Input: Vector4 ( X: [0.0, 1.0], Y: [0.0, 1.0], Z: [0.0, 1.0], W: [0.0, 1.0] )**strong text**
    /// Output: Color ( R: [0.0, 1.0], G: [0.0, 1.0], B: [0.0, 1.0], A: [0.0, 1.0] )
    /// </summary>
    /// <param name="hsl">Vector4 defining X = h, Y = s, Z = l, W = a. Ranges [0, 1.0]</param>
    /// <returns>RGBA Color. Ranges [0.0, 1.0]</returns>
    public static Color HslToRgba(Vector4 hsl)
        float r, g, b;

        if (hsl.y == 0.0f)
            r = g = b = hsl.z;
            var q = hsl.z < 0.5f ? hsl.z * (1.0f + hsl.y) : hsl.z + hsl.y - hsl.z * hsl.y;
            var p = 2.0f * hsl.z - q;
            r = HueToRgb(p, q, hsl.x + 1.0f / 3.0f);
            g = HueToRgb(p, q, hsl.x);
            b = HueToRgb(p, q, hsl.x - 1.0f / 3.0f);

        return new Color(r, g, b, hsl.w);

    // Helper for HslToRgba
    private static float HueToRgb(float p, float q, float t)
        if (t < 0.0f) t += 1.0f;
        if (t > 1.0f) t -= 1.0f;
        if (t < 1.0f / 6.0f) return p + (q - p) * 6.0f * t;
        if (t < 1.0f / 2.0f) return q;
        if (t < 2.0f / 3.0f) return p + (q - p) * (2.0f / 3.0f - t) * 6.0f;
        return p;

    /// <summary>
    /// Converts an RGB color value to HSL.
    /// Input: Color ( R: [0.0, 1.0], G: [0.0, 1.0], B: [0.0, 1.0], A: [0.0, 1.0] )
    /// Output: Vector4 ( X: [0.0, 1.0], Y: [0.0, 1.0], Z: [0.0, 1.0], W: [0.0, 1.0] )
    /// </summary>
    /// <param name="rgba"></param>
    /// <returns></returns>
    public static Vector4 RgbaToHsl(Color rgba)

        float max = (rgba.r > rgba.g && rgba.r > rgba.b) ? rgba.r : 
            (rgba.g > rgba.b) ? rgba.g : rgba.b;
        float min = (rgba.r < rgba.g && rgba.r < rgba.b) ? rgba.r : 
            (rgba.g < rgba.b) ? rgba.g : rgba.b;

        float h, s, l;
        h = s = l = (max + min) / 2.0f;

        if (max == min)
            h = s = 0.0f;
            float d = max - min;
            s = (l > 0.5f) ? d / (2.0f - max - min) : d / (max + min);

            if (rgba.r > rgba.g && rgba.r > rgba.b)
                h = (rgba.g - rgba.b) / d + (rgba.g < rgba.b ? 6.0f : 0.0f);

            else if (rgba.g > rgba.b)
                h = (rgba.b - rgba.r) / d + 2.0f;

                h = (rgba.r - rgba.g) / d + 4.0f;

            h /= 6.0f;

        return new Vector4(h, s, l, rgba.a);


Error message "Forbidden You don't have permission to access / on this server"

With Apache 2.2

Order Deny,Allow
Allow from all

With Apache 2.4

Require all granted


Is there a way to list open transactions on SQL Server 2000 database?

