Programs & Examples On #Latent semantic indexing

Latent semantic indexing is an indexing and retrieval method.

Can we overload the main method in Java?

Yes,u can overload main method but the interpreter will always search for the correct main method syntax to begin the execution.. And yes u have to call the overloaded main method with the help of object.

class Sample{
public void main(int a,int b){
System.out.println("The value of a is "  +a);
public static void main(String args[]){
System.out.println("We r in main method");
Sample obj=new Sample();
public static void main(int c){
System.out.println("The value of c  is"  +c);

The output of the program is:
We r in main method
The value of a is 5
The value of c is 3

How do I fix the indentation of an entire file in Vi?

:set paste is your friend I use putty and end up copying code between windows. Before I was turned on to :set paste (and :set nopaste) copy/paste gave me fits for that very reason.

How to create a batch file to run cmd as administrator

Here's a more simple version of essentially the same file.

@echo off
break off
title C:\Windows\system32\cmd.exe

set /p cmd=C:\Enter Command:

goto cmd

Visual Studio Expand/Collapse keyboard shortcuts

I have always wanted Visual Studio to include an option to just collapse / expand the regions. I have the following macros which will do just that.

Imports EnvDTE
Imports System.Diagnostics
' Macros for improving keyboard support for "#region ... #endregion"
Public Module CollapseExpandRegions
' Expands all regions in the current document
  Sub ExpandAllRegions()

    Dim objSelection As TextSelection ' Our selection object

    DTE.SuppressUI = True ' Disable UI while we do this
    objSelection = DTE.ActiveDocument.Selection() ' Hook up to the ActiveDocument's selection
    objSelection.StartOfDocument() ' Shoot to the start of the document

    ' Loop through the document finding all instances of #region. This action has the side benefit
    ' of actually zooming us to the text in question when it is found and ALSO expanding it since it
    ' is an outline.
    Do While objSelection.FindText("#region", vsFindOptions.vsFindOptionsMatchInHiddenText)
        ' This next command would be what we would normally do *IF* the find operation didn't do it for us.
    objSelection.StartOfDocument() ' Shoot us back to the start of the document
    DTE.SuppressUI = False ' Reenable the UI

    objSelection = Nothing ' Release our object

  End Sub

  ' Collapses all regions in the current document
  Sub CollapseAllRegions()
    Dim objSelection As TextSelection ' Our selection object

    ExpandAllRegions() ' Force the expansion of all regions

    DTE.SuppressUI = True ' Disable UI while we do this
    objSelection = DTE.ActiveDocument.Selection() ' Hook up to the ActiveDocument's selection
    objSelection.EndOfDocument() ' Shoot to the end of the document

    ' Find the first occurence of #region from the end of the document to the start of the document. Note:
    ' Note: Once a #region is "collapsed" .FindText only sees it's "textual descriptor" unless
    ' vsFindOptions.vsFindOptionsMatchInHiddenText is specified. So when a #region "My Class" is collapsed,
    ' .FindText would subsequently see the text 'My Class' instead of '#region "My Class"' for the subsequent
    ' passes and skip any regions already collapsed.
    Do While (objSelection.FindText("#region", vsFindOptions.vsFindOptionsBackwards))
        DTE.ExecuteCommand("Edit.ToggleOutliningExpansion") ' Collapse this #region
        'objSelection.EndOfDocument() ' Shoot back to the end of the document for
        ' another pass.
    objSelection.StartOfDocument() ' All done, head back to the start of the doc
    DTE.SuppressUI = False ' Reenable the UI

    objSelection = Nothing ' Release our object

  End Sub
End Module

EDIT: There is now a shortcut called Edit.ToggleOutliningExpansion (Ctrl+M, Ctrl+M) for doing just that.

Determine if variable is defined in Python

except NameError:
    print("well, it WASN'T defined after all!")
    print("sure, it was defined.")

How to run TypeScript files from command line?

You can use esrun that executes almost instantly a typescript file.

Advantages over ts-node:

  • very fast (use esbuild),
  • you can use ES modules without having to add "types": "module" to your package.json,
  • you can also use it as a replacement to Node to execute modern Javascript with ES modules, decorators, class fields, etc...

Setting Icon for wpf application (VS 08)

Note: (replace file.ico with your actual icon filename)

  1. Add the icon to the project with build action of "Resource".
  2. In the Project Properties, set the Application Icon to file.ico
  3. In the main Window XAML set: Icon=".\file.ico" on the Window

CURL to access a page that requires a login from a different page

Also you might want to log in via browser and get the command with all headers including cookies:

Open the Network tab of Developer Tools, log in, navigate to the needed page, use "Copy as cURL".


Javascript switch vs. if...else if...else

  1. Workbenching might result some very small differences in some cases but the way of processing is browser dependent anyway so not worth bothering
  2. Because of different ways of processing
  3. You can't call it a browser if the behavior would be different anyhow

Add & delete view from Layout

Use ViewStub and specify the layout of the view you want to toggle. To view:

mViewStub.setVisibility(View.VISIBLE) or mViewStub.inflate();

To disappear:


Using Html.ActionLink to call action on different controller

I would recommend writing these helpers using named parameters for the sake of clarity as follows:

    linkText: "Details",
    actionName: "Details",
    controllerName: "Product",
    routeValues: new {
        id = item.ID
    htmlAttributes: null

What is the difference between String.slice and String.substring?

substr: It's providing us to fetch part of the string based on specified index. syntax of substr- string.substr(start,end) start - start index tells where the fetching start. end - end index tells upto where string fetches. It's optional.

slice: It's providing to fetch part of the string based on the specified index. It's allows us to specify positive and index. syntax of slice - string.slice(start,end) start - start index tells where the fetching start.It's end - end index tells upto where string fetches. It's optional. In 'splice' both start and end index helps to take positive and negative index.

sample code for 'slice' in string

var str="Javascript";

output: crip

sample code for 'substring' in string

var str="Javascript";

output: avas

[*Note: negative indexing starts at the end of the string.]

Proper usage of .net MVC Html.CheckBoxFor

I had trouble getting this to work and added another solution for anyone wanting/ needing to use FromCollection.

Instead of:

@Html.CheckBoxFor(model => true, item.TemplateId) 

Format html helper like so:

@Html.CheckBoxFor(model => model.SomeProperty, new { @class = "form-control", Name = "SomeProperty"})

Then in the viewmodel/model wherever your logic is:

public void Save(FormCollection frm)
    // to do instantiate object.

    instantiatedItem.SomeProperty = (frm["SomeProperty"] ?? "").Equals("true", StringComparison.CurrentCultureIgnoreCase);

    // to do and save changes in database.

How to convert time milliseconds to hours, min, sec format in JavaScript?

// The following is written in Typescript, should be easy to translate to JS

function humanReadableDuration(msDuration: int): string {
    const h = Math.floor(msDuration / 1000 / 60 / 60);
    const m = Math.floor((msDuration / 1000 / 60 / 60 - h) * 60);
    const s = Math.floor(((msDuration / 1000 / 60 / 60 - h) * 60 - m) * 60);

    // To get time format 00:00:00
    const seconds: string = s < 10 ? `0${s}` : `${s}`;
    const minutes: string = m < 10 ? `0${m}` : `${m}`;
    const hours: string = h < 10 ? `0${h}` : `${h}`;

    return `${hours}h ${minutes}m ${seconds}s`;

php $_GET and undefined index

I was having the same problem in localhost with xampp. Now I'm using this combination of parameters:

// Report all errors except E_NOTICE
// This is the default value set in php.ini
error_reporting(E_ALL ^ E_NOTICE);

How can I force users to access my page over HTTPS instead of HTTP?

I have been through many solutions with checking the status of $_SERVER[HTTPS] but seems like it is not reliable because sometimes it does not set or set to on, off, etc. causing the script to internal loop redirect.

Here is the most reliable solution if your server supports $_SERVER[SCRIPT_URI]

if (stripos(substr($_SERVER[SCRIPT_URI], 0, 5), "https") === false) {
    echo "<meta http-equiv='refresh' content='0; url=https://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]'>";

Please note that depending on your installation, your server might not support $_SERVER[SCRIPT_URI] but if it does, this is the better script to use.

You can check here: Why do some PHP installations have $_SERVER['SCRIPT_URI'] and others not

What JSON library to use in Scala?

Lift-json is at version 2.6 and it works really well (and is also very well supported, the maintainer is always ready to fix any bugs users may find. You can find examples using it on the github repository

The maintainer (Joni Freeman) is always reachable on the Lift mailing list. There are also other users on the mailing list who are very helpful as well.

As @Alexey points out, if you want to use the library with other Scala version, say 2.11.x, change scalaVersion and use %% as follows:

scalaVersion := "2.11.5" 

"net.liftweb" %% "lift-json" % "2.6"

You can check the site to find out the latest version as time goes by.

How to return 2 values from a Java method?

Instead of returning an array that contains the two values or using a generic Pair class, consider creating a class that represents the result that you want to return, and return an instance of that class. Give the class a meaningful name. The benefits of this approach over using an array are type safety and it will make your program much easier to understand.

Note: A generic Pair class, as proposed in some of the other answers here, also gives you type safety, but doesn't convey what the result represents.

Example (which doesn't use really meaningful names):

final class MyResult {
    private final int first;
    private final int second;

    public MyResult(int first, int second) {
        this.first = first;
        this.second = second;

    public int getFirst() {
        return first;

    public int getSecond() {
        return second;

// ...

public static MyResult something() {
    int number1 = 1;
    int number2 = 2;

    return new MyResult(number1, number2);

public static void main(String[] args) {
    MyResult result = something();
    System.out.println(result.getFirst() + result.getSecond());

How to add an element to Array and shift indexes?

Have a look at commons. It uses arrayCopy(), but has nicer syntax. To those answering with the element-by-element code: if this isn't homework, that's trivial and the interesting answer is the one that promotes reuse. To those who propose lists: probably readers know about that too and performance issues should be mentioned.

Using psql to connect to PostgreSQL in SSL mode

psql --set=sslmode=require -h localhost -p 2345 -U thirunas \
-d postgres -f test_schema.ddl

Another Example for securely connecting to Azure's managed Postgres database:

psql --file=product_data.sql --port=5432 \
--username=postgres@postgres-esprit --dbname=product_data \
--set=sslmode=verify-full --set=sslrootcert=/opt/ssl/BaltimoreCyberTrustRoot.crt.pem

How to retry image pull in a kubernetes Pods?

If the Pod is part of a Deployment or Service, deleting it will restart the Pod and, potentially, place it onto another node:

$ kubectl delete po $POD_NAME

replace it if it's an individual Pod:

$ kubectl get po -n $namespace $POD_NAME -o yaml | kubectl replace -f -

JQuery - how to select dropdown item based on value


How do I reference a cell range from one worksheet to another using excel formulas?

Ok Got it, I downloaded a custom concatenation function and then just referenced its cells


    Function concat(useThis As Range, Optional delim As String) As String
 ' this function will concatenate a range of cells and return one string
 ' useful when you have a rather large range of cells that you need to add up
 Dim retVal, dlm As String
 retVal = ""
 If delim = Null Then
 dlm = ""
 dlm = delim
 End If
 For Each cell In useThis
 if cstr(cell.value)<>"" and cstr(cell.value)<>" " then
 retVal = retVal & cstr(cell.Value) & dlm
 end if
 If dlm <> "" Then
 retVal = Left(retVal, Len(retVal) - Len(dlm))
 End If
 concat = retVal
 End Function

What is the __del__ method, How to call it?

The __del__ method (note spelling!) is called when your object is finally destroyed. Technically speaking (in cPython) that is when there are no more references to your object, ie when it goes out of scope.

If you want to delete your object and thus call the __del__ method use

del obj1

which will delete the object (provided there weren't any other references to it).

I suggest you write a small class like this

class T:
    def __del__(self):
        print "deleted"

And investigate in the python interpreter, eg

>>> a = T()
>>> del a
>>> a = T()
>>> b = a
>>> del b
>>> del a
>>> def fn():
...     a = T()
...     print "exiting fn"
>>> fn()
exiting fn

Note that jython and ironpython have different rules as to exactly when the object is deleted and __del__ is called. It isn't considered good practice to use __del__ though because of this and the fact that the object and its environment may be in an unknown state when it is called. It isn't absolutely guaranteed __del__ will be called either - the interpreter can exit in various ways without deleteting all objects.

ListView with Add and Delete Buttons in each Row in android

You will first need to create a custom layout xml which will represent a single item in your list. You will add your two buttons to this layout along with any other items you want to display from your list.

