Programs & Examples On #Syscache2

SysCache2 is a 2nd level cache provider for NHibernate that can leverage SQL dependency-based expiration. It uses uses ASP.NET cache internally. Requires MS SQL Server 2000 or higher.

How to add multiple values to a dictionary key in python?

How about

a["abc"] = [1, 2]

This will result in:

>>> a
{'abc': [1, 2]}

Is that what you were looking for?

How to convert jsonString to JSONObject in Java

Using org.json library:

try {
     JSONObject jsonObject = new JSONObject("{\"phonetype\":\"N95\",\"cat\":\"WP\"}");
}catch (JSONException err){
     Log.d("Error", err.toString());

Convert factor to integer

You can combine the two functions; coerce to characters thence to numerics:

> fac <- factor(c("1","2","1","2"))
> as.numeric(as.character(fac))
[1] 1 2 1 2

How do I make an html link look like a button?

Simple button css now you can play around with your editor

a {
  display: inline-block;
  background: #000000c9;
  color: #000;
  padding: 12px 24px;
  text-align: center;
  text-decoration: none;
  font-size: 16px;
  cursor: pointer;
a:hover {
  cursor: pointer;
  transition: 0.3s ease-in;

Link tag

<a href="#">Hover me<a>

How do I create a pause/wait function using Qt?

@kshark27's answer didn't work for me for some reason (because I use Qt 5.7?) so I ended up doing this:

while (someCondition) {

   // do something

   QThread::sleep(1); // 1 second


If this is done in the GUI thread, it obviously introduces a 1 second GUI lag before responding to user events. But if you can live with it, this solution is probably an easiest to implement and even Qt endorses it in their Threading Basics article (see When to Use Alternatives to Threads section).

Including dependencies in a jar with Maven provides an excellent explanation of the alternatives:

There are three common methods for constructing an uber-JAR:

  1. Unshaded. Unpack all JAR files, then repack them into a single JAR.
    • Pro: Works with Java's default class loader.
    • Con: Files present in multiple JAR files with the same path (e.g., META-INF/services/javax.script.ScriptEngineFactory) will overwrite one another, resulting in faulty behavior.
    • Tools: Maven Assembly Plugin, Classworlds Uberjar
  2. Shaded. Same as unshaded, but rename (i.e., "shade") all packages of all dependencies.
    • Pro: Works with Java's default class loader. Avoids some (not all) dependency version clashes.
    • Con: Files present in multiple JAR files with the same path (e.g., META-INF/services/javax.script.ScriptEngineFactory) will overwrite one another, resulting in faulty behavior.
    • Tools: Maven Shade Plugin
  3. JAR of JARs. The final JAR file contains the other JAR files embedded within.
    • Pro: Avoids dependency version clashes. All resource files are preserved.
    • Con: Needs to bundle a special "bootstrap" classloader to enable Java to load classes from the wrapped JAR files. Debugging class loader issues becomes more complex.
    • Tools: Eclipse JAR File Exporter, One-JAR.

What is the size of a pointer?

They can be different on word-addressable machines (e.g., Cray PVP systems).

Most computers today are byte-addressable machines, where each address refers to a byte of memory. There, all data pointers are usually the same size, namely the size of a machine address.

On word-adressable machines, each machine address refers instead to a word larger than a byte. On these, a (char *) or (void *) pointer to a byte of memory has to contain both a word address plus a byte offset within the addresed word.

How to copy files across computers using SSH and MAC OS X Terminal

You can do this with the scp command, which uses the ssh protocol to copy files across machines. It extends the syntax of cp to allow references to other systems:

scp username1@hostname1:/path/to/file username2@hostname2:/path/to/other/file

Copy something from this machine to some other machine:

scp /path/to/local/file username@hostname:/path/to/remote/file

Copy something from another machine to this machine:

scp username@hostname:/path/to/remote/file /path/to/local/file

Copy with a port number specified:

scp -P 1234 username@hostname:/path/to/remote/file /path/to/local/file

How can I run dos2unix on an entire directory?

I have had the same problem and thanks to the posts here I have solved it. I knew that I have around a hundred files and I needed to run it for *.js files only. find . -type f -name '*.js' -print0 | xargs -0 dos2unix

Thank you all for your help.