You can get all the information of active transaction by the help of below query

trans.session_id AS [SESSION ID],
ESes.host_name AS [HOST NAME],login_name AS [Login NAME],
trans.transaction_id AS [TRANSACTION ID], AS [TRANSACTION NAME],tas.transaction_begin_time AS [TRANSACTION 
tds.database_id AS [DATABASE ID], AS [DATABASE NAME]
FROM sys.dm_tran_active_transactions tas
JOIN sys.dm_tran_session_transactions trans
ON (trans.transaction_id=tas.transaction_id)
LEFT OUTER JOIN sys.dm_tran_database_transactions tds
ON (tas.transaction_id = tds.transaction_id )
LEFT OUTER JOIN sys.databases AS DBs
ON tds.database_id = DBs.database_id
LEFT OUTER JOIN sys.dm_exec_sessions AS ESes
ON trans.session_id = ESes.session_id
WHERE ESes.session_id IS NOT NULL

and it will give below similar result enter image description here

and you close that transaction by the help below KILL query by refering session id


Changing text of UIButton programmatically swift

Swift 3

let button: UIButton = UIButton()
button.frame = CGRect.init(x: view.frame.width/2, y: view.frame.height/2, width: 100, height: 100)
button.setTitle(“Title Button”, for: .normal)

For each row return the column name of the largest value

Here is an answer that works with data.table and is simpler. This assumes your data.table is named yourDF:

j1 <- max.col(yourDF[, .(V1, V2, V3, V4)], "first")
yourDF$newCol <- c("V1", "V2", "V3", "V4")[j1]

Replace ("V1", "V2", "V3", "V4") and (V1, V2, V3, V4) with your column names

Android Bitmap to Base64 String

All of these answers are inefficient as they needlessly decode to a bitmap and then recompress the bitmap. When you take a photo on Android, it is stored as a jpeg in the temp file you specify when you follow the android docs.

What you should do is directly convert that file to a Base64 string. Here is how to do that in easy copy-paste (in Kotlin). Note you must close the base64FilterStream to truly flush its internal buffer.

fun convertImageFileToBase64(imageFile: File): String {

    return FileInputStream(imageFile).use { inputStream ->
        ByteArrayOutputStream().use { outputStream ->
            Base64OutputStream(outputStream, Base64.DEFAULT).use { base64FilterStream ->

As a bonus, your image quality should be slightly improved, due to bypassing the re-compressing.

How to view file history in Git?

TortoiseGit also provides a command line tool to do see the history of a file. Using PowerShell:

C:\Program` Files\TortoiseGit\bin\TortoiseGitProc.exe /command:log /path:"c:\path\to\your\file.txt"

Implement specialization in ER diagram

So I assume your permissions table has a foreign key reference to admin_accounts table. If so because of referential integrity you will only be able to add permissions for account ids exsiting in the admin accounts table. Which also means that you wont be able to enter a user_account_id [assuming there are no duplicates!]

Force drop mysql bypassing foreign key constraint

Drop database exist in all versions of MySQL. But if you want to keep the table structure, here is an idea

mysqldump --no-data --add-drop-database --add-drop-table -hHOSTNAME -uUSERNAME -p > dump.sql

This is a program, not a mysql command

Then, log into mysql and

source dump.sql;

How to load image (and other assets) in Angular an project?

Angular-cli includes the assets folder in the build options by default. I got this issue when the name of my images had spaces or dashes. For example :

  • 'my-image-name.png' should be 'myImageName.png'
  • 'my image name.png' should be 'myImageName.png'

If you put the image in the assets/img folder, then this line of code should work in your templates :

<img alt="My image name" src="./assets/img/myImageName.png">

If the issue persist just check if your Angular-cli config file and be sure that your assets folder is added in the build options.

How to add a ScrollBar to a Stackpanel

It works like this:

<ScrollViewer VerticalScrollBarVisibility="Visible" HorizontalScrollBarVisibility="Disabled" Width="340" HorizontalAlignment="Left" Margin="12,0,0,0">
        <StackPanel Name="stackPanel1" Width="311">


TextBox tb = new TextBox();
tb.TextChanged += new TextChangedEventHandler(TextBox_TextChanged);

File Upload ASP.NET MVC 3.0

Since i have found issue uploading file in IE browser i would suggest to handle it like this.