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android=""
android:layout_height="match_parent" > 

    android:textStyle="bold" /> 

    android:text="Delete" /> 

    android:text="Add" />


Next you will need to create a Custom ArrayAdapter Class which you will use to inflate your xml layout, as well as handle your buttons and on click events.

public class MyCustomAdapter extends BaseAdapter implements ListAdapter { 
private ArrayList<String> list = new ArrayList<String>(); 
private Context context; 

public MyCustomAdapter(ArrayList<String> list, Context context) { 
    this.list = list; 
    this.context = context; 

public int getCount() { 
    return list.size(); 

public Object getItem(int pos) { 
    return list.get(pos); 

public long getItemId(int pos) { 
    return list.get(pos).getId();
    //just return 0 if your list items do not have an Id variable.

public View getView(final int position, View convertView, ViewGroup parent) {
    View view = convertView;
    if (view == null) {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
        view = inflater.inflate(R.layout.my_custom_list_layout, null);

    //Handle TextView and display string from your list
    TextView listItemText = (TextView)view.findViewById(; 

    //Handle buttons and add onClickListeners
    Button deleteBtn = (Button)view.findViewById(;
    Button addBtn = (Button)view.findViewById(;

    deleteBtn.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v) { 
            //do something
            list.remove(position); //or some other task
    addBtn.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v) { 
            //do something

    return view; 

Finally, in your activity you can instantiate your custom ArrayAdapter class and set it to your listview.

public class MyActivity extends Activity { 

protected void onCreate(Bundle savedInstanceState) { 

    //generate list
    ArrayList<String> list = new ArrayList<String>();

    //instantiate custom adapter
    MyCustomAdapter adapter = new MyCustomAdapter(list, this);

    //handle listview and assign adapter
    ListView lView = (ListView)findViewById(;

Hope this helps!

Adding two Java 8 streams, or an extra element to a stream

At the end of the day I'm not interested in combining streams, but in obtaining the combined result of processing each element of all those streams.

While combining streams might prove to be cumbersome (thus this thread), combining their processing results is fairly easy.

The key to solve is to create your own collector and ensure that the supplier function for the new collector returns the same collection every time (not a new one), the code below illustrates this approach.

package scratchpad;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class CombineStreams {
    public CombineStreams() {

    public static void main(String[] args) {
        List<String> resultList = new ArrayList<>();
        Collector<String, List<String>, List<String>> collector = Collector.of(
                () -> resultList,
                (list, item) -> {
                (llist, rlist) -> {
                    return llist;
        String searchString = "Wil";

        System.out.println("After processing first stream\n"
                + createFirstStream().filter(name -> name.contains(searchString)).collect(collector));

        System.out.println("After processing second stream\n"
                + createSecondStream().filter(name -> name.contains(searchString)).collect(collector));

        System.out.println("After processing third stream\n"
                + createThirdStream().filter(name -> name.contains(searchString)).collect(collector));


    private static Stream<String> createFirstStream() {
        return Arrays.asList(
                "William Shakespeare",
                "Emily Dickinson",
                "H. P. Lovecraft",
                "Arthur Conan Doyle",
                "Leo Tolstoy",
                "Edgar Allan Poe",
                "Robert Ervin Howard",
                "Rabindranath Tagore",
                "Rudyard Kipling",
                "John Donne",
                "Sarah Williams",
                "Oscar Wilde",
                "Alfred Tennyson",
                "William Blake",
                "Charles Dickens",
                "John Keats",
                "Theodor Herzl"

    private static Stream<String> createSecondStream() {
        return Arrays.asList(
                "Percy Bysshe Shelley",
                "Ernest Hemingway",
                "Barack Obama",
                "Anton Chekhov",
                "Henry Wadsworth Longfellow",
                "Arthur Schopenhauer",
                "Jacob De Haas",
                "George Gordon Byron",
                "Jack London",
                "Robert Frost",
                "Abraham Lincoln",
                "O. Henry",
                "Robert Louis Stevenson",
                "John Masefield",
                "James Joyce",
                "Clark Ashton Smith",
                "William Wordsworth",
                "Jane Austen"

    private static Stream<String> createThirdStream() {
        return Arrays.asList(
                "Niccolò Machiavelli",
                "Lewis Carroll",
                "Robert Burns",
                "Edgar Rice Burroughs",
                "John Milton",
                "Ralph Waldo Emerson",
                "Margaret Thatcher",
                "Sylvie d'Avigdor",
                "Marcus Tullius Cicero",
                "Banjo Paterson",
                "Woodrow Wilson",
                "Walt Whitman",
                "Theodore Roosevelt",
                "Agatha Christie",
                "Ambrose Bierce",
                "Nikola Tesla",
                "Franz Kafka"

"Error: Main method not found in class MyClass, please define the main method as..."

The problem is that you do not have a public void main(String[] args) method in the class you attempt to invoke.


  • must be static
  • must have exactly one String array argument (which may be named anything)
  • must be spelled m-a-i-n in lowercase.

Note, that you HAVE actually specified an existing class (otherwise the error would have been different), but that class lacks the main method.

use Lodash to sort array of object by value

This method orderBy does not change the input array, you have to assign the result to your array :

var chars = this.state.characters;

chars = _.orderBy(chars, ['name'],['asc']); // Use Lodash to sort array by 'name'

 this.setState({characters: chars})

How to obtain the start time and end time of a day?

Another one solution which does not depend on any framework is:

static public Date getStartOfADay(Date day) {
    final long oneDayInMillis = 24 * 60 * 60 * 1000;
    return new Date(day.getTime() / oneDayInMillis * oneDayInMillis);

static public Date getEndOfADay(Date day) {
    final long oneDayInMillis = 24 * 60 * 60 * 1000;
    return new Date((day.getTime() / oneDayInMillis + 1) * oneDayInMillis - 1);

Note that it returns UTC based time

Get the week start date and week end date from week number

This doesn't come from me, but it got the job done regardless:

SELECT DATEADD(wk, -1, DATEADD(DAY, 1-DATEPART(WEEKDAY, GETDATE()), DATEDIFF(dd, 0, GETDATE()))) --first day previous week
SELECT DATEADD(wk, 0, DATEADD(DAY, 1-DATEPART(WEEKDAY, GETDATE()), DATEDIFF(dd, 0, GETDATE()))) --first day current week

SELECT DATEADD(wk, 0, DATEADD(DAY, 0-DATEPART(WEEKDAY, GETDATE()), DATEDIFF(dd, 0, GETDATE()))) --last day previous week

I found it here.

Go to first line in a file in vim?

In command mode (press Esc if you are not sure) you can use:

  • gg,
  • :1,
  • 1G,
  • or 1gg.

How do I get Flask to run on port 80?

you can easily disable any process running on port 80 and then run this command

flask run --host --port 80

or if u prefer running it within the .py file

if __name__ == "__main__":, port=80)

Update a column value, replacing part of a string

Try this...

update [table_name] set [field_name] = 

How to check for changes on remote (origin) Git repository

I simply use

git fetch origin

to fetch the remote changes, and then I view both local and pending remote commits (and their associated changes) with the nice gitk tool involving the --all argument like:

gitk --all

How to specify multiple return types using type-hints

From the documentation

class typing.Union

Union type; Union[X, Y] means either X or Y.

Hence the proper way to represent more than one return data type is

from typing import Union

def foo(client_id: str) -> Union[list,bool]

But do note that typing is not enforced. Python continues to remain a dynamically-typed language. The annotation syntax has been developed to help during the development of the code prior to being released into production. As PEP 484 states, "no type checking happens at runtime."

>>> def foo(a:str) -> list:
...     return("Works")
>>> foo(1)

As you can see I am passing a int value and returning a str. However the __annotations__ will be set to the respective values.

>>> foo.__annotations__ 
{'return': <class 'list'>, 'a': <class 'str'>}

Please Go through PEP 483 for more about Type hints. Also see What are Type hints in Python 3.5?

Kindly note that this is available only for Python 3.5 and upwards. This is mentioned clearly in PEP 484.

How to change Maven local repository in eclipse

location can be specified in Maven->Installation -> Global Settings: settings.xml

enter image description here

How do I POST form data with UTF-8 encoding by using curl?

You CAN use UTF-8 in the POST request, all you need is to specify the charset in your request.

You should use this request:

curl -X POST -H "Content-Type: application/x-www-form-urlencoded; charset=utf-8" --data-ascii "content=derinhält&date=asdf"

Is embedding background image data into CSS as Base64 good or bad practice?

Bringing a bit for users of Sublime Text 2, there is a plugin that gives the base64 code we load the images in the ST.

Called Image2base64:

PS: Never save this file generated by the plugin because it would overwrite the file and would destroy.

Printing Lists as Tabular Data

>>> import pandas
>>> pandas.DataFrame(data, teams_list, teams_list)
           Man Utd  Man City  T Hotspur
Man Utd    1        2         1        
Man City   0        1         0        
T Hotspur  2        4         2        

Child with max-height: 100% overflows parent

Here is a solution for a recently opened question marked as a duplicate of this question. The <img> tag was exceeding the max-height of the parent <div>.

Broken: Fiddle

Working: Fiddle

In this case, adding display:flex to the 2 parent <div> tags was the answer

php static function

Entire difference is, you don't get $this supplied inside the static function. If you try to use $this, you'll get a Fatal error: Using $this when not in object context.

Well, okay, one other difference: an E_STRICT warning is generated by your first example.

How to test web service using command line curl

From the documentation on :

HTTP Authentication

curl --user name:password 

Put a file to a HTTP server with curl:

curl --upload-file uploadfile

Send post data with curl:

curl --data "birthyear=1905&press=%20OK%20"

What is the difference between old style and new style classes in Python?

Old style classes are still marginally faster for attribute lookup. This is not usually important, but it may be useful in performance-sensitive Python 2.x code:

In [3]: class A:
   ...:     def __init__(self):
   ...:         self.a = 'hi there'

In [4]: class B(object):
   ...:     def __init__(self):
   ...:         self.a = 'hi there'

In [6]: aobj = A()
In [7]: bobj = B()

In [8]: %timeit aobj.a
10000000 loops, best of 3: 78.7 ns per loop

In [10]: %timeit bobj.a
10000000 loops, best of 3: 86.9 ns per loop

How to capture a list of specific type with mockito

List<String> mockedList = mock(List.class);

List<String> l = new ArrayList();


ArgumentCaptor<List> argumentCaptor = ArgumentCaptor.forClass(List.class);


List<String> capturedArgument = argumentCaptor.<List<String>>getValue();

assertThat(capturedArgument, hasItem("someElement"));

How do I escape a percentage sign in T-SQL?

You can use the code below to find a specific value.

WHERE col1 LIKE '%[%]75%'

When you want a single digit number after the% sign, you can write the following code.

WHERE col2 LIKE '%[%]_'

Java random number with given length

try this:

public int getRandomNumber(int min, int max) {
    return (int) Math.floor(Math.random() * (max - min + 1)) + min;

casting Object array to Integer array error

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.Integer;

you try to cast an Array of Object to cast into Array of Integer. You cant do it. This type of downcast is not permitted.

You can make an array of Integer, and after that copy every value of the first array into second array.

How to create a dotted <hr/> tag?

The <hr> tag is just a short element with a border:

<hr style="border-style: dotted;" />

Ruby max integer

There is no maximum since Ruby 2.4, as Bignum and Fixnum got unified into Integer. see Feature #12005

> (2 << 1000).is_a? Fixnum
(irb):322: warning: constant ::Fixnum is deprecated
=> true

> 1.is_a? Bignum
(irb):314: warning: constant ::Bignum is deprecated
=> true

> (2 << 1000).class
=> Integer

There won't be any overflow, what would happen is an out of memory.

JavaScript alert not working in Android WebView

As others indicated, setting the WebChromeClient is needed to get alert() to work. It's sufficient to just set the default WebChromeClient():

mWebView.setWebChromeClient(new WebChromeClient());

Thanks for all the comments below. Including John Smith's who indicated that you needed to enable JavaScript.

Maven 3 warnings about build.plugins.plugin.version

Add a <version> element after the <plugin> <artifactId> in your pom.xml file. Find the following text:


Add the version tag to it:


The warning should be resolved.

Regarding this:

'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing

Many people have mentioned why the issue is happening, but fail to suggest a fix. All I needed to do was to go into my POM file for my project, and add the <version> tag as shown above.

To discover the version number, one way is to look in Maven's output after it finishes running. Where you are missing version numbers, Maven will display its default version:

[INFO] --- maven-compiler-plugin:2.3.2:compile (default-compile) @ entities ---

Take that version number (as in the 2.3.2 above) and add it to your POM, as shown.

Change WPF controls from a non-main thread using Dispatcher.Invoke

When a thread is executing and you want to execute the main UI thread which is blocked by current thread, then use the below:

current thread:

    new object[] { parameter1, parameter2 }); // if passing 2 parameters to method.

Main UI thread:

    DispatcherPriority.Background, new Action(() => MethodName(parameter)));

Strip off URL parameter with PHP

parse_str($queryString, $vars);
$queryString = http_build_query($vars);

parse_str parses a query string, http_build_query creates a query string.

How to install plugins to Sublime Text 2 editor?

You need to install Package Control first (from the Python console in Sublime. Visit for more info), and then install emmet from their repository.

<strong> vs. font-weight:bold & <em> vs. font-style:italic

<strong> and <em> - unlike <b> and <i> - have clear purpose for web browsers for the blind.

A blind person doesn't browse the web visually, but by sound such as text readers. <strong> and <em>, in addition to encouraging something to be bold or italic, also convey loudness or stressing syllables respectively (OH MY! & Ooooooh Myyyyyyy!). Audio-only browsers are unpredictable when it comes to <b> and <i>... they may make them loud or stress them or they may not... you never can be sure unless you use <strong> and <em>.