Creating and returning Observable from Angular 2 Service

In the service.ts file -

a. import 'of' from observable/of
b. create a json list
c. return json object using Observable.of()
Ex. -

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { of } from 'rxjs/observable/of';

export class ClientListService {
    private clientList;

    constructor() {
        this.clientList = [
            {name: 'abc', address: 'Railpar'},
            {name: 'def', address: 'Railpar 2'},
            {name: 'ghi', address: 'Panagarh'},
            {name: 'jkl', address: 'Panagarh 2'},

    getClientList () {
        return Observable.of(this.clientList);

In the component where we are calling the get function of the service -

this.clientListService.getClientList().subscribe(res => this.clientList = res);

T-SQL to list all the user mappings with database roles/permissions for a Login

Is this the kind of thing you want? You might want to extend it to get more info out of the sys tables.

use master

DECLARE @name VARCHAR(50) -- database name 

select name from sys.databases

OPEN db_cursor  
FETCH NEXT FROM db_cursor INTO @name  

       print @name
      exec('USE ' +  @name + '; select, from sys.database_role_members drm
            join sys.database_principals rp on (drm.role_principal_id = rp.principal_id)
            join sys.database_principals mp on (drm.member_principal_id = mp.principal_id)')
       FETCH NEXT FROM db_cursor INTO @name  

CLOSE db_cursor  
DEALLOCATE db_cursor

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

No need to use .each. click already binds to all div occurrences.

$('div').click(function(e) {

See Demo

Note: use hard binding such as .click to make sure dynamically loaded elements don't get bound.

Cannot find either column "dbo" or the user-defined function or aggregate "dbo.Splitfn", or the name is ambiguous

A general answer

select * from [dbo].[SplitString]('1,2',',') -- Will work 


select [dbo].[SplitString]('1,2',',')  -- will not work and throws this error

Jquery - How to get the style display attribute "none / block"

My answer

 * Display form to reply comment
function displayReplyForm(commentId) {
    var replyForm = $('#reply-form-' + commentId);
    if (replyForm.css('display') == 'block') { // Current display
        replyForm.css('display', 'none');
    } else { // Hide reply form
        replyForm.css('display', 'block');

How to get a random value from dictionary?

b = { 'video':0, 'music':23,"picture":12 } 
random.choice(tuple(b.items())) ('music', 23) 
random.choice(tuple(b.items())) ('music', 23) 
random.choice(tuple(b.items())) ('picture', 12) 
random.choice(tuple(b.items())) ('video', 0) 

Error: EACCES: permission denied

First install without -g (global) on root. After try using -g (global) It worked for me.

Instantiating a generic type

You basically have two choices:

1.Require an instance:

public Navigation(T t) {     this("", "", t); } 

2.Require a class instance:

public Navigation(Class<T> c) {     this("", "", c.newInstance()); } 

You could use a factory pattern, but ultimately you'll face this same issue, but just push it elsewhere in the code.

Python mock multiple return values

You can assign an iterable to side_effect, and the mock will return the next value in the sequence each time it is called:

>>> from unittest.mock import Mock
>>> m = Mock()
>>> m.side_effect = ['foo', 'bar', 'baz']
>>> m()
>>> m()
>>> m()

Quoting the Mock() documentation:

If side_effect is an iterable then each call to the mock will return the next value from the iterable.

OnclientClick and OnClick is not working at the same time?

function UpdateClick(btn) {

    for (i = 0; i < Page_Validators.length; i++) {


        if (Page_Validators[i].isvalid == false)

            return false;

    btn.disabled = 'false';

    btn.value = 'Please Wait...';

    return true;

.NET - Get protocol, host, and port

Well if you are doing this in Asp.Net or have access to HttpContext.Current.Request I'd say these are easier and more general ways of getting them:

var scheme = Request.Url.Scheme; // will get http, https, etc.
var host = Request.Url.Host; // will get
var port = Request.Url.Port; // will get the port
var path = Request.Url.AbsolutePath; // should get the /pages/page1.aspx part, can't remember if it only get pages/page1.aspx

I hope this helps. :)

Warning: mysql_connect(): [2002] No such file or directory (trying to connect via unix:///tmp/mysql.sock) in

I got the same errors. Mysql was running as a standalone application before I started phpMyAdmin.