@using (Html.BeginForm("UploadFile", "Home", FormMethod.Post, new { enctype = "multipart/form-data" }))
    <input type="file" name="file" />
    <input type="submit" value="Submit" />


public class HomeController : Controller
    public ActionResult UploadFile()
        return View();

    public ActionResult UploadFile(MyModal Modal)
            string DocumentName = string.Empty;
            string Description = string.Empty;

            if (!String.IsNullOrEmpty(Request.Form["DocumentName"].ToString()))
                DocumentName = Request.Form["DocumentName"].ToString();
            if (!String.IsNullOrEmpty(Request.Form["Description"].ToString()))
                Description = Request.Form["Description"].ToString();

            if (!String.IsNullOrEmpty(Request.Form["FileName"].ToString()))
                UploadedDocument = Request.Form["FileName"].ToString();

            HttpFileCollectionBase files = Request.Files;

            string filePath = Server.MapPath("~/Root/Documents/");
            if (!(Directory.Exists(filePath)))
            for (int i = 0; i < files.Count; i++)
                HttpPostedFileBase file = files[i];
                // Checking for Internet Explorer  
                if (Request.Browser.Browser.ToUpper() == "IE" || Request.Browser.Browser.ToUpper() == "INTERNETEXPLORER")
                    string[] testfiles = file.FileName.Split(new char[] { '\\' });
                    fname = testfiles[testfiles.Length - 1];
                    UploadedDocument = fname;
                    fname = file.FileName;
                    UploadedDocument = file.FileName;
                return RedirectToAction("List", "Home");

SQL Server 2008 R2 Express permissions -- cannot create database or modify users

Coming late to the party, but I found this fantastic step-by-step guide on getting control of your SQLExpress instance if you don't have your sa password. I used this process to not only reset my sa password, but I also added my domain account to all the available server roles. I can now create databases, alter logins, do bulk operations, backups/restores, etc using my normal login.

To summarize, you use SQL Server Configuration Manager to put your instance into single-user mode. This elevates you to sysadmin when you connect, allowing you the ability to set everything up.

Edit: I've copied the steps below - kudos to the original author of the link above.

  1. Log on to the computer as an Administrator (or Any user with administrator privileges)
  2. Open "SQL Server Configuration Manager"
  3. Click "SQL Server Services" on the left pane
  4. Stop "SQL Server" and "SQL Server Agent" instance on the right pane if it is running
  5. Run the SQL Express in single-user mode by right clicking on "SQL Server" instance -> Properties (on the right pane of SQL Server Configuration Manager).
  6. Click Advanced Tab, and look for "Startup Parameters". Change the "Startup Parameters" so that the new value will be -m; (without the <>) example: from: -dc:\Program Files\Microsoft SQL.............(til end of string) to: -m;-dc:\Program Files\Microsoft SQL.............(til end of string)
  7. Start the SQL Server
  8. Open your MS SQL Server Management Studio and log on to the SQL server with "Windows Authentication" as the authentication mode. Since we have the SQL Server running on single user mode, and you are logged on to the computer with Administrator privileges, you will have a "sysadmin" access to the database.
  9. Expand the "Security" node on MS SQL Server Management Studio on the left pane
  10. Expand the "Logins" node
  11. Double-click the 'sa' login
  12. Change the password by entering a complex password if "Enforce password policy" is ticked, otherwise, just enter any password.
  13. Make sure that "sa" Account is "enabled" by clicking on Status on the left pane. Set the radio box under "Login" to "Enabled"
  14. Click "OK"
  15. Back on the main window of MS SQL Server Management Studio, verify if SQL Server Authentication is used by right clicking on the top most node in the left pane (usually ".\SQLEXPRESS (SQL Server )") and choosing properties.
  16. Click "Security" in the left pane and ensure that "SQL Server and Windows Authentication mode" is the one selected under "Server authentication"
  17. Click "OK"
  18. Disconnect from MS SQL Server Management Studio
  19. Open "Sql Server Configuration Manager" again and stop the SQL Server instance.
  20. Right-click on SQL Server instance and click on "Advanced" tab. Again look for "Startup Parameters" and remove the "-m;" that you added earlier.
  21. Click "OK" and start the SQL Server Instance again
  22. You should now be able to log on as "sa" using the new password that you have set in step 12.