Select elements by attribute in CSS

It's also possible to select attributes regardless of their content, in modern browsers


[data-my-attribute] {
   /* Styles */

[anything] {
   /* Styles */

For example:

Works on a very significant percentage of browsers.

Note this can also be used in a JQuery selector, or using document.querySelector

Controlling execution order of unit tests in Visual Studio

You can Use Playlist

Right click on the test method -> Add to playlist -> New playlist

the execution order will be as you add them to the playlist but if you want to change it you have the file

enter image description here

jquery clone div and append it after specific div

This works great if a straight copy is in order. If the situation calls for creating new objects from templates, I usually wrap the template div in a hidden storage div and use jquery's html() in conjunction with clone() applying the following technique:

#element-storage {
    display: none;
    top: 0;
    right: 0;
    position: fixed;
    width: 0;
    height: 0;

$("#new-div").append($("#template").clone().html(function(index, oldHTML){ 
    // .. code to modify template, e.g. below:
    var newHTML = "";
    newHTML = oldHTML.replace("[firstname]", "Tom");
    newHTML = newHTML.replace("[lastname]", "Smith");
    // newHTML = newHTML.replace(/[Example Replace String]/g, "Replacement"); // regex for global replace
    return newHTML;

<div id="element-storage">
  <div id="template">
    <p>Hello [firstname] [lastname]</p>

<div id="new-div">


How to convert milliseconds to "hh:mm:ss" format?

The answer marked as correct has a little mistake,

String myTime = String.format("%02d:%02d:%02d",
            TimeUnit.MILLISECONDS.toMinutes(millis) -
                    TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millis)), // The change is in this line
            TimeUnit.MILLISECONDS.toSeconds(millis) -

for example this is an example of the value that i get:


This is the solution to get the right format is:

String myTime =  String.format("%02d:%02d:%02d",
                TimeUnit.MILLISECONDS.toHours(millis) -
                TimeUnit.MILLISECONDS.toMinutes(millis) -
                TimeUnit.MILLISECONDS.toSeconds(millis) -

getting as a result a correct format:


other option to get the format hh:mm:ss is just :

   Date myDate = new Date(timeinMillis);
   SimpleDateFormat formatter = new SimpleDateFormat("HH:mm:ss");
   String myTime = formatter.format(myDate);

How do I POST with multipart form data using fetch?

I was recently working with IPFS and worked this out. A curl example for IPFS to upload a file looks like this:

curl -i -H "Content-Type: multipart/form-data; boundary=CUSTOM" -d $'--CUSTOM\r\nContent-Type: multipart/octet-stream\r\nContent-Disposition: file; filename="test"\r\n\r\nHello World!\n--CUSTOM--' "http://localhost:5001/api/v0/add"

The basic idea is that each part (split by string in boundary with --) has it's own headers (Content-Type in the second part, for example.) The FormData object manages all this for you, so it's a better way to accomplish our goals.

This translates to fetch API like this:

const formData = new FormData()
formData.append('blob', new Blob(['Hello World!\n']), 'test')

fetch('http://localhost:5001/api/v0/add', {
  method: 'POST',
  body: formData
.then(r => r.json())
.then(data => {

Name [jdbc/mydb] is not bound in this Context

For those who use Tomcat with Bitronix, this will fix the problem:

The error indicates that no handler could be found for your datasource 'jdbc/mydb', so you'll need to make sure your tomcat server refers to your bitronix configuration files as needed.

In case you're using and files to configure the datasource, specify these two JVM arguments in tomcat:

(if you already used them, make sure your references are correct):

  • btm.root


-Dbtm.root="C:\Program Files\Apache Software Foundation\Tomcat 7.0.59""C:\Program Files\Apache Software Foundation\Tomcat 7.0.59\conf\" 

Now, restart your server and check the log.

How to make <input type="date"> supported on all browsers? Any alternatives?

This is bit of an opinion piece, but we had great success with WebShims. It can decay cleanly to use jQuery datepicker if native is not available. Demo here

Ansible: create a user with sudo privileges

Sometimes it's knowing what to ask. I didn't know as I am a developer who has taken on some DevOps work.

Apparently 'passwordless' or NOPASSWD login is a thing which you need to put in the /etc/sudoers file.

The answer to my question is at Ansible: best practice for maintaining list of sudoers.

The Ansible playbook code fragment looks like this from my problem:

- name: Make sure we have a 'wheel' group
    name: wheel
    state: present

- name: Allow 'wheel' group to have passwordless sudo
    dest: /etc/sudoers
    state: present
    regexp: '^%wheel'
    line: '%wheel ALL=(ALL) NOPASSWD: ALL'
    validate: 'visudo -cf %s'

- name: Add sudoers users to wheel group

- name: Set up authorized keys for the deployer user
  authorized_key: user=deployer key="{{item}}"
    - /home/railsdev/.ssh/

And the best part is that the solution is idempotent. It doesn't add the line


to /etc/sudoers when the playbook is run a subsequent time. And yes...I was able to ssh into the server as "deployer" and run sudo commands without having to give a password.

How do I compare two hashes?

Rails is deprecating the diff method.

For a quick one-liner:

hash1.to_s == hash2.to_s

SQL Server - stop or break execution of a SQL script

Thx for the answer!

raiserror() works fine but you shouldn't forget the return statement otherwise the script continues without error! (hense the raiserror isn't a "throwerror" ;-)) and of course doing a rollback if necessary!

raiserror() is nice to tell the person who executes the script that something went wrong.

How can I convert an image into a Base64 string?

If you need Base64 over JSON, check out Jackson: it has explicit support for binary data read/write as Base64 at both the low level (JsonParser, JsonGenerator) and data-binding level. So you can just have POJOs with byte[] properties, and encoding/decoding is automatically handled.

And pretty efficiently too, should that matter.

Static vs class functions/variables in Swift classes?

There's one more difference. class can be used to define type properties of computed type only. If you need a stored type property use static instead.

Class :- reference type

struct :- value type

How can I determine whether a 2D Point is within a Polygon?

Here is golang version of @nirg answer (inspired by C# code by @@m-katz)

func isPointInPolygon(polygon []point, testp point) bool {
    minX := polygon[0].X
    maxX := polygon[0].X
    minY := polygon[0].Y
    maxY := polygon[0].Y

    for _, p := range polygon {
        minX = min(p.X, minX)
        maxX = max(p.X, maxX)
        minY = min(p.Y, minY)
        maxY = max(p.Y, maxY)

    if testp.X < minX || testp.X > maxX || testp.Y < minY || testp.Y > maxY {
        return false

    inside := false
    j := len(polygon) - 1
    for i := 0; i < len(polygon); i++ {
        if (polygon[i].Y > testp.Y) != (polygon[j].Y > testp.Y) && testp.X < (polygon[j].X-polygon[i].X)*(testp.Y-polygon[i].Y)/(polygon[j].Y-polygon[i].Y)+polygon[i].X {
            inside = !inside
        j = i

    return inside

Space between two rows in a table?

tr { 
    display: block;
    margin-bottom: 5px;

How to get DropDownList SelectedValue in Controller in MVC

If you're looking for something lightweight, I'd append a parameter to your action.

public ActionResult ShowAllMobileDetails(MobileViewModel MV, string ddlVendor)
    string strDDLValue = ddlVendor; // Of course, this becomes silly.

    return View(MV);

What's happening in your code now, is you're passing the first string argument of "ddlVendor" to Html.DropDownList, and that's telling the MVC framework to create a <select> element with a name of "ddlVendor." When the user submits the form client-side, then, it will contain a value to that key.

When MVC tries to parse that request into MV, it's going to look for MobileList and Vendor and not find either, so it's not going to be populated. By adding this parameter, or using FormCollection as another answer has suggested, you're asking MVC to specifically look for a form element with that name, so it should then populate the parameter value with the posted value.

Write lines of text to a file in R

tidyverse edition with pipe and write_lines() from readr

c('Hello', 'World') %>% write_lines( "output.txt")

How to determine previous page URL in Angular?


Actually since Angular 7.2 there is not need to use a service for saving the previous url. You could just use the state object to set the last url before linking to the login page. Here is an example for a login scenario.

@Component({ ... })
class SomePageComponent {
  constructor(private router: Router) {}

  checkLogin() {
    if (!this.auth.loggedIn()) {
      this.router.navigate(['login'], { state: { redirect: this.router.url } });
class LoginComponent {
  constructor(private router: Router) {}

  backToPreviousPage() {
    const { redirect } = window.history.state;

    this.router.navigateByUrl(redirect || '/homepage');

Additionally you could also pass the data in the template:

  template: '<a routerLink="/some-route" [state]="{ redirect: router.url}">Go to some route</a>'
class SomePageComponent {
  constructor(public router: Router) {}

fe_sendauth: no password supplied

This occurs if the password for the database is not given.

default="postgres://postgres:[email protected]:5432/DBname"

How to create a multi line body in C# System.Net.Mail.MailMessage

The key to this is when you said

using Outlook.

I have had the same problem with perfectly formatted text body e-mails. It's Outlook that make trash out of it. Occasionally it is kind enough to tell you that "extra line breaks were removed". Usually it just does what it wants and makes you look stupid.

So I put in a terse body and put my nice formatted text in an attachement. You can either do that or format the body in HTML.

how to make a countdown timer in java

You'll see people using the Timer class to do this. Unfortunately, it isn't always accurate. Your best bet is to get the system time when the user enters input, calculate a target system time, and check if the system time has exceeded the target system time. If it has, then break out of the loop.

spark submit add multiple jars in classpath

For --driver-class-path option you can use : as delimeter to pass multiple jars. Below is the example with spark-shell command but I guess the same should work with spark-submit as well

    spark-shell --driver-class-path /path/to/example.jar:/path/to/another.jar

Spark version: 2.2.0

How to send a “multipart/form-data” POST in Android with Volley

I might be wrong on this but I think you need to implement your own for this because the default ones (HurlStack if version > Gingerbread or HttpClientStack) don't deal with multipart/form-data.


And indeed I was wrong. I was able to do it using MultipartEntity in Request like this:

public class MultipartRequest extends Request<String> {

    private MultipartEntity entity = new MultipartEntity();

    private static final String FILE_PART_NAME = "file";
    private static final String STRING_PART_NAME = "text";

    private final Response.Listener<String> mListener;
    private final File mFilePart;
    private final String mStringPart;

    public MultipartRequest(String url, Response.ErrorListener errorListener, Response.Listener<String> listener, File file, String stringPart)
        super(Method.POST, url, errorListener);

        mListener = listener;
        mFilePart = file;
        mStringPart = stringPart;

    private void buildMultipartEntity()
        entity.addPart(FILE_PART_NAME, new FileBody(mFilePart));
            entity.addPart(STRING_PART_NAME, new StringBody(mStringPart));
        catch (UnsupportedEncodingException e)

    public String getBodyContentType()
        return entity.getContentType().getValue();

    public byte[] getBody() throws AuthFailureError
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        catch (IOException e)
            VolleyLog.e("IOException writing to ByteArrayOutputStream");
        return bos.toByteArray();

    protected Response<String> parseNetworkResponse(NetworkResponse response)
        return Response.success("Uploaded", getCacheEntry());

    protected void deliverResponse(String response)

It's pretty raw but I tried it with an image and a simple string and it works. The response is a placeholder, doesn't make much sense to return a Response String in this case. I had problems using apache httpmime to use MultipartEntity so I used this don't know if there's a better way. Hope it helps.


You can use httpmime without using httpclientandroidlib, the only dependency is httpcore.

How to set a default value for an existing column

The correct way to do this is as follows:

  1. Run the command:

    sp_help [table name] 
  2. Copy the name of the CONSTRAINT.


  4. Run the command below:


jQuery looping .each() JSON key/value not working

Since you have an object, not a jQuery wrapper, you need to use a different variant of $.each()

$.each(json, function (key, data) {
    $.each(data, function (index, data) {
        console.log('index', data)

Demo: Fiddle

How to upload, display and save images using node.js and express

First of all, you should make an HTML form containing a file input element. You also need to set the form's enctype attribute to multipart/form-data:

<form method="post" enctype="multipart/form-data" action="/upload">
    <input type="file" name="file">
    <input type="submit" value="Submit">

Assuming the form is defined in index.html stored in a directory named public relative to where your script is located, you can serve it this way:

const http = require("http");
const path = require("path");
const fs = require("fs");

const express = require("express");

const app = express();
const httpServer = http.createServer(app);

const PORT = process.env.PORT || 3000;

httpServer.listen(PORT, () => {
  console.log(`Server is listening on port ${PORT}`);

// put the HTML file containing your form in a directory named "public" (relative to where this script is located)
app.get("/", express.static(path.join(__dirname, "./public")));

Once that's done, users will be able to upload files to your server via that form. But to reassemble the uploaded file in your application, you'll need to parse the request body (as multipart form data).