I just stopped mysql Then sudo /Applications/XAMPP/xamppfiles/xampp stop sudo /Applications/XAMPP/xamppfiles/xampp start

It worked fine vs location.hostname and cross-browser compatibility?

host just includes the port number if there is one specified. If there is no port number specifically in the URL, then it returns the same as hostname. You pick whether you care to match the port number or not. See for more info.

I would assume you want hostname to just get the site name.

Date / Timestamp to record when a record was added to the table?

You can create a non-nullable DATETIME column on your table, and create a DEFAULT constraint on it to auto populate when a row is added.


SomeField INTEGER,

What is the easiest way to clear a database from the CLI with in Django?

You can use the Django-Truncate library to delete all data of a table without destroying the table structure.


  1. First, install django-turncate using your terminal/command line:
pip install django-truncate
  1. Add "django_truncate" to your INSTALLED_APPS in the file:
  1. Use this command in your terminal to delete all data of the table from the app.
python truncate --apps app_name --models table_name

How to make Sonar ignore some classes for codeCoverage metric?

I had to struggle for a little bit but I found a solution, I added


and the coverage metric was cancelled from the dashboard at all, so I realized that the problem was the path I was passing, not the property. In my case the path to exclude was java/org/acme/exceptions, so I used :


and it worked, but since I don't have sub-folders it also works with


Is it possible to make an HTML anchor tag not clickable/linkable using CSS?

Yes.. It is possible using css

<a class="disable-me" href="page.html">page link</a>

.disable-me {
    pointer-events: none;

How to npm install to a specified directory?

I am using a powershell build and couldn't get npm to run without changing the current directory.

Ended up using the start command and just specifying the working directory:

start "npm" -ArgumentList "install --warn" -wo $buildFolder

Easier way to debug a Windows service


This approach is by far the easiest:

I leave my original answer below for posterity.

My services tend to have a class that encapsulates a Timer as I want the service to check at regular intervals whether there is any work for it to do.

We new up the class and call StartEventLoop() during the service start-up. (This class could easily be used from a console app too.)

The nice side-effect of this design is that the arguments with which you set up the Timer can be used to have a delay before the service actually starts working, so that you have time to attach a debugger manually.

p.s. How to attach the debugger manually to a running process...?

using System;
using System.Threading;
using System.Configuration;    

public class ServiceEventHandler
    Timer _timer;
    public ServiceEventHandler()
        // get configuration etc.
        _timer = new Timer(
            new TimerCallback(EventTimerCallback)
            , null
            , Timeout.Infinite
            , Timeout.Infinite);

    private void EventTimerCallback(object state)
        // do something

    public void StartEventLoop()
        // wait a minute, then run every 30 minutes
        _timer.Change(TimeSpan.Parse("00:01:00"), TimeSpan.Parse("00:30:00");

Also I used to do the following (already mentioned in previous answers but with the conditional compiler [#if] flags to help avoid it firing in a Release build).

I stopped doing it this way because sometimes we'd forget to build in Release and have a debugger break in an app running on a client demo (embarrasing!).

if (!System.Diagnostics.Debugger.IsAttached)

How to handle change of checkbox using jQuery?

Hope, this would be of some help.

$('input[type=checkbox]').change(function () {
    if ($(this).prop("checked")) {
        //do the stuff that you would do when 'checked'

    //Here do the stuff you want to do when 'unchecked'

Call angularjs function using jquery/javascript

Your plunker is firing off


Before anything is rendered.

You can verify that by wrapping it in a timeout

setTimeout(function() {
}, 1000);

You also need to acutally add an ID to your div.

<div ng-app='MyModule' ng-controller="MyController" id="MyController">

Java: how do I get a class literal from a generic type?

To expound on cletus' answer, at runtime all record of the generic types is removed. Generics are processed only in the compiler and are used to provide additional type safety. They are really just shorthand that allows the compiler to insert typecasts at the appropriate places. For example, previously you'd have to do the following:

List x = new ArrayList();
x.add(new SomeClass());
Iterator i = x.iterator();
SomeClass z = (SomeClass);


List<SomeClass> x = new ArrayList<SomeClass>();
x.add(new SomeClass());
Iterator<SomeClass> i = x.iterator();
SomeClass z =;

This allows the compiler to check your code at compile-time, but at runtime it still looks like the first example.