CSS 100% height with padding/margin

Another solution: You can use percentage units for margins as well as sizes. For example:

.fullWidthPlusMargin {
    width: 98%;
    margin: 1%;

The main issue here is that the margins will increase/decrease slightly with the size of the parent element. Presumably the functionality you would prefer is for the margins to stay constant and the child element to grow/shrink to fill changes in spacing. So, depending on how tight you need your display to be, that could be problematic. (I'd also go for a smaller margin, like 0.3%).

Does Spring Data JPA have any way to count entites using method name resolving?

Working example

public interface TenantRepository extends JpaRepository< Tenant, Long > {
    List<Tenant>findByTenantName(String tenantName,Pageable pageRequest);
    long countByTenantName(String tenantName);

Calling from DAO layer

public long countByTenantName(String tenantName) {
    return repository.countByTenantName(tenantName);

Writing an input integer into a cell

When asking a user for a response to put into a cell using the InputBox method, there are usually three things that can happen¹.

  1. The user types something in and clicks OK. This is what you expect to happen and you will receive input back that can be returned directly to a cell or a declared variable.
  2. The user clicks Cancel, presses Esc or clicks × (Close). The return value is a boolean False. This should be accounted for.
  3. The user does not type anything in but clicks OK regardless. The return value is a zero-length string.

If you are putting the return value into a cell, your own logic stream will dictate what you want to do about the latter two scenarios. You may want to clear the cell or you may want to leave the cell contents alone. Here is how to handle the various outcomes with a variant type variable and a Select Case statement.

    Dim returnVal As Variant

    returnVal = InputBox(Prompt:="Type a value:", Title:="Test Data")

    'if the user clicked Cancel, Close or Esc the False
    'is translated to the variant as a vbNullString
    Select Case True
        Case Len(returnVal) = 0
            'no value but user clicked OK - clear the target cell
        Case Else
            'returned a value with OK, save it
            Range("A2") = returnVal
    End Select

¹ There is a fourth scenario when a specific type of InputBox method is used. An InputBox can return a formula, cell range error or array. Those are special cases and requires using very specific syntax options. See the supplied link for more.

Use of "this" keyword in formal parameters for static methods in C#

Scott Gu's quoted blog post explains it nicely.

For me, the answer to the question is in the following statement in that post:

Note how the static method above has a "this" keyword before the first parameter argument of type string. This tells the compiler that this particular Extension Method should be added to objects of type "string". Within the IsValidEmailAddress() method implementation I can then access all of the public properties/methods/events of the actual string instance that the method is being called on, and return true/false depending on whether it is a valid email or not.

How to get current formatted date dd/mm/yyyy in Javascript and append it to an input

Use the DOM's getElementByid method:

document.getElementById("DATE").value = "your date";

A date can be made with the Date class:

d = new Date();

(Protip: install a javascript console such as in Chrome or Firefox' Firebug extension. It enables you to play with the DOM and Javascript)

Found a swap file by the name

More info... Some times .swp files might be holded by vm that was running in backgroung. You may see permission denied message when try to delete the files.

Check and kill process vm

Apply a theme to an activity in Android?

To set it programmatically in

public void onCreate(Bundle savedInstanceState) {


  setTheme(; // (for Custom theme)
  setTheme(; // (for Android Built In Theme)


To set in Application scope in Manifest.xml (all activities):


To set in Activity scope in Manifest.xml (single activity):


To build a custom theme, you will have to declare theme in themes.xml file, and set styles in styles.xml file.

How to check the differences between local and github before the pull

If you're not interested in the details that git diff outputs you can just run git cherry which will output a list of commits your remote tracking branch has ahead of your local branch.

For example:

git fetch origin
git cherry master origin/master

Will output something like :

+ 2642039b1a4c4d4345a0d02f79ccc3690e19d9b1
+ a4870f9fbde61d2d657e97b72b61f46d1fd265a9

Indicates that there are two commits in my remote tracking branch that haven't been merged into my local branch.