In Express 3.x you could use express.bodyParser middleware to handle multipart forms but as of Express 4.x, there's no body parser bundled with the framework. Luckily, you can choose from one of the many available multipart/form-data parsers out there. Here, I'll be using multer:

You need to define a route to handle form posts:

const multer = require("multer");

const handleError = (err, res) => {
    .end("Oops! Something went wrong!");

const upload = multer({
  dest: "/path/to/temporary/directory/to/store/uploaded/files"
  // you might also want to set some limits:
  upload.single("file" /* name attribute of <file> element in your form */),
  (req, res) => {
    const tempPath = req.file.path;
    const targetPath = path.join(__dirname, "./uploads/image.png");

    if (path.extname(req.file.originalname).toLowerCase() === ".png") {
      fs.rename(tempPath, targetPath, err => {
        if (err) return handleError(err, res);

          .end("File uploaded!");
    } else {
      fs.unlink(tempPath, err => {
        if (err) return handleError(err, res);

          .end("Only .png files are allowed!");

In the example above, .png files posted to /upload will be saved to uploaded directory relative to where the script is located.

In order to show the uploaded image, assuming you already have an HTML page containing an img element:

<img src="/image.png" />

you can define another route in your express app and use res.sendFile to serve the stored image:

app.get("/image.png", (req, res) => {
  res.sendFile(path.join(__dirname, "./uploads/image.png"));

How to solve "Connection reset by peer: socket write error"?

I had the same problem with small difference:

Exception was raised at the moment of flushing

It is a different stackoverflow issue. The brief explanation was a wrong response header setting:

response.setHeader("Content-Encoding", "gzip");

despite uncompressed response data content.

So the the connection was closed by the browser.

sql ORDER BY multiple values in specific order?

you can use position(text in text) in order by for ordering the sequence

Calling C/C++ from Python?

I started my journey in the Python <-> C++ binding from this page, with the objective of linking high level data types (multidimensional STL vectors with Python lists) :-)

Having tried the solutions based on both ctypes and boost.python (and not being a software engineer) I have found them complex when high level datatypes binding is required, while I have found SWIG much more simple for such cases.

This example uses therefore SWIG, and it has been tested in Linux (but SWIG is available and is widely used in Windows too).

The objective is to make a C++ function available to Python that takes a matrix in form of a 2D STL vector and returns an average of each row (as a 1D STL vector).

The code in C++ ("code.cpp") is as follow:

#include <vector>
#include "code.h"

using namespace std;

vector<double> average (vector< vector<double> > i_matrix) {

  // Compute average of each row..
  vector <double> averages;
  for (int r = 0; r < i_matrix.size(); r++){
    double rsum = 0.0;
    double ncols= i_matrix[r].size();
    for (int c = 0; c< i_matrix[r].size(); c++){
      rsum += i_matrix[r][c];
  return averages;

The equivalent header ("code.h") is:

#ifndef _code
#define _code

#include <vector>

std::vector<double> average (std::vector< std::vector<double> > i_matrix);


We first compile the C++ code to create an object file:

g++ -c -fPIC code.cpp

We then define a SWIG interface definition file ("code.i") for our C++ functions.

%module code
#include "code.h"
%include "std_vector.i"
namespace std {

  /* On a side note, the names VecDouble and VecVecdouble can be changed, but the order of first the inner vector matters! */
  %template(VecDouble) vector<double>;
  %template(VecVecdouble) vector< vector<double> >;

%include "code.h"

Using SWIG, we generate a C++ interface source code from the SWIG interface definition file..

swig -c++ -python code.i

We finally compile the generated C++ interface source file and link everything together to generate a shared library that is directly importable by Python (the "_" matters):

g++ -c -fPIC code_wrap.cxx  -I/usr/include/python2.7 -I/usr/lib/python2.7
g++ -shared -Wl,-soname, -o code.o code_wrap.o

We can now use the function in Python scripts:

#!/usr/bin/env python

import code
a= [[3,5,7],[8,10,12]]
print a
b = code.average(a)
print "Assignment done"
print a
print b

How do I change the background color of the ActionBar of an ActionBarActivity using XML?

I had the same problem, where my Action Bar would turn grey when I entered that code. Chances are your original style sheet looked like this:

<style name="AppBaseTheme" parent="android:Theme.Holo.Light.DarkActionBar">
    <!-- API 14 theme customizations can go here. -->

The "DarkActionBar" was what was keeping your Action Bar grey. I changed it to this, and it worked:

<style name="AppBaseTheme" parent="android:Theme.Holo.Light">
    <!-- API 14 theme customizations can go here. -->
    <item name="android:actionBarStyle">@style/MyActionBar</item>

<style name="MyActionBar" parent="@android:style/Widget.Holo.Light.ActionBar">
    <item name="android:background">#2aa4cd</item>
    <item name="android:titleTextStyle">@style/Theme.MyAppTheme.ActionBar.TitleTextStyle</item>

<style name="Theme.MyAppTheme.ActionBar.TitleTextStyle" parent="android:style/TextAppearance.Holo.Widget.ActionBar.Title">
    <item name="android:textColor">#FFFFFF</item>

I also threw in how to edit the text color. Also, no need to change anything surrounding the resources.


When to use React "componentDidUpdate" method?

I have used componentDidUpdate() in highchart.

Here is a simple example of this component.

import React, { PropTypes, Component } from 'react';
window.Highcharts = require('highcharts');

export default class Chartline extends React.Component {
  constructor(props) {
    this.state = {
      chart: ''

  public componentDidUpdate() {
    // console.log(this.props.candidate, 'this.props.candidate')
    if (this.props.category) {
      const category = this.props.category ? this.props.category : {};
      console.log('category', category);
      window.Highcharts.chart('jobcontainer_' + category._id, {
        title: {
          text: ''
        plotOptions: {
          series: {
            cursor: 'pointer'
        chart: {
          defaultSeriesType: 'spline'
        xAxis: {
          // categories: candidate.dateArr,
          categories: ['Day1', 'Day2', 'Day3', 'Day4', 'Day5', 'Day6', 'Day7'],
          showEmpty: true
        labels: {
          style: {
            color: 'white',
            fontSize: '25px',
            fontFamily: 'SF UI Text'
        series: [
            name: 'Low',
            color: '#9B260A',
            data: category.lowcount
            name: 'High',
            color: '#0E5AAB',
            data: category.highcount
            name: 'Average',
            color: '#12B499',
            data: category.averagecount
  public render() {
    const category = this.props.category ? this.props.category : {};
    console.log('render category', category);
    return <div id={'jobcontainer_' + category._id} style={{ maxWidth: '400px', height: '180px' }} />;

How to analyze information from a Java core dump?

If you are using an IBM JVM, download the IBM Thread and Monitor Dump Analyzer. It is an excellent tool. It provides thread detail and can point out deadlocks, etc. The following blog post provides a nice overview on how to use it.

How to write LDAP query to test if user is member of a group?

I would add one more thing to Marc's answer: The memberOf attribute can't contain wildcards, so you can't say something like "memberof=CN=SPS*", and expect it to find all groups that start with "SPS".

SQL Server Text type vs. varchar data type

If you're using SQL Server 2005 or later, use varchar(MAX). The text datatype is deprecated and should not be used for new development work. From the docs:


ntext , text, and image data types will be removed in a future version of Microsoft SQL Server. Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar(max), varchar(max), and varbinary(max) instead.

Cookie blocked/not saved in IFRAME in Internet Explorer

This post provides some commentary on P3P and a short-cut solution that reduces the problems with IE7 and IE8.

How do you tell if caps lock is on using JavaScript?

Based on answer of @joshuahedlund since it worked fine for me.

I made the code a function so it can be reused, and linked it to the body in my case. It can be linked to the password field only if you prefer.

<script language="javascript" type="text/javascript" >
function checkCapsLock(e, divId) { 
        e = e;
    } else {
        e = window.event;
    var s = String.fromCharCode( e.which );
    if ((s.toUpperCase() === s && s.toLowerCase() !== s && !e.shiftKey)|| //caps is on
      (s.toUpperCase() !== s && s.toLowerCase() === s && e.shiftKey)) {
    } else if ((s.toLowerCase() === s && s.toUpperCase() !== s && !e.shiftKey)||
      (s.toLowerCase() !== s && s.toUpperCase() === s && e.shiftKey)) { //caps is off
   } //else upper and lower are both same (i.e. not alpha key - so do not hide message if already on but do not turn on if alpha keys not hit yet)
.errorDiv {
    display: none;
    font-size: 12px;
    color: red;
    word-wrap: break-word;
    text-overflow: clip;
    max-width: 200px;
    font-weight: normal;
<body  onkeypress="checkCapsLock(event, 'CapsWarn');" >
<input name="password" id="password" type="password" autocomplete="off">
<div id="CapsWarn" class="errorDiv">Capslock is ON !</div>

How can I increase the size of a bootstrap button?

Use block level buttons, those that span the full width of a parent You can achieve this by adding btn-block class your button element.

Documentation here

Vertically align text within input field of fixed-height without display: table or padding?

You should remove your title text and use the input placeholder for your label's title. Some visual and CSS work after that and your form will be looking tight and user friendly. I'm aware of the disadvantages but this will completely relieve the alignment wrestling.

Bash: Syntax error: redirection unexpected

On my machine, if I run a script directly, the default is bash.

If I run it with sudo, the default is sh.

That’s why I was hitting this problem when I used sudo.

Pass Javascript Variable to PHP POST

Yes you could use an <input type="hidden" /> and set the value of that hidden field in your javascript code so it gets posted with your other form data.

iterating over and removing from a map

Here is a code sample to use the iterator in a for loop to remove the entry.

Map<String, String> map = new HashMap<String, String>() {
    put("test", "test123");
    put("test2", "test456");

for(Iterator<Map.Entry<String, String>> it = map.entrySet().iterator(); it.hasNext(); ) {
    Map.Entry<String, String> entry =;
    if(entry.getKey().equals("test")) {

system("pause"); - Why is it wrong?

In summary, it has to pause the programs execution and make a system call and allocate unnecessary resources when you could be using something as simple as cin.get(). People use System("PAUSE") because they want the program to wait until they hit enter to they can see their output. If you want a program to wait for input, there are built in functions for that which are also cross platform and less demanding.

Further explanation in this article.

Fastest check if row exists in PostgreSQL

select true from tablename where condition limit 1;

I believe that this is the query that postgres uses for checking foreign keys.

In your case, you could do this in one go too:

insert into yourtable select $userid, $rightid, $count where not (select true from yourtable where userid = $userid limit 1);

How is VIP swapping + CNAMEs better than IP swapping + A records?

A VIP swap is an internal change to Azure's routers/load balancers, not an external DNS change. They're just routing traffic to go from one internal [set of] server[s] to another instead. Therefore the DNS info for doesn't change at all. Therefore the change for people accessing via the IP bound to (and CNAME'd by you) will see the change as soon as the VIP swap is complete.

How to execute shell command in Javascript

If you are using npm you can use the shelljs package

To install: npm install [-g] shelljs

var shell = require('shelljs');'*.js').forEach(function (file) {
// do something

See more:

How to increment a JavaScript variable using a button press event


<script type="text/javascript">
var counter = 0;


<button onclick="counter++">Increment</button>

What is the easiest way to get current GMT time in Unix timestamp format?

Or just simply using the datetime standard module

In [2]: from datetime import timezone, datetime
   ...: int( * 1000)
Out[2]: 1514901741720

You can truncate or multiply depending on the resolution you want. This example is outputting millis.

If you want a proper Unix timestamp (in seconds) remove the * 1000

phpMyAdmin allow remote users

The other answers so far seem to advocate the complete replacement of the <Directory/> block, this is not needed and may remove extra settings like the 'AddDefaultCharset UTF-8' now included.

To allow remote access you need to add 1 line to the 2.4 config block or change 2 lines in the 2.2 (depending on your apache version):

<Directory /usr/share/phpMyAdmin/>
   AddDefaultCharset UTF-8

   <IfModule mod_authz_core.c>
     # Apache 2.4
       #ADD following line:
       Require all granted
       Require ip
       Require ip ::1
   <IfModule !mod_authz_core.c>
     # Apache 2.2
     #CHANGE following 2 lines:
     Order Allow,Deny
     Allow from All
     Allow from
     Allow from ::1

How do I prevent and/or handle a StackOverflowException?

I had a stackoverflow today and i read some of your posts and decided to help out the Garbage Collecter.

I used to have a near infinite loop like this:

    class Foo
        public Foo()

        public void Go()
            for (float i = float.MinValue; i < float.MaxValue; i+= 0.000000000000001f)
                byte[] b = new byte[1]; // Causes stackoverflow

Instead let the resource run out of scope like this:

class Foo
    public Foo()

    public void GoHelper()
        for (float i = float.MinValue; i < float.MaxValue; i+= 0.000000000000001f)

    public void Go()
        byte[] b = new byte[1]; // Will get cleaned by GC
    }   // right now

It worked for me, hope it helps someone.

List all virtualenv

If you are using virtualenv or Python 3's built in venv the above answers might not work.

If you are on Linux, just locate the activate script that is always present inside a env.

locate -b '\activate' | grep "/home"

This will grab all Python virtual environments present inside your home directory.

See Demo Here

Iterate through string array in Java

I would argue instead of testing i less than elements.length - 1 testing i + 1 less than elements.length. You aren't changing the domain of the array that you are looking at (i.e. ignoring the last element), but rather changing the greatest element you are looking at in each iteration.