Facebook API - How do I get a Facebook user's profile image through the Facebook API (without requiring the user to "Allow" the application)

Are you concerned about the profile picture size? at the time of implementing login with Facebook using PHP. We’ll show you the simple way to get large size profile picture in Facebook PHP SDK. Also, you can get the custom size image of Facebook profile.

Set the profile picture dimension by using the following line of code.

$userProfile = $facebook->api('/me?fields=picture.width(400).height(400)');

check this post:

How to make one Observable sequence wait for another to complete before emitting?

A couple ways I can think of

import {take, publish} from 'rxjs/operators'
import {concat} from 'rxjs'

//Method one

var one = someObservable.pipe(take(1));
var two = someOtherObservable.pipe(take(1));
concat(one, two).subscribe(function() {/*do something */});

//Method two, if they need to be separate for some reason
var one = someObservable.pipe(take(1));
var two = someOtherObservable.pipe(take(1), publish());
two.subscribe(function(){/*do something */});
one.subscribe(function(){/*do something */}, null, two.connect.bind(two));

String comparison in bash. [[: not found

I had this problem when installing Heroku Toolbelt

This is how I solved the problem

$ ls -l /bin/sh
lrwxrwxrwx 1 root root 4 ago 15  2012 /bin/sh -> dash

As you can see, /bin/sh is a link to "dash" (not bash), and [[ is bash syntactic sugarness. So I just replaced the link to /bin/bash. Careful using rm like this in your system!

$ sudo rm /bin/sh
$ sudo ln -s /bin/bash /bin/sh

Changing datagridview cell color dynamically

Thanks it working

here i am done with this by qty field is zero means it shown that cells are in red color

        int count = 0;

        foreach (DataGridViewRow row in ItemDg.Rows)
            int qtyEntered = Convert.ToInt16(row.Cells[1].Value);
            if (qtyEntered <= 0)
                ItemDg[0, count].Style.BackColor = Color.Red;//to color the row
                ItemDg[1, count].Style.BackColor = Color.Red;

                ItemDg[0, count].ReadOnly = true;//qty should not be enter for 0 inventory                       
            ItemDg[0, count].Value = "0";//assign a default value to quantity enter


Why do symbols like apostrophes and hyphens get replaced with black diamonds on my website?

Look at your actual html code and check that the weird symbols are not originating there. This issue came up when I started coding in Notepad++ halfway after coding in Notepad. It seems to me that the older version of Notepad I was using may have used different encoding to Notepad's++ UTF-8 encoding. After I transferred my code from Notepad to Notepad++, the apostrophes got replaced with weird symbols, so I simply had to remove the symbols from my Notepad++ code.

Is there a way to make HTML5 video fullscreen?

HTML 5 video does go fullscreen in the latest nightly build of Safari, though I'm not sure how it is technically accomplished.

How to compute the similarity between two text documents?

To find sentence similarity with very less dataset and to get high accuracy you can use below python package which is using pre-trained BERT models,

pip install similar-sentences

Print Pdf in C#

It is possible to use Ghostscript to read PDF files and print them to a named printer.

Apply CSS to jQuery Dialog Buttons

If still noting is working for you add the following styles on your page style sheet

.ui-widget-content .ui-state-default {
  border: 0px solid #d3d3d3;
  background: #00ACD6 50% 50% repeat-x;
  font-weight: normal;
  color: #fff;

It will change the background color of the dialog buttons.

How to Count Duplicates in List with LINQ

You can use "group by" + "orderby". See LINQ 101 for details

var list = new List<string> {"a", "b", "a", "c", "a", "b"};
var q = from x in list
        group x by x into g
        let count = g.Count()
        orderby count descending
        select new {Value = g.Key, Count = count};
foreach (var x in q)
    Console.WriteLine("Value: " + x.Value + " Count: " + x.Count);

In response to this post (now deleted):

If you have a list of some custom objects then you need to use custom comparer or group by specific property.

Also query can't display result. Show us complete code to get a better help.