This also works the other way :

    git cherry origin/master master

Will show you a list of local commits that you haven't pushed to your remote repository yet.

How to set the matplotlib figure default size in ipython notebook?

Just for completeness, this also works

from IPython.core.pylabtools import figsize
figsize(14, 7)

It is a wrapper aroung the rcParams solution

Download JSON object as a file from browser

The download property of links is new and not is supported in Internet Explorer (see the compatibility table here). For a cross-browser solution to this problem I would take a look at FileSaver.js

How Do I Make Glyphicons Bigger? (Change Size?)

Yes, and basically you can also use inline style:

<span style="font-size: 15px" class="glyphicon glyphicon-cog"></span>

How to inherit constructors?

Yes, you have to copy all 387 constructors. You can do some reuse by redirecting them:

  public Bar(int i): base(i) {}
  public Bar(int i, int j) : base(i, j) {}

but that's the best you can do.

How to obtain the number of CPUs/cores in Linux from the command line?

You can also use Python! To get the number of physical cores:

$ python -c "import psutil; print(psutil.cpu_count(logical=False))"

To get the number of hyperthreaded cores:

$ python -c "import psutil; print(psutil.cpu_count(logical=True))"

How to get the current loop index when using Iterator?

Here's a way to do it using your own variable and keeping it concise:

List<String> list = Arrays.asList("zero", "one", "two");

int i = 0;
for (Iterator<String> it = list.iterator(); it.hasNext(); i++) {
    String s =;
    System.out.println(i + ": " + s);

Output (you guessed it):

0: zero
1: one
2: two

The advantage is that you don't increment your index within the loop (although you need to be careful to only call Iterator#next once per loop - just do it at the top).

CSS strikethrough different color from text?

Here is a sample jQuery implementation – thanks to gojomo's answer and utype's suggestion (+1 for both)

  // Special price strike-out text
  // Usage:
  //   Normally:    <span class='price'>$59</span>
  //   On special:  <span class='price' special='$29'>$59</span>
  $(".price[special]").each(function() {
    var originalPrice = $(this).text();
    $(this).html('<strike><span>' + originalPrice +'</span></strike> ' + $(this).attr('special'))

The CSS for that could be

.price strike, .price.special { color: Red; }
.price strike span { color: Black; }

Setting active profile and config location from command line in spring boot

There are two different ways you can add/override spring properties on the command line.

Option 1: Java System Properties (VM Arguments)

It's important that the -D parameters are before your application.jar otherwise they are not recognized.

java -jar application.jar

Option 2: Program arguments

java -jar application.jar --spring.config.location=c:\config

How do I use Maven through a proxy?

The above postings helped in resolving my problem. In addition to the above I had to make the following changes to make it work :

  • Modified Maven's JRE net settings(\jre\lib\ to use system proxy setting.

    https.proxyHost=proxy DNS
    https.proxyPort=proxy port
  • Included proxy server settings in settings.xml. I did not provide username and password settings as to use NTLM authentication.

How to set the min and max height or width of a Frame?

A workaround - at least for the minimum size: You can use grid to manage the frames contained in root and make them follow the grid size by setting sticky='nsew'. Then you can use root.grid_rowconfigure and root.grid_columnconfigure to set values for minsize like so:

from tkinter import Frame, Tk

class MyApp():
    def __init__(self):
        self.root = Tk()

        self.my_frame_red = Frame(self.root, bg='red')
        self.my_frame_red.grid(row=0, column=0, sticky='nsew')

        self.my_frame_blue = Frame(self.root, bg='blue')
        self.my_frame_blue.grid(row=0, column=1, sticky='nsew')

        self.root.grid_rowconfigure(0, minsize=200, weight=1)
        self.root.grid_columnconfigure(0, minsize=200, weight=1)
        self.root.grid_columnconfigure(1, weight=1)


if __name__ == '__main__':
    app = MyApp()

But as Brian wrote (in 2010 :D) you can still resize the window to be smaller than the frame if you don't limit its minsize.