String[] elements = { "a", "a","a","a" };

for(int i = 0; i + 1 < elements.length; i++) {
    String first = elements[i];
    String second = elements[i+1];
    //do something with the two strings

Python dictionary: Get list of values for list of keys

Pandas does this very elegantly, though ofc list comprehensions will always be more technically Pythonic. I don't have time to put in a speed comparison right now (I'll come back later and put it in):

import pandas as pd
mydict = {'one': 1, 'two': 2, 'three': 3}
mykeys = ['three', 'one']
temp_df = pd.DataFrame().append(mydict)
# You can export DataFrames to a number of formats, using a list here. 
# Returns: array([ 3.,  1.])

# If you want a dict then use this instead:
# temp_df[mykeys].to_dict(orient='records')[0]
# Returns: {'one': 1.0, 'three': 3.0}

JVM option -Xss - What does it do exactly?

If I am not mistaken, this is what tells the JVM how much successive calls it will accept before issuing a StackOverflowError. Not something you wish to change generally.

Smooth scroll without the use of jQuery

I recently set out to solve this problem in a situation where jQuery wasn't an option, so I'm logging my solution here just for posterity.

var scroll = (function() {

    var elementPosition = function(a) {
        return function() {
            return a.getBoundingClientRect().top;

    var scrolling = function( elementID ) {

        var el = document.getElementById( elementID ),
            elPos = elementPosition( el ),
            duration = 400,
            increment = Math.round( Math.abs( elPos() )/40 ),
            time = Math.round( duration/increment ),
            prev = 0,

        function scroller() {
            E = elPos();

            if (E === prev) {
            } else {
                prev = E;

            increment = (E > -20 && E < 20) ? ((E > - 5 && E < 5) ? 1 : 5) : increment;

            if (E > 1 || E < -1) {

                if (E < 0) {
                    window.scrollBy( 0,-increment );
                } else {
                    window.scrollBy( 0,increment );

                setTimeout(scroller, time);

            } else {

                el.scrollTo( 0,0 );



    return {
        To: scrolling


/* usage */

The scroll() function uses the Revealing Module Pattern to pass the target element's id to its scrolling() function, via scroll.To('id'), which sets the values used by the scroller() function.


In scrolling():

  • el : the target DOM object
  • elPos : returns a function via elememtPosition() which gives the position of the target element relative to the top of the page each time it's called.
  • duration : transition time in milliseconds.
  • increment : divides the starting position of the target element into 40 steps.
  • time : sets the timing of each step.
  • prev : the target element's previous position in scroller().
  • E : holds the target element's position in scroller().

The actual work is done by the scroller() function which continues to call itself (via setTimeout()) until the target element is at the top of the page or the page can scroll no more.

Each time scroller() is called it checks the current position of the target element (held in variable E) and if that is > 1 OR < -1 and if the page is still scrollable shifts the window by increment pixels - up or down depending if E is a positive or negative value. When E is neither > 1 OR < -1, or E === prev the function stops. I added the DOMElement.scrollTo() method on completion just to make sure the target element was bang on the top of the window (not that you'd notice it being out by a fraction of a pixel!).

The if statement on line 2 of scroller() checks to see if the page is scrolling (in cases where the target might be towards the bottom of the page and the page can scroll no further) by checking E against its previous position (prev).

The ternary condition below it reduce the increment value as E approaches zero. This stops the page overshooting one way and then bouncing back to overshoot the other, and then bouncing back to overshoot the other again, ping-pong style, to infinity and beyond.

If your page is more that c.4000px high you might want to increase the values in the ternary expression's first condition (here at +/-20) and/or the divisor which sets the increment value (here at 40).

Playing about with duration, the divisor which sets increment, and the values in the ternary condition of scroller() should allow you to tailor the function to suit your page.

  • JSFiddle

  • N.B.Tested in up-to-date versions of Firefox and Chrome on Lubuntu, and Firefox, Chrome and IE on Windows8.

How to use onClick() or onSelect() on option tag in a JSP page?

in this example de select tag is named as: aula_clase_cb

<select class="form-control" id="aula_clase_cb" >

document.getElementById("aula_clase_cb").onchange = function(e){
    id = document.getElementById('aula_clase_cb').value;
    alert("id: "+id);

What is a "thread" (really)?

A thread is an execution context, which is all the information a CPU needs to execute a stream of instructions.

Suppose you're reading a book, and you want to take a break right now, but you want to be able to come back and resume reading from the exact point where you stopped. One way to achieve that is by jotting down the page number, line number, and word number. So your execution context for reading a book is these 3 numbers.

If you have a roommate, and she's using the same technique, she can take the book while you're not using it, and resume reading from where she stopped. Then you can take it back, and resume it from where you were.

Threads work in the same way. A CPU is giving you the illusion that it's doing multiple computations at the same time. It does that by spending a bit of time on each computation. It can do that because it has an execution context for each computation. Just like you can share a book with your friend, many tasks can share a CPU.

On a more technical level, an execution context (therefore a thread) consists of the values of the CPU's registers.

Last: threads are different from processes. A thread is a context of execution, while a process is a bunch of resources associated with a computation. A process can have one or many threads.

Clarification: the resources associated with a process include memory pages (all the threads in a process have the same view of the memory), file descriptors (e.g., open sockets), and security credentials (e.g., the ID of the user who started the process).

How to make a gui in python

For a start I would recommend wxglade. It is a rather easy to use tool that helps you build wxPython applications. wx is already cross platform and can be packaged with tools like py2exe or py2app.

open cv error: (-215) scn == 3 || scn == 4 in function cvtColor

On OS X I realised, that while cv2.imread can deal with "filename.jpg" it can not process "". Being a novice to python, I can't yet propose a solution, but as François Leblanc wrote, it is more of a silent imread error.

So it has a problem with an additional dot in the filename and propabely other signs as well, as with " " (Space) or "%" and so on.

how to calculate binary search complexity

A binary search works by dividing the problem in half repeatedly, something like this (details omitted):

Example looking for 3 in [4,1,3,8,5]

  1. Order your list of items [1,3,4,5,8]
  2. Look at the middle item (4),
    • If it is what you are looking for, stop
    • If it is greater, look at the first half
    • If it is less, look at the second half
  3. Repeat step 2 with the new list [1, 3], find 3 and stop

It is a bi-nary search when you divide the problem in 2.

The search only requires log2(n) steps to find the correct value.

I would recommend Introduction to Algorithms if you want to learn about algorithmic complexity.

T-SQL substring - separating first and last name

The code below works with Last, First M name strings. Substitute "Name" with your name string column name. Since you have a period as a final character when there is a middle initial, you would replace the 2's with 3's in each of the lines (2, 6, and 8)- and change "RIGHT(Name, 1)" to "RIGHT(Name, 2)" in line 8.

SELECT  SUBSTRING(Name, 1, CHARINDEX(',', Name) - 1) LastName ,
CASE WHEN LEFT(RIGHT(Name, 2), 1) <> ' '
     THEN LTRIM(SUBSTRING(Name, CHARINDEX(',', Name) + 1, 99))
     ELSE LEFT(LTRIM(SUBSTRING(Name, CHARINDEX(',', Name) + 1, 99)),
               LEN(LTRIM(SUBSTRING(Name, CHARINDEX(',', Name) + 1, 99)))
               - 2)
END FirstName ,
CASE WHEN LEFT(RIGHT(Name, 2), 1) = ' ' THEN RIGHT(Name, 1)
END MiddleName

.includes() not working in Internet Explorer

Or just put this in a Javascript file and have a good day :)

String.prototype.includes = function (str) {
  var returnValue = false;

  if (this.indexOf(str) !== -1) {
    returnValue = true;

  return returnValue;

C# DataTable.Select() - How do I format the filter criteria to include null?

The way to check for null is to check for it:

DataRow[] myResultSet = myDataTable.Select("[COLUMN NAME] is null");

You can use and and or in the Select statement.

Export MySQL data to Excel in PHP

This is new version of php code

$servername = "localhost";
$username = "root";
$password = "";
$dbname = "your_dbname";
//mysql and db connection

$con = new mysqli($servername, $username, $password, $dbname);

if ($con->connect_error) {  //error check
    die("Connection failed: " . $con->connect_error);


$DB_TBLName = "your_table_name"; 
$filename = "excelfilename";  //your_file_name
$file_ending = "xls";   //file_extention

header("Content-Type: application/xls");    
header("Content-Disposition: attachment; filename=$filename.'.'.$file_ending");  
header("Pragma: no-cache"); 
header("Expires: 0");

$sep = "\t";

$sql="SELECT * FROM $DB_TBLName"; 
$resultt = $con->query($sql);
while ($property = mysqli_fetch_field($resultt)) { //fetch table field name
    echo $property->name."\t";


while($row = mysqli_fetch_row($resultt))  //fetch_table_data
    $schema_insert = "";
    for($j=0; $j< mysqli_num_fields($resultt);$j++)
            $schema_insert .= "NULL".$sep;
        elseif ($row[$j] != "")
            $schema_insert .= "$row[$j]".$sep;
            $schema_insert .= "".$sep;
    $schema_insert = str_replace($sep."$", "", $schema_insert);
    $schema_insert = preg_replace("/\r\n|\n\r|\n|\r/", " ", $schema_insert);
    $schema_insert .= "\t";
    print "\n";

How to use regex in String.contains() method in Java

If you want to check if a string contains substring or not using regex, the closest you can do is by using find() -

    private static final validPattern =   "\\bstores\\b.*\\bstore\\b.*\\bproduct\\b"
    Pattern pattern = Pattern.compile(validPattern);
    Matcher matcher = pattern.matcher(inputString);
    System.out.print(matcher.find()); // should print true or false.

Note the difference between matches() and find(), matches() return true if the whole string matches the given pattern. find() tries to find a substring that matches the pattern in a given input string. Also by using find() you don't have to add extra matching like - (?s).* at the beginning and .* at the end of your regex pattern.

How can I select all options of multi-select select box on click?

Working Demo

$('#select_all').click( function() {
    $('select#countries > option').prop('selected', 'selected');

If you use jQuery older than 1.6:

$('#select_all').click( function() {
    $('select#countries > option').attr('selected', 'selected');

How can I use iptables on centos 7?

Put the IPtables configuration in the traditional file and it will be loaded after boot:


How to get value of checked item from CheckedListBox?

EDIT: I realized a little late that it was bound to a DataTable. In that case the idea is the same, and you can cast to a DataRowView then take its Row property to get a DataRow if you want to work with that class.

foreach (var item in checkedListBox1.CheckedItems)
    var row = (item as DataRowView).Row;
    MessageBox.Show(row["ID"] + ": " + row["CompanyName"]);

You would need to cast or parse the items to their strongly typed equivalents, or use the System.Data.DataSetExtensions namespace to use the DataRowExtensions.Field method demonstrated below:

foreach (var item in checkedListBox1.CheckedItems)
    var row = (item as DataRowView).Row;
    int id = row.Field<int>("ID");
    string name = row.Field<string>("CompanyName");
    MessageBox.Show(id + ": " + name);

You need to cast the item to access the properties of your class.

foreach (var item in checkedListBox1.CheckedItems)
    var company = (Company)item;
    MessageBox.Show(company.Id + ": " + company.CompanyName);

Alternately, you could use the OfType extension method to get strongly typed results back without explicitly casting within the loop:

foreach (var item in checkedListBox1.CheckedItems.OfType<Company>())
    MessageBox.Show(item.Id + ": " + item.CompanyName);

Currently running queries in SQL Server

The tool is called the SQL Server Profiler, it's still part of the standard toolset.

How to convert a Drawable to a Bitmap?

This piece of code helps.

Bitmap icon = BitmapFactory.decodeResource(context.getResources(),

Here a version where the image gets downloaded.

String name = c.getString(str_url);
URL url_value = new URL(name);
ImageView profile = (ImageView)v.findViewById(;
if (profile != null) {
    Bitmap mIcon1 =

Using a PHP variable in a text input value = statement

From the HTML point of view everything's been said, but to correct the PHP-side approach a little and taking thirtydot's and icktoofay's advice into account:

<?php echo '<input type="text" name="idtest" value="' . htmlspecialchars($idtest) . '">'; ?>

Is there a CSS selector for text nodes?

You cannot target text nodes with CSS. I'm with you; I wish you could... but you can't :(

If you don't wrap the text node in a <span> like @Jacob suggests, you could instead give the surrounding element padding as opposed to margin:


<p id="theParagraph">The text node!</p>


    border: 1px solid red;
    padding-bottom: 10px;

Restrict varchar() column to specific values?

Personally, I'd code it as tinyint and:

  • Either: change it to text on the client, check constraint between 1 and 4
  • Or: use a lookup table with a foreign key


  • It will take on average 8 bytes to store text, 1 byte for tinyint. Over millions of rows, this will make a difference.

  • What about collation? Is "Daily" the same as "DAILY"? It takes resources to do this kind of comparison.

  • Finally, what if you want to add "Biweekly" or "Hourly"? This requires a schema change when you could just add new rows to a lookup table.

How to import the class within the same directory or sub directory?

If and are not including classes then

from .user import User
from .dir import Dir

is not working. You should then import as

from . import user
from . import dir

How can I find the version of php that is running on a distinct domain name?

By chance: Default error pages often contain detailed information, e.g.