Based on your latest update:

You have this line of code:

group xx by xx into g

Since xx is a custom object system doesn't know how to compare one item against another. As I already wrote, you need to guide compiler and provide some property that will be used in objects comparison or provide custom comparer. Here is an example:

Note that I use Foo.Name as a key - i.e. objects will be grouped based on value of Name property.

There is one catch - you treat 2 objects to be duplicate based on their names, but what about Id ? In my example I just take Id of the first object in a group. If your objects have different Ids it can be a problem.

//Using extension methods
var q = list.GroupBy(x => x.Name)
            .Select(x => new {Count = x.Count(), 
                              Name = x.Key, 
                              ID = x.First().ID})
            .OrderByDescending(x => x.Count);

//Using LINQ
var q = from x in list
        group x by x.Name into g
        let count = g.Count()
        orderby count descending
        select new {Name = g.Key, Count = count, ID = g.First().ID};

foreach (var x in q)
    Console.WriteLine("Count: " + x.Count + " Name: " + x.Name + " ID: " + x.ID);

npm install -g less does not work: EACCES: permission denied

sudo chown -R $USER /usr/local/lib/node_modules This command will work

How to remove elements/nodes from angular.js array

For anyone returning to this question. The correct "Angular Way" to remove items from an array is with $filter. Just inject $filter into your controller and do the following:

$scope.items = $filter('filter')($scope.items, {name: '!ted'})

You don't need to load any additional libraries or resort to Javascript primitives.

Angular2: child component access parent class variable/function

What about a little trickery like NgModel does with NgForm? You have to register your parent as a provider, then load your parent in the constructor of the child.

That way, you don't have to put [sharedList] on all your children.

// Parent.ts
export var parentProvider = {
    provide: Parent,
    useExisting: forwardRef(function () { return Parent; })

    selector: 'parent',
    template: '<div><ng-content></ng-content></div>',
    providers: [parentProvider]
export class Parent {
    public sharedList = [];

// Child.ts
    selector: 'child',
    template: '<div>child</div>'
export class Child {
    constructor(private parent: Parent) {

Then your HTML

<parent [sharedList]="myArray">

You can find more information on the subject in the Angular documentation:

Linq to Sql: Multiple left outer joins

I figured out how to use multiple left outer joins in VB.NET using LINQ to SQL:

Dim db As New ContractDataContext()

Dim query = From o In db.Orders _
            Group Join v In db.Vendors _
            On v.VendorNumber Equals o.VendorNumber _
            Into ov = Group _
            From x In ov.DefaultIfEmpty() _
            Group Join s In db.Status _
            On s.Id Equals o.StatusId Into os = Group _
            From y In os.DefaultIfEmpty() _
            Where o.OrderNumber >= 100000 And o.OrderNumber <= 200000 _
            Select Vendor_Name = x.Name, _
                   Order_Number = o.OrderNumber, _
                   Status_Name = y.StatusName

How to add items into a numpy array

One way to do it (may not be the best) is to create another array with the new elements and do column_stack. i.e.

>>>a = array([[1,3,4],[1,2,3]...[1,2,1]])
[[1 3 4]
 [1 2 3]
 [1 2 1]]

>>>b = array([1,2,3])
array([[1, 3, 4, 1],
       [1, 2, 3, 2],
       [1, 2, 1, 3]])

How to maintain a Unique List in Java?

I do not know how efficient this is, However worked for me in a simple context.

List<int> uniqueNumbers = new ArrayList<>();

   public void AddNumberToList(int num)
        if(!uniqueNumbers .contains(num)) {
            uniqueNumbers .add(num);

How can I reverse the order of lines in a file?

at the end of your command put: | tac

tac does exactly what you're asking for, it "Write each FILE to standard output, last line first."

tac is the opposite of cat :-).

Finding the layers and layer sizes for each Docker image

They have a very good answer here:

Just run below images:

docker run --rm -v /var/run/docker.sock:/var/run/docker.sock nate/dockviz images -t

Python: Find index of minimum item in list of floats

Use of the argmin method for numpy arrays.

import numpy as np

However, it is not the fastest method: it is 3 times slower than OP's answer on my computer. It may be the most concise one though.

Postman addon's like in firefox

The feature that I'm missing a lot from postman in Firefox extensions is WebView
(preview when API returns HTML).