What should a Multipart HTTP request with multiple files look like?

EDIT: I am maintaining a similar, but more in-depth answer at:

To see exactly what is happening, use nc -l and an user agent like a browser or cURL.

Save the form to an .html file:

<form action="http://localhost:8000" method="post" enctype="multipart/form-data">
  <p><input type="text" name="text" value="text default">
  <p><input type="file" name="file1">
  <p><input type="file" name="file2">
  <p><button type="submit">Submit</button>

Create files to upload:

echo 'Content of a.txt.' > a.txt
echo '<!DOCTYPE html><title>Content of a.html.</title>' > a.html


nc -l localhost 8000

Open the HTML on your browser, select the files and click on submit and check the terminal.

nc prints the request received. Firefox sent:

Host: localhost:8000
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:29.0) Gecko/20100101 Firefox/29.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Cookie: __atuvc=34%7C7; permanent=0; _gitlab_session=226ad8a0be43681acf38c2fab9497240; __profilin=p%3Dt; request_method=GET
Connection: keep-alive
Content-Type: multipart/form-data; boundary=---------------------------9051914041544843365972754266
Content-Length: 554

Content-Disposition: form-data; name="text"

text default
Content-Disposition: form-data; name="file1"; filename="a.txt"
Content-Type: text/plain

Content of a.txt.

Content-Disposition: form-data; name="file2"; filename="a.html"
Content-Type: text/html

<!DOCTYPE html><title>Content of a.html.</title>


Aternativelly, cURL should send the same POST request as your a browser form:

nc -l localhost 8000
curl -F "text=default" -F "[email protected]" -F "[email protected]" localhost:8000

You can do multiple tests with:

while true; do printf '' | nc -l localhost 8000; done

a tag as a submit button?

Try something like below

 <a href="#" onclick="this.forms['formName'].submit()">Submit</a> 

Convert string date to timestamp in Python

A simple function to get UNIX Epoch time.

NOTE: This function assumes the input date time is in UTC format (Refer to comments here).

def utctimestamp(ts: str, DATETIME_FORMAT: str = "%d/%m/%Y"):
    import datetime, calendar
    ts = datetime.datetime.utcnow() if ts is None else datetime.datetime.strptime(ts, DATETIME_FORMAT)
    return calendar.timegm(ts.utctimetuple())


>>> utctimestamp("01/12/2011")
>>> utctimestamp("2011-12-01", "%Y-%m-%d")

How to get a div to resize its height to fit container?

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<style type="text/css">
#top, #bottom {
    height: 100px;
    width: 100%;
    position: relative;
#container {
    overflow: hidden;
    position: relative;
    width: 100%;
#container .left {
    height: 550px;
    width: 55%;
    position: relative;
    float: left;
    background-color: #3399FF;
#container .right {
    height: 100%;
    position: absolute;
    right: 0;
    left: 55%;
    bottom: 0px;
    top: 0px;
    background-color: #3366CC;

<div id="top"></div>
<div id="container">
  <div class="left"></div>
  <div class="right"></div>
<div id="bottom"></div>

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.testing.models.Account

I had a similar exception (but different problem) - java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to org.bson.Document , and fortunately it's solved easier:

Instead of

List<Document> docs = obj.get("documents");
Document doc = docs.get(0)

which gives error on second line, One can use

List<Document> docs = obj.get("documents");
Document doc = new Document(docs.get(0));

How do I revert an SVN commit?

svn merge -r 1944:1943 . should revert the changes of r1944 in your working copy. You can then review the changes in your working copy (with diff), but you'd need to commit in order to apply the revert into the repository.