Apache/{Version} ({OS}) {Modules} PHP/{Version} {Modules} Server at {Domain}

Not so easy: Find out which versions of PHP applications run on the server and which version of PHP they require.

Another approach, only mentioned for the sake of completeness; please forget after reading: You could (but you won't!) detect the PHP version by trying known exploits.

Change Orientation of Bluestack : portrait/landscape mode

You could also change resolution of your bluestacks emulator. For example from 800x1280 to 1280x800

Here are instructions for how to change the screen resolution.

To change screen resolution in BlueStacks Android emulator you need to edit two registry items:

  1. Run regedit.exe

  2. Set new resolution (in decimal):




Kill all BlueStacks processes.

Restart BlueStacks

MySQL: Insert datetime into other datetime field


    UPDATE products SET former_date=20111218131717 WHERE id=1

Alternatively, you might want to look at using the STR_TO_DATE (see STR_TO_DATE(str,format)) function.

How to display an IFRAME inside a jQuery UI dialog

Although this is a old post, I have spent 3 hours to fix my issue and I think this might help someone in future.

Here is my jquery-dialog hack to show html content inside an <iframe> :

let modalProperties = {autoOpen: true, width: 900, height: 600, modal: true, title: 'Modal Title'};
let modalHtmlContent = '<div>My Content First div</div><div>My Content Second div</div>';

// create wrapper iframe
let wrapperIframe = $('<iframe src="" frameborder="0" style="width:100%; height:100%;"></iframe>');

// create jquery dialog by a 'div' with 'iframe' appended

// insert html content to iframe 'body'
let wrapperIframeDocument = wrapperIframe[0].contentDocument;
let wrapperIframeBody = $('body', wrapperIframeDocument);

jsfiddle demo

How can I open a URL in Android's web browser from my application?

other option In Load Url in Same Application using Webview

webView = (WebView) findViewById(;

How to convert a NumPy array to PIL image applying matplotlib colormap

  • input = numpy_image
  • np.unit8 -> converts to integers
  • convert('RGB') -> converts to RGB
  • Image.fromarray -> returns an image object

    from PIL import Image
    import numpy as np
    PIL_image = Image.fromarray(np.uint8(numpy_image)).convert('RGB')
    PIL_image = Image.fromarray(numpy_image.astype('uint8'), 'RGB')

How to show all rows by default in JQuery DataTable


    aLengthMenu: [
        [25, 50, 100, 200, -1],
        [25, 50, 100, 200, "All"]
    iDisplayLength: -1

Or if using 1.10+

    paging: false

The option you should use is iDisplayLength:

  'iDisplayLength': 100

   "lengthMenu": [ [5, 10, 25, 50, -1], [5, 10, 25, 50, "All"] ]

It will Load by default all entries.

    aLengthMenu: [
        [25, 50, 100, 200, -1],
        [25, 50, 100, 200, "All"]
    iDisplayLength: -1

Or if using 1.10+

    paging: false

If you want to load by default 25 not all do this.

    aLengthMenu: [
        [25, 50, 100, 200, -1],
        [25, 50, 100, 200, "All"]

Best practices when running Node.js with port 80 (Ubuntu / Linode)

Port 80

What I do on my cloud instances is I redirect port 80 to port 3000 with this command:

sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3000

Then I launch my Node.js on port 3000. Requests to port 80 will get mapped to port 3000.

You should also edit your /etc/rc.local file and add that line minus the sudo. That will add the redirect when the machine boots up. You don't need sudo in /etc/rc.local because the commands there are run as root when the system boots.


Use the forever module to launch your Node.js with. It will make sure that it restarts if it ever crashes and it will redirect console logs to a file.

Launch on Boot

Add your Node.js start script to the file you edited for port redirection, /etc/rc.local. That will run your Node.js launch script when the system starts.

Digital Ocean & other VPS

This not only applies to Linode, but Digital Ocean, AWS EC2 and other VPS providers as well. However, on RedHat based systems /etc/rc.local is /ect/rc.d/local.

How to read integer value from the standard input in Java

Here I am providing 2 examples to read integer value from the standard input

Example 1

import java.util.Scanner;
public class Maxof2
  public static void main(String args[])
       //taking value as command line argument.
        Scanner in = new Scanner(; 
       System.out.printf("Enter i Value:  ");
       int i = in.nextInt();
       System.out.printf("Enter j Value:  ");
       int j = in.nextInt();
       if(i > j)
           System.out.println(i+"i is greater than "+j);
           System.out.println(j+" is greater than "+i);

Example 2

public class ReadandWritewhateveryoutype
  public static void main(String args[]) throws java.lang.Exception
System.out.printf("This Program is used to Read and Write what ever you type \nType  quit  to Exit at any Moment\n\n"); r = new (new (;
     String hi;
     while (!(hi=r.readLine()).startsWith("quit"))System.out.printf("\nYou have typed: %s \n",hi);

I prefer the First Example, it's easy and quite understandable.
You can compile and run the JAVA programs online at this website:

Enable tcp\ip remote connections to sql server express already installed database with code or script(query)

I recommend to use SMO (Enable TCP/IP Network Protocol for SQL Server). However, it was not available in my case.

I rewrote the WMI commands from Krzysztof Kozielczyk to PowerShell.

# Enable TCP/IP

Get-CimInstance -Namespace root/Microsoft/SqlServer/ComputerManagement10 -ClassName ServerNetworkProtocol -Filter "InstanceName = 'SQLEXPRESS' and ProtocolName = 'Tcp'" |
Invoke-CimMethod -Name SetEnable

# Open the right ports in the firewall
New-NetFirewallRule -DisplayName 'MSSQL$SQLEXPRESS' -Direction Inbound -Action Allow -Protocol TCP -LocalPort 1433

# Modify TCP/IP properties to enable an IP address

$properties = Get-CimInstance -Namespace root/Microsoft/SqlServer/ComputerManagement10 -ClassName ServerNetworkProtocolProperty -Filter "InstanceName='SQLEXPRESS' and ProtocolName = 'Tcp' and IPAddressName='IPAll'"
$properties | ? { $_.PropertyName -eq 'TcpPort' } | Invoke-CimMethod -Name SetStringValue -Arguments @{ StrValue = '1433' }
$properties | ? { $_.PropertyName -eq 'TcpPortDynamic' } | Invoke-CimMethod -Name SetStringValue -Arguments @{ StrValue = '' }

# Restart SQL Server

Restart-Service 'MSSQL$SQLEXPRESS'

Convert double to float in Java


disable a hyperlink using jQuery

I know it's an old question but it seems unsolved still. Follows my solution...

Simply add this global handler:

     return ($(this).attr('disabled')) ? false : true;

Here's a quick demo:

you can even add a bit of css to give a different style to all the links with the disabled attribute.


    color: grey; 

Anyway it seems that the disabled attribute is not valid for a tags. If you prefer to follow the w3c specs you can easily adopt an html5 compliant data-disabled attribute. In this case you have to modify the previous snippet and use $(this).data('disabled').

How do I get the function name inside a function in PHP?

The accurate way is to use the __FUNCTION__ predefined magic constant.


class Test {
    function MethodA(){
        echo __FUNCTION__;

Result: MethodA.

Warning: mysqli_real_escape_string() expects exactly 2 parameters, 1 given... what I do wrong?

You are mixing mysqli and mysql function.

If your are using mysql function then instead mysqli_real_escape_string($your_variable); use

$username = mysql_real_escape_string($_POST['username']);
$pass = mysql_real_escape_string($_POST['pass']);
$pass1 = mysql_real_escape_string($_POST['pass1']);
$email = mysql_real_escape_string($_POST['email']);

If your using mysqli_* function then you have to include your connection to database into mysqli_real_escape function :

$username = mysqli_real_escape_string($your_connection, $_POST['username']);
$pass = mysqli_real_escape_string($your_connection, $_POST['pass']);
$pass1 = mysqli_real_escape_string($your_connection, $_POST['pass1']);
$email = mysqli_real_escape_string($your_connection, $_POST['email']);

Note : Use mysqli_* function since mysql has been deprecated. For information please read mysqli_*

How to stop default link click behavior with jQuery



Cancels the event if it is cancelable, without stopping further propagation of the event.

Why is SQL Server 2008 Management Studio Intellisense not working?

I tried all the fixes - taking databases offline and then bringing them online, installed Cumulative update 10, repaired SQL Server Installation, refreshed local cache, made changes to the required settings on SQL Server Management Studio but everything was in vain. Finally installing the correct service pack (SP1) did the trick for me !

Follow the link below, and download SQLServer2008R2SP1-KB2528583-x86-ENU.exe (or the x64 file for a x64 bit instance of SQL Server)

Finally i have Intellisense enabled !

How to generate a Makefile with source in sub-directories using just one makefile

Usually, you create a Makefile in each subdirectory, and write in the top-level Makefile to call make in the subdirectories.

This page may help:

How do you install an APK file in the Android emulator?

Copy .apk file in your SDK's platform-tools/ directory,then install the .apk on the emulator by using cmd(on windows):

adb install <path_to_your_bin>.apk


./adb install <path_to_your_bin>.apk

If there is more than one emulator running, you can find all running emulators by this command:

adb devices


./adb devices

then you must specify the emulator upon which to install the application, by its serial number, with the -s option. For example:

adb -s emulator-5554 install path/to/your/app.apk


./adb -s emulator-5554 install path/to/your/app.apk

How do you run JavaScript script through the Terminal?

Technically, Node.js isn't proper JavaScript as we know it, since there isn't a Document Object Model (DOM). For instance, JavaScript scripts that run in the browser will not work. At all. The solution would be to run JavaScript with a headless browser. Fortunately there is a project still active: Mozilla Firefox has a headless mode.

$ /Applications/ -headless index.html
*** You are running in headless mode.

When to use: Java 8+ interface default method, vs. abstract method

These two are quite different:

Default methods are to add external functionality to existing classes without changing their state.

And abstract classes are a normal type of inheritance, they are normal classes which are intended to be extended.

SQL Server: Multiple table joins with a WHERE clause

try this

INSERT @Application ( Id, NAME )
VALUES  ( 1,'Word' ), ( 2,'Excel' ), ( 3,'PowerPoint' )
DECLARE @software TABLE(Id INT PRIMARY KEY, ApplicationId INT, Version INT)
INSERT @software ( Id, ApplicationId, Version )
VALUES  ( 1,1, 2003 ), ( 2,1,2007 ), ( 3,2, 2003 ), ( 4,2,2007 ),( 5,3, 2003 ), ( 6,3,2007 )

INSERT @Computer ( Id, NAME )
VALUES  ( 1,'Name1' ), ( 2,'Name2' )

DECLARE @Software_Computer  TABLE(Id INT PRIMARY KEY, SoftwareId int, ComputerId int)
INSERT @Software_Computer ( Id, SoftwareId, ComputerId )
VALUES  ( 1,1, 1 ), ( 2,4,1 ), ( 3,2, 2 ), ( 4,5,2 )

SELECT Computer.Name ComputerName, Application.Name ApplicationName, MAX(Software2.Version) Version
FROM @Application Application 
JOIN @Software Software
    ON Application.ID = Software.ApplicationID
CROSS JOIN @Computer Computer
LEFT JOIN @Software_Computer Software_Computer
    ON Software_Computer.ComputerId = Computer.Id AND Software_Computer.SoftwareId = Software.Id
LEFT JOIN @Software Software2
    ON Software2.ID = Software_Computer.SoftwareID
WHERE Computer.ID = 1 
GROUP BY Computer.Name, Application.Name

How do I store and retrieve a blob from sqlite?