Fast way to discover the row count of a table in PostgreSQL

For SQL Server (2005 or above) a quick and reliable method is:

SELECT SUM (row_count)
FROM sys.dm_db_partition_stats
WHERE object_id=OBJECT_ID('MyTableName')   
AND (index_id=0 or index_id=1);

Details about sys.dm_db_partition_stats are explained in MSDN

The query adds rows from all parts of a (possibly) partitioned table.

index_id=0 is an unordered table (Heap) and index_id=1 is an ordered table (clustered index)

Even faster (but unreliable) methods are detailed here.

CSS - display: none; not working

This is because the inline style display:block is overwriting your CSS. You'll need to either remove this inline style or use:

#tfl {
  display: none !important;

This overrides inline styles. Note that using !important is generally not recommended unless it's a last resort.

NameError: global name 'unicode' is not defined - in Python 3

One can replace unicode with u''.__class__ to handle the missing unicode class in Python 3. For both Python 2 and 3, you can use the construct

isinstance(unicode_or_str, u''.__class__)


type(unicode_or_str) == type(u'')

Depending on your further processing, consider the different outcome:

Python 3

>>> isinstance('text', u''.__class__)
>>> isinstance(u'text', u''.__class__)

Python 2

>>> isinstance(u'text', u''.__class__)
>>> isinstance('text', u''.__class__)

How to revert a "git rm -r ."?

To regain some single files or folders one may use the following

git reset -- path/to/file
git checkout -- path/to/file

This will first recreate the index entries for path/to/file and recreate the file as it was in the last commit, i.e.HEAD.

Hint: one may pass a commit hash to both commands to recreate files from an older commit. See git reset --help and git checkout --help for details.

Finding an item in a List<> using C#

For .NET 2.0:

list.Find(delegate(Item i) { return i.Property == someValue; });

Cannot make file No such file or directory

File.isFile() is false if the file / directory does not exist, so you can't use it to test whether you're trying to create a directory. But that's not the first issue here.

The issue is that the intermediate directories don't exist. You want to call f.mkdirs() first.

Django - filtering on foreign key properties

student_user = User.objects.get(id=user_id)
available_subjects = Subject.objects.exclude(subject_grade__student__user=student_user) # My ans
enrolled_subjects = SubjectGrade.objects.filter(student__user=student_user)
context.update({'available_subjects': available_subjects, 'student_user': student_user, 
                'request':request, 'enrolled_subjects': enrolled_subjects})

In my application above, i assume that once a student is enrolled, a subject SubjectGrade instance will be created that contains the subject enrolled and the student himself/herself.

Subject and Student User model is a Foreign Key to the SubjectGrade Model.

In "available_subjects", i excluded all the subjects that are already enrolled by the current student_user by checking all subjectgrade instance that has "student" attribute as the current student_user

PS. Apologies in Advance if you can't still understand because of my explanation. This is the best explanation i Can Provide. Thank you so much

Best way to specify whitespace in a String.Split operation

So don't copy and paste! Extract a function to do your splitting and reuse it.

public static string[] SplitWhitespace (string input)
    char[] whitespace = new char[] { ' ', '\t' };
    return input.Split(whitespace);

Code reuse is your friend.

Best way to test exceptions with Assert to ensure they will be thrown

As an alternative to using ExpectedException attribute, I sometimes define two helpful methods for my test classes:

AssertThrowsException() takes a delegate and asserts that it throws the expected exception with the expected message.

AssertDoesNotThrowException() takes the same delegate and asserts that it does not throw an exception.

This pairing can be very useful when you want to test that an exception is thrown in one case, but not the other.

Using them my unit test code might look like this:

ExceptionThrower callStartOp = delegate(){ testObj.StartOperation(); };

// Check exception is thrown correctly...
AssertThrowsException(callStartOp, typeof(InvalidOperationException), "StartOperation() called when not ready.");

testObj.Ready = true;

// Check exception is now not thrown...

Nice and neat huh?

My AssertThrowsException() and AssertDoesNotThrowException() methods are defined on a common base class as follows:

protected delegate void ExceptionThrower();

/// <summary>
/// Asserts that calling a method results in an exception of the stated type with the stated message.
/// </summary>
/// <param name="exceptionThrowingFunc">Delegate that calls the method to be tested.</param>
/// <param name="expectedExceptionType">The expected type of the exception, e.g. typeof(FormatException).</param>
/// <param name="expectedExceptionMessage">The expected exception message (or fragment of the whole message)</param>
protected void AssertThrowsException(ExceptionThrower exceptionThrowingFunc, Type expectedExceptionType, string expectedExceptionMessage)
        Assert.Fail("Call did not raise any exception, but one was expected.");
    catch (NUnit.Framework.AssertionException)
        // Ignore and rethrow NUnit exception
    catch (Exception ex)
        Assert.IsInstanceOfType(expectedExceptionType, ex, "Exception raised was not the expected type.");
        Assert.IsTrue(ex.Message.Contains(expectedExceptionMessage), "Exception raised did not contain expected message. Expected=\"" + expectedExceptionMessage + "\", got \"" + ex.Message + "\"");

/// <summary>
/// Asserts that calling a method does not throw an exception.
/// </summary>
/// <remarks>
/// This is typically only used in conjunction with <see cref="AssertThrowsException"/>. (e.g. once you have tested that an ExceptionThrower
/// method throws an exception then your test may fix the cause of the exception and then call this to make sure it is now fixed).
/// </remarks>
/// <param name="exceptionThrowingFunc">Delegate that calls the method to be tested.</param>
protected void AssertDoesNotThrowException(ExceptionThrower exceptionThrowingFunc)
    catch (NUnit.Framework.AssertionException)
        // Ignore and rethrow any NUnit exception
    catch (Exception ex)
        Assert.Fail("Call raised an unexpected exception: " + ex.Message);

javax.websocket client simple example

Have a look at this Java EE 7 examples from Arun Gupta.

I forked it on github.


 * @author Arun Gupta
public class Client {

    final static CountDownLatch messageLatch = new CountDownLatch(1);

    public static void main(String[] args) {
        try {
            WebSocketContainer container = ContainerProvider.getWebSocketContainer();
            String uri = "ws://";
            System.out.println("Connecting to " + uri);
            container.connectToServer(MyClientEndpoint.class, URI.create(uri));
            messageLatch.await(100, TimeUnit.SECONDS);
        } catch (DeploymentException | InterruptedException | IOException ex) {
            Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);


 * @author Arun Gupta
public class MyClientEndpoint {
    public void onOpen(Session session) {
        System.out.println("Connected to endpoint: " + session.getBasicRemote());
        try {
            String name = "Duke";
            System.out.println("Sending message to endpoint: " + name);
        } catch (IOException ex) {
            Logger.getLogger(MyClientEndpoint.class.getName()).log(Level.SEVERE, null, ex);

    public void processMessage(String message) {
        System.out.println("Received message in client: " + message);

    public void processError(Throwable t) {

Export and import table dump (.sql) using pgAdmin

An another way, you can do it easily with CMD on Windows

Put your installed version (mine is 11).

cd C:\Program Files\PostgreSQL\11\bin\

and run simple query

psql -U <postgre_username> -d <db_name> < <C:\path\data_dump.sql>

enter password then wait the final console message.

Chart creating dynamically. in .net, c#

Try to include these lines on your code, after mych.Visible = true;:

ChartArea chA = new ChartArea();

Javascript: Fetch DELETE and PUT requests

Ok, here is a fetch DELETE example too:

fetch('' + id, {
  method: 'DELETE',
.then(res => res.text()) // or res.json()
.then(res => console.log(res))

Regex for password must contain at least eight characters, at least one number and both lower and uppercase letters and special characters

var strongRegex = new RegExp("^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#\$%\^&\*])(?=.{8,})");
var mediumRegex = new RegExp("^(((?=.*[a-z])(?=.*[A-Z]))|((?=.*[a-z])(?=.*[0-9]))|((?=.*[A-Z])(?=.*[0-9])))(?=.{6,})");

Best For javascript