This worked fine for me (C#):

byte[] iconBytes = null;
using (var dbConnection = new SQLiteConnection(DataSource))
    using (var transaction = dbConnection.BeginTransaction())
        using (var command = new SQLiteCommand(dbConnection))
            command.CommandText = "SELECT icon FROM my_table";

            using (var reader = command.ExecuteReader())
                while (reader.Read())
                    if (reader["icon"] != null && !Convert.IsDBNull(reader["icon"]))
                        iconBytes = (byte[]) reader["icon"];

No need for chunking. Just cast to a byte array.

python JSON object must be str, bytes or bytearray, not 'dict

json.dumps() is used to decode JSON data

import json

# initialize different data
str_data = 'normal string'
int_data = 1
float_data = 1.50
list_data = [str_data, int_data, float_data]
nested_list = [int_data, float_data, list_data]
dictionary = {
    'int': int_data,
    'str': str_data,
    'float': float_data,
    'list': list_data,
    'nested list': nested_list

# convert them to JSON data and then print it
print('String :', json.dumps(str_data))
print('Integer :', json.dumps(int_data))
print('Float :', json.dumps(float_data))
print('List :', json.dumps(list_data))
print('Nested List :', json.dumps(nested_list, indent=4))
print('Dictionary :', json.dumps(dictionary, indent=4))  # the json data will be indented


String : "normal string"
Integer : 1
Float : 1.5
List : ["normal string", 1, 1.5]
Nested List : [
        "normal string",
Dictionary : {
    "int": 1,
    "str": "normal string",
    "float": 1.5,
    "list": [
        "normal string",
    "nested list": [
            "normal string",
  • Python Object to JSON Data Conversion
|                 Python                 |  JSON  |
|                  dict                  | object |
|               list, tuple              |  array |
|                   str                  | string |
| int, float, int- & float-derived Enums | number |
|                  True                  |  true  |
|                  False                 |  false |
|                  None                  |  null  |

json.loads() is used to convert JSON data into Python data.

import json

# initialize different JSON data
arrayJson = '[1, 1.5, ["normal string", 1, 1.5]]'
objectJson = '{"a":1, "b":1.5 , "c":["normal string", 1, 1.5]}'

# convert them to Python Data
list_data = json.loads(arrayJson)
dictionary = json.loads(objectJson)

print('arrayJson to list_data :\n', list_data)
print('\nAccessing the list data :')
print('list_data[2:] =', list_data[2:])
print('list_data[:1] =', list_data[:1])

print('\nobjectJson to dictionary :\n', dictionary)
print('\nAccessing the dictionary :')
print('dictionary[\'a\'] =', dictionary['a'])
print('dictionary[\'c\'] =', dictionary['c'])


arrayJson to list_data :
 [1, 1.5, ['normal string', 1, 1.5]]

Accessing the list data :
list_data[2:] = [['normal string', 1, 1.5]]
list_data[:1] = [1]

objectJson to dictionary :
 {'a': 1, 'b': 1.5, 'c': ['normal string', 1, 1.5]}

Accessing the dictionary :
dictionary['a'] = 1
dictionary['c'] = ['normal string', 1, 1.5]
  • JSON Data to Python Object Conversion
|      JSON     | Python |
|     object    |  dict  |
|     array     |  list  |
|     string    |   str  |
|  number (int) |   int  |
| number (real) |  float |
|      true     |  True  |
|     false     |  False |

SQL JOIN, GROUP BY on three tables to get totals

First of all, shouldn't there be a CustomerId in the Invoices table? As it is, You can't perform this query for Invoices that have no payments on them as yet. If there are no payments on an invoice, that invoice will not even show up in the ouput of the query, even though it's an outer join...

Also, When a customer makes a payment, how do you know what Invoice to attach it to ? If the only way is by the InvoiceId on the stub that arrives with the payment, then you are (perhaps inappropriately) associating Invoices with the customer that paid them, rather than with the customer that ordered them... . (Sometimes an invoice can be paid by someone other than the customer who ordered the services)

Pip error: Microsoft Visual C++ 14.0 is required

I got this error when I tried to install pymssql even though Visual C++ 2015 (14.0) is installed in my system.

I resolved this error by downloading the .whl file of pymssql from here.

Once downloaded, it can be installed by the following command :

pip install python_package.whl

Hope this helps

How to let an ASMX file output JSON

Are you calling the web service from client script or on the server side?

You may find sending a content type header to the server will help, e.g.

'application/json; charset=utf-8'

On the client side, I use prototype client side library and there is a contentType parameter when making an Ajax call where you can specify this. I think jQuery has a getJSON method.

Simple way to repeat a string

Using recursion, you can do the following (using ternary operators, one line max):

public static final String repeat(String string, long number) {
    return number == 1 ? string : (number % 2 == 0 ? repeat(string + string, number / 2) : string + repeat(string + string, (number - 1) / 2));

I know, it's ugly and probably not efficient, but it's one line!

Oracle JDBC ojdbc6 Jar as a Maven Dependency

Below config worked for me. Refer this link for more details.


What is the difference between HTTP status code 200 (cache) vs status code 304?

The items with code "200 (cache)" were fulfilled directly from your browser cache, meaning that the original requests for the items were returned with headers indicating that the browser could cache them (e.g. future-dated Expires or Cache-Control: max-age headers), and that at the time you triggered the new request, those cached objects were still stored in local cache and had not yet expired.

304s, on the other hand, are the response of the server after the browser has checked if a file was modified since the last version it had cached (the answer being "no").

For most optimal web performance, you're best off setting a far-future Expires: or Cache-Control: max-age header for all assets, and then when an asset needs to be changed, changing the actual filename of the asset or appending a version string to requests for that asset. This eliminates the need for any request to be made unless the asset has definitely changed from the version in cache (no need for that 304 response). Google has more details on correct use of long-term caching.

Python Socket Multiple Clients

import sys
import os
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)         
port = 50000

    s.bind((socket.gethostname() , port))
except socket.error as msg:
conn, addr = s.accept()  
print 'Got connection from'+addr[0]+':'+str(addr[1]))
while 1:
        msg = s.recv(1024)
        print +addr[0]+, ' >> ', msg
        msg = raw_input('SERVER >>'),host

How to send parameters with jquery $.get()

This is what worked for me:

    method: 'GET',
    url: 'api.php',
    headers: {
        'Content-Type': 'application/json',
    // query parameters go under "data" as an Object
    data: {
        client: 'mikescafe'

will make a REST/AJAX call - > GET http://localhost:3000/api.php?client=mikescafe

Good Luck.

Access is denied when attaching a database

With me - Running on window 8 - RIght click SQL Server Manager Studio -> Run with admin. -> attach no problems

AngularJs ReferenceError: angular is not defined

In case you'd happen to be using rails and the angular-rails gem then the problem is easily corrected by adding this missing line to application.js (or what ever is applicable in your situation):

//= require angular-resource

How to pass all arguments passed to my bash script to a function of mine?

The $@ variable expands to all command-line parameters separated by spaces. Here is an example.

abc "$@"

When using $@, you should (almost) always put it in double-quotes to avoid misparsing of arguments containing spaces or wildcards (see below). This works for multiple arguments. It is also portable to all POSIX-compliant shells.

It is also worth nothing that $0 (generally the script's name or path) is not in $@.

The Bash Reference Manual Special Parameters Section says that $@ expands to the positional parameters starting from one. When the expansion occurs within double quotes, each parameter expands to a separate word. That is "$@" is equivalent to "$1" "$2" "$3"....

Passing some arguments:

If you want to pass all but the first arguments, you can first use shift to "consume" the first argument and then pass "$@" to pass the remaining arguments to another command. In bash (and zsh and ksh, but not in plain POSIX shells like dash), you can do this without messing with the argument list using a variant of array slicing: "${@:3}" will get you the arguments starting with "$3". "${@:3:4}" will get you up to four arguments starting at "$3" (i.e. "$3" "$4" "$5" "$6"), if that many arguments were passed.

Things you probably don't want to do:

"$*" gives all of the arguments stuck together into a single string (separated by spaces, or whatever the first character of $IFS is). This looses the distinction between spaces within arguments and the spaces between arguments, so is generally a bad idea. Although it might be ok for printing the arguments, e.g. echo "$*", provided you don't care about preserving the space within/between distinction.

Assigning the arguments to a regular variable (as in args="$@") mashes all the arguments together just like "$*" does. If you want to store the arguments in a variable, use an array with args=("$@") (the parentheses make it an array), and then reference them as e.g. "${args[0]}" etc (note that bash array indexes start at 0, so $1 will be in args[0], etc).

Leaving off the double-quotes, with either $@ or $*, will try to split each argument up into separate words (based on whitespace or whatever's in $IFS), and also try to expand anything that looks like a filename wildcard into a list of matching filenames. This can have really weird effects, and should almost always be avoided.

Read text file into string array (and write)

If you don't care about loading the file into memory, as of Go 1.16, you can use the os.ReadFile and bytes.Count functions.

package main

import (

func main() {
    data, err := os.ReadFile("input.txt")
    if err != nil {

    n := bytes.Count(data, []byte{'\n'})

    fmt.Printf("input.txt has %d lines\n", n)

getCurrentPosition() and watchPosition() are deprecated on insecure origins

Use FireFox or any other browser instead of Chrome if you want to test it on your development environment, for production there is no way except using https.

For development environment just open http://localhost:8100/ on FireFox and alas no such error.

git pull displays "fatal: Couldn't find remote ref refs/heads/xxxx" and hangs up

To pull a remote branch locally, I do the following:

git checkout -b branchname // creates a local branch with the same name and checks out on it

git pull origin branchname // pulls the remote one onto your local one

The only time I did this and it didn't work, I deleted the repo, cloned it again and repeated the above 2 steps; it worked.

jQuery - Add ID instead of Class

Try this:

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

So it becomes;

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

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

When to encode space to plus (+) or %20?

+ means a space only in application/x-www-form-urlencoded content, such as the query part of a URL:

In this URL, the parameter name is query name with a space and the value is query value with a space, but the folder name in the path is literally foo+bar, not foo bar.

%20 is a valid way to encode a space in either of these contexts. So if you need to URL-encode a string for inclusion in part of a URL, it is always safe to replace spaces with %20 and pluses with %2B. This is what eg. encodeURIComponent() does in JavaScript. Unfortunately it's not what urlencode does in PHP (rawurlencode is safer).

See Also HTML 4.01 Specification application/x-www-form-urlencoded

Laravel-5 'LIKE' equivalent (Eloquent)

I think this is better, following the good practices of passing parameters to the query:

BookingDates::whereRaw('email = ? or name like ?', [$request->email,"%{$request->name}%"])->get();

You can see it in the documentation, Laravel 5.5.

You can also use the Laravel scout and make it easier with search. Here is the documentation.

What are the options for storing hierarchical data in a relational database?

I am using PostgreSQL with closure tables for my hierarchies. I have one universal stored procedure for the whole database:

CREATE FUNCTION nomen_tree() RETURNS trigger
    LANGUAGE plpgsql
    AS $_$
  old_parent INTEGER;
  new_parent INTEGER;
  id_nom INTEGER;
  txt_name TEXT;
-- TG_ARGV[0] = name of table with entities with PARENT-CHILD relationships (TBL_ORIG)
-- TG_ARGV[1] = name of helper table with ANCESTOR, CHILD, DEPTH information (TBL_TREE)
-- TG_ARGV[2] = name of the field in TBL_ORIG which is used for the PARENT-CHILD relationship (FLD_PARENT)
    EXECUTE 'INSERT INTO ' || TG_ARGV[1] || ' (child_id,ancestor_id,depth) 
        SELECT $,$,0 UNION ALL
      SELECT $,ancestor_id,depth+1 FROM ' || TG_ARGV[1] || ' WHERE child_id=$1.' || TG_ARGV[2] USING NEW;
    -- EXECUTE does not support conditional statements inside
    EXECUTE 'SELECT $1.' || TG_ARGV[2] || ',$2.' || TG_ARGV[2] INTO old_parent,new_parent USING OLD,NEW;
    IF COALESCE(old_parent,0) <> COALESCE(new_parent,0) THEN
      EXECUTE '
      -- prevent cycles in the tree
      UPDATE ' || TG_ARGV[0] || ' SET ' || TG_ARGV[2] || ' = $1.' || TG_ARGV[2]
        || ' WHERE id=$2.' || TG_ARGV[2] || ' AND EXISTS(SELECT 1 FROM '
        || TG_ARGV[1] || ' WHERE child_id=$2.' || TG_ARGV[2] || ' AND ancestor_id=$;
      -- first remove edges between all old parents of node and its descendants
      DELETE FROM ' || TG_ARGV[1] || ' WHERE child_id IN
        (SELECT child_id FROM ' || TG_ARGV[1] || ' WHERE ancestor_id = $
        AND ancestor_id IN
        (SELECT ancestor_id FROM ' || TG_ARGV[1] || ' WHERE child_id = $ AND ancestor_id <> $;
      -- then add edges for all new parents ...
      INSERT INTO ' || TG_ARGV[1] || ' (child_id,ancestor_id,depth) 
        SELECT child_id,ancestor_id,d_c+d_a FROM
        (SELECT child_id,depth AS d_c FROM ' || TG_ARGV[1] || ' WHERE ancestor_id=$ AS child
        CROSS JOIN
        (SELECT ancestor_id,depth+1 AS d_a FROM ' || TG_ARGV[1] || ' WHERE child_id=$2.' 
        || TG_ARGV[2] || ') AS parent;' USING OLD, NEW;
    END IF;

Then for each table where I have a hierarchy, I create a trigger

CREATE TRIGGER nomenclature_tree_tr AFTER INSERT OR UPDATE ON nomenclature FOR EACH ROW EXECUTE PROCEDURE nomen_tree('my_db.nomenclature', 'my_db.nom_helper', 'parent_id');

For populating a closure table from existing hierarchy I use this stored procedure:

CREATE FUNCTION rebuild_tree(tbl_base text, tbl_closure text, fld_parent text) RETURNS void
    LANGUAGE plpgsql
    AS $$
    EXECUTE 'TRUNCATE ' || tbl_closure || ';
    INSERT INTO ' || tbl_closure || ' (child_id,ancestor_id,depth) 
        WITH RECURSIVE tree AS
        SELECT id AS child_id,id AS ancestor_id,0 AS depth FROM ' || tbl_base || '
        UNION ALL 
        SELECT,ancestor_id,depth+1 FROM ' || tbl_base || ' AS t
        JOIN tree ON child_id = ' || fld_parent || '
      SELECT * FROM tree;';

Closure tables are defined with 3 columns - ANCESTOR_ID, DESCENDANT_ID, DEPTH. It is possible (and I even advice) to store records with same value for ANCESTOR and DESCENDANT, and a value of zero for DEPTH. This will simplify the queries for retrieval of the hierarchy. And they are very simple indeed:

-- get all descendants
SELECT tbl_orig.*,depth FROM tbl_closure LEFT JOIN tbl_orig ON descendant_id = WHERE ancestor_id = XXX AND depth <> 0;
-- get only direct descendants
SELECT tbl_orig.* FROM tbl_closure LEFT JOIN tbl_orig ON descendant_id = WHERE ancestor_id = XXX AND depth = 1;
-- get all ancestors
SELECT tbl_orig.* FROM tbl_closure LEFT JOIN tbl_orig ON ancestor_id = WHERE descendant_id = XXX AND depth <> 0;
-- find the deepest level of children
SELECT MAX(depth) FROM tbl_closure WHERE ancestor_id = XXX;

creating a table in ionic


.table:nth-child(2n+1) {
    background-color: whatever color !important;


    <ion-row class="nameClass" justify-content-center align-items-center style='height: 100%'>

            <div text-center>

row 2

        <ion-col >

        <ion-col >

        <ion-col >




How to load a jar file at runtime

Reloading existing classes with existing data is likely to break things.

You can load new code into new class loaders relatively easily:

ClassLoader loader = URLClassLoader.newInstance(
    new URL[] { yourURL },
Class<?> clazz = Class.forName("mypackage.MyClass", true, loader);
Class<? extends Runnable> runClass = clazz.asSubclass(Runnable.class);
// Avoid Class.newInstance, for it is evil.
Constructor<? extends Runnable> ctor = runClass.getConstructor();
Runnable doRun = ctor.newInstance();;

Class loaders no longer used can be garbage collected (unless there is a memory leak, as is often the case with using ThreadLocal, JDBC drivers, java.beans, etc).

If you want to keep the object data, then I suggest a persistence mechanism such as Serialisation, or whatever you are used to.

Of course debugging systems can do fancier things, but are more hacky and less reliable.

It is possible to add new classes into a class loader. For instance, using URLClassLoader.addURL. However, if a class fails to load (because, say, you haven't added it), then it will never load in that class loader instance.

HTML code for an apostrophe

Although the &apos; entity may be supported in HTML5, it looks like a typewriter apostrophe. It looks nothing like a real curly apostrophe—which looks identical to an ending quotation mark: .

Just look when I write them after each other:

1: right single quotation mark entity, 2: apostrophe entity: '.

I tried to find a proper entity or alt command specifically for a normal looking apostrophe (which again, looks ‘identical’ to a closing right single quotation mark), but I haven’t found one. I always need to insert a right single quotation mark in order to get the visually correct apostrophe.

If you use just (ALT + 0146) or autoformat typewriter apostrophes and quotation marks as curly in a word processor like Word 2013, do use <meta charset="UTF-8">.

How should I declare default values for instance variables in Python?

Using class members to give default values works very well just so long as you are careful only to do it with immutable values. If you try to do it with a list or a dict that would be pretty deadly. It also works where the instance attribute is a reference to a class just so long as the default value is None.

I've seen this technique used very successfully in repoze which is a framework that runs on top of Zope. The advantage here is not just that when your class is persisted to the database only the non-default attributes need to be saved, but also when you need to add a new field into the schema all the existing objects see the new field with its default value without any need to actually change the stored data.

I find it also works well in more general coding, but it's a style thing. Use whatever you are happiest with.

What does asterisk * mean in Python?

See Function Definitions in the Language Reference.

If the form *identifier is present, it is initialized to a tuple receiving any excess positional parameters, defaulting to the empty tuple. If the form **identifier is present, it is initialized to a new dictionary receiving any excess keyword arguments, defaulting to a new empty dictionary.

Also, see Function Calls.

Assuming that one knows what positional and keyword arguments are, here are some examples:

Example 1:

# Excess keyword argument (python 2) example:
def foo(a, b, c, **args):
    print "a = %s" % (a,)
    print "b = %s" % (b,)
    print "c = %s" % (c,)
    print args

foo(a="testa", d="excess", c="testc", b="testb", k="another_excess")

As you can see in the above example, we only have parameters a, b, c in the signature of the foo function. Since d and k are not present, they are put into the args dictionary. The output of the program is:

a = testa
b = testb
c = testc
{'k': 'another_excess', 'd': 'excess'}

Example 2:

# Excess positional argument (python 2) example:
def foo(a, b, c, *args):
    print "a = %s" % (a,)
    print "b = %s" % (b,)
    print "c = %s" % (c,)
    print args

foo("testa", "testb", "testc", "excess", "another_excess")

Here, since we're testing positional arguments, the excess ones have to be on the end, and *args packs them into a tuple, so the output of this program is:

a = testa
b = testb
c = testc
('excess', 'another_excess')

You can also unpack a dictionary or a tuple into arguments of a function:

def foo(a,b,c,**args):
    print "a=%s" % (a,)
    print "b=%s" % (b,)
    print "c=%s" % (c,)
    print "args=%s" % (args,)

argdict = dict(a="testa", b="testb", c="testc", excessarg="string")


args={'excessarg': 'string'}


def foo(a,b,c,*args):
    print "a=%s" % (a,)
    print "b=%s" % (b,)
    print "c=%s" % (c,)
    print "args=%s" % (args,)

argtuple = ("testa","testb","testc","excess")



Date ticks and rotation in matplotlib

If you prefer a non-object-oriented approach, move plt.xticks(rotation=70) to right before the two avail_plot calls, eg

avail_plot(axs[0], dates, s1, 'testing', 'green')
avail_plot(axs[1], dates, s1, 'testing2', 'red')

This sets the rotation property before setting up the labels. Since you have two axes here, plt.xticks gets confused after you've made the two plots. At the point when plt.xticks doesn't do anything, plt.gca() does not give you the axes you want to modify, and so plt.xticks, which acts on the current axes, is not going to work.

For an object-oriented approach not using plt.xticks, you can use

plt.setp( axs[1].xaxis.get_majorticklabels(), rotation=70 )

after the two avail_plot calls. This sets the rotation on the correct axes specifically.

Beautiful way to remove GET-variables with PHP?

How about:

preg_replace('/\\?.*/', '', $str)

Can a variable number of arguments be passed to a function?

Yes. You can use *args as a non-keyword argument. You will then be able to pass any number of arguments.

def manyArgs(*arg):
  print "I was called with", len(arg), "arguments:", arg

>>> manyArgs(1)
I was called with 1 arguments: (1,)
>>> manyArgs(1, 2, 3)
I was called with 3 arguments: (1, 2, 3)

As you can see, Python will unpack the arguments as a single tuple with all the arguments.

For keyword arguments you need to accept those as a separate actual argument, as shown in Skurmedel's answer.

How to run server written in js with Node.js

Just try

node server

from cmd prompt in that directory

MVC 3: How to render a view without its layout page when loaded via ajax?

You don't have to create an empty view for this.

In the controller:

if (Request.IsAjaxRequest())
  return PartialView();
  return View();

returning a PartialViewResult will override the layout definition when rendering the respons.

Git log to get commits only for a specific branch

In my situation, we are using Git Flow and GitHub. All you need to do this is: Compare your feature branch with your develop branch on GitHub.

It will show the commits only made to your feature branch.

For example:

In a Django form, how do I make a field readonly (or disabled) so that it cannot be edited?

I ran across a similar problem. It looks like I was able to solve it by defining a "get_readonly_fields" method in my ModelAdmin class.

Something like this:

# In the file

class ItemAdmin(admin.ModelAdmin):

    def get_readonly_display(self, request, obj=None):
        if obj:
            return ['sku']
            return []

The nice thing is that obj will be None when you are adding a new Item, or it will be the object being edited when you are changing an existing Item.

get_readonly_display is documented here:

Failed to load resource: the server responded with a status of 404 (Not Found) error in server

It just means that the server cannot find your image.

Remember The image path must be relative to the CSS file location

Check the path and if the image file exist.

Where can I find WcfTestClient.exe (part of Visual Studio)

If you use "Developer Command Prompt" you can just type WcfTestClient to start it or type where wcftestclient to find the location.

Java Ordered Map

LinkedHashMap maintains the order of the keys.

java.util.LinkedHashMap appears to work just like a normal HashMap otherwise.

Loading existing .html file with android WebView

paste your .html file in assets folder of your project folder. and create an xml file in layout folder with the fol code: my.xml:

<WebView  xmlns:android=""

add fol code in activity

    WebView mWebView = null;
    mWebView = (WebView) findViewById(;
    mWebView.loadUrl("file:///android_asset/new.html"); //new.html is html file name.

Android get current Locale, not default

If you are using the Android Support Library you can use ConfigurationCompat instead of @Makalele's method to get rid of deprecation warnings:

Locale current = ConfigurationCompat.getLocales(getResources().getConfiguration()).get(0);

or in Kotlin:

val currentLocale = ConfigurationCompat.getLocales(resources.configuration)[0]

iOS 10 - Changes in asking permissions of Camera, microphone and Photo Library causing application to crash

You have to add this permission in Info.plist for iOS 10.

Photo :

Key       :  Privacy - Photo Library Usage Description    
Value   :  $(PRODUCT_NAME) photo use

Microphone :

Key        :  Privacy - Microphone Usage Description    
Value    :  $(PRODUCT_NAME) microphone use

Camera :

Key       :  Privacy - Camera Usage Description   
Value   :  $(PRODUCT_NAME) camera use

how to empty recyclebin through command prompt?

Yes, you can Make a Batch file with the following code:

cd \Desktop

echo $Shell = New-Object -ComObject Shell.Application >>FILENAME.ps1
echo $RecBin = $Shell.Namespace(0xA) >>FILENAME.ps1
echo $RecBin.Items() ^| %%{Remove-Item $_.Path -Recurse -Confirm:$false} >>FILENAME.ps1

REM The actual lines being writen are right, exept for the last one, the actual thigs being writen are "$RecBin.Items() | %{Remove-Item $_.Path -Recurse -Confirm:$false}"   
But since | and % screw things up, i had to make some changes.

Powershell.exe -executionpolicy remotesigned -File  C:\Desktop\FILENAME.ps1

This basically creates a powershell script that empties the trash in the \Desktop directory, then runs it.

When and why to 'return false' in JavaScript?

I think a better question is, why in a case where you're evaluating a boolean set of return values, would you NOT use true/false? I mean, you could probably have true/null, true/-1, other misc. Javascript "falsy" values to substitute, but why would you do that?

Regular expression to match balanced parentheses

The answer depends on whether you need to match matching sets of brackets, or merely the first open to the last close in the input text.

If you need to match matching nested brackets, then you need something more than regular expressions. - see @dehmann

If it's just first open to last close see @Zach

Decide what you want to happen with:

abc ( 123 ( foobar ) def ) xyz ) ghij

You need to decide what your code needs to match in this case.

How to read all files in a folder from Java?

Given a baseDir, lists out all the files and directories below it, written iteratively.

    public static List<File> listLocalFilesAndDirsAllLevels(File baseDir) {

    List<File>  collectedFilesAndDirs   = new ArrayList<>();
    Deque<File> remainingDirs           = new ArrayDeque<>();

    if(baseDir.exists()) {

        while(!remainingDirs.isEmpty()) {
            File dir = remainingDirs.removeLast();
            List<File> filesInDir = Arrays.asList(dir.listFiles());
            for(File fileOrDir : filesInDir)  {
                if(fileOrDir.isDirectory()) {

    return collectedFilesAndDirs;

Python strptime() and timezones?

I recommend using python-dateutil. Its parser has been able to parse every date format I've thrown at it so far.

>>> from dateutil import parser
>>> parser.parse("Tue Jun 22 07:46:22 EST 2010")
datetime.datetime(2010, 6, 22, 7, 46, 22, tzinfo=tzlocal())
>>> parser.parse("Fri, 11 Nov 2011 03:18:09 -0400")
datetime.datetime(2011, 11, 11, 3, 18, 9, tzinfo=tzoffset(None, -14400))
>>> parser.parse("Sun")
datetime.datetime(2011, 12, 18, 0, 0)
>>> parser.parse("10-11-08")
datetime.datetime(2008, 10, 11, 0, 0)

and so on. No dealing with strptime() format nonsense... just throw a date at it and it Does The Right Thing.

Update: Oops. I missed in your original question that you mentioned that you used dateutil, sorry about that. But I hope this answer is still useful to other people who stumble across this question when they have date parsing questions and see the utility of that module.

Rendering JSON in controller

For the instance of

render :json => @projects, :include => :tasks

You are stating that you want to render @projects as JSON, and include the association tasks on the Project model in the exported data.

For the instance of

render :json => @projects, :callback => 'updateRecordDisplay'

You are stating that you want to render @projects as JSON, and wrap that data in a javascript call that will render somewhat like:

updateRecordDisplay({'projects' => []})

This allows the data to be sent to the parent window and bypass cross-site forgery issues.

Python 3 Float Decimal Points/Precision

Try this:

num = input("Please input your number: ")

num = float("%0.2f" % (num))


I believe this is a lot simpler. For 1 decimal place use %0.1f. For 2 decimal places use %0.2f and so on.

Or, if you want to reduce it all to 2 lines:

num = float("%0.2f" % (float(input("Please input your number: "))))