Now I'm settled with Fiddler (Inspectors > WebView)

Use CSS to automatically add 'required field' asterisk to form inputs

You can achieve the desired result by encapsulating the HTML code in a div tag which contains the "required' class followed by the "form-group" class. *however this works only if you have Bootstrap.

<div class="form-group required">
    <div class="required">
        <input type="text">

Number of rows affected by an UPDATE in PL/SQL

For those who want the results from a plain command, the solution could be:

  DBMS_OUTPUT.PUT_LINE(TO_Char(SQL%ROWCOUNT)||' rows affected.');

The basic problem is that SQL%ROWCOUNT is a PL/SQL variable (or function), and cannot be directly accessed from an SQL command. By using a noname PL/SQL block, this can be achieved.

... If anyone has a solution to use it in a SELECT Command, I would be interested.

Removing rounded corners from a <select> element in Chrome/Webkit

This works for me (styles the first appearance not the dropdown list):

select {
  -webkit-appearance: none;
  -webkit-border-radius: 0px;

css3 transition animation on load?

Not really, as CSS is applied as soon as possible, but the elements might not be drawn yet. You could guess a delay of 1 or 2 seconds, but this won't look right for most people, depending on the speed of their internet.

In addition, if you want to fade something in for instance, it would require CSS that hides the content to be delivered. If the user doesn't have CSS3 transitions then they would never see it.

I'd recommend using jQuery (for ease of use + you may wish to add animation for other UAs) and some JS like this:

$(document).ready(function() {
        .css({"opacity":0})   // Set to 0 as soon as possible – may result in flicker, but it's not hidden for users with no JS (Googlebot for instance!)
        .delay(200)           // Wait for a bit so the user notices it fade in
        .css({"opacity":1});  // Fade it back in. Swap css for animate in legacy browsers if required.

Along with the transitions added in the CSS. This has the advantage of easily allowing the use of animate instead of the second CSS in legacy browsers if required.

org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]]A child container failed during start

Go to the task manager, kill the java processes and turn the server back on. should work fine.

For homebrew mysql installs, where's my.cnf?

Server version: 8.0.19 Homebrew. macOS Catalina 10.15.5 and installed MySQL via Homebrew. Found this file here:


This solution helped :)

Java - Check if JTextField is empty or not

use the following code :


Interview Question: Merge two sorted singly linked lists without creating new nodes

Simple code in javascript to merge two linked list inplace.

function mergeLists(l1, l2) {
    let head = new ListNode(0); //dummy
    let curr = head;
    while(l1 && l2) {
        if(l2.val >= l1.val) {
   = l1;
            l1 =;
        } else {
   = l2;
        curr =;

Android Animation Alpha

Try this

AlphaAnimation animation1 = new AlphaAnimation(0.2f, 1.0f);

How to Deserialize XML document

How about you just save the xml to a file, and use xsd to generate C# classes?

  1. Write the file to disk (I named it foo.xml)
  2. Generate the xsd: xsd foo.xml
  3. Generate the C#: xsd foo.xsd /classes

Et voila - and C# code file that should be able to read the data via XmlSerializer:

    XmlSerializer ser = new XmlSerializer(typeof(Cars));
    Cars cars;
    using (XmlReader reader = XmlReader.Create(path))
        cars = (Cars) ser.Deserialize(reader);

(include the generated foo.cs in the project)

Requery a subform from another form?

I tried several solutions above, but none solved my problem. Solution to refresh a subform in a form after saving data to database:


It worked fine for me. Good luck.

Call Activity method from adapter

You can do it this way:

Declare interface:

public interface MyInterface{
    public void foo();

Let your Activity imlement it:

    public class MyActivity extends Activity implements MyInterface{
        public void foo(){
            //do stuff
        public onCreate(){
            //your code
            MyAdapter adapter = new MyAdapter(this); //this will work as your 
                                                     //MyInterface listener

Then pass your activity to ListAdater:

public MyAdapter extends BaseAdater{
    private MyInterface listener;

    public MyAdapter(MyInterface listener){
        this.listener = listener;

And somewhere in adapter, when you need to call that Activity method:;

Onclick on bootstrap button

Seem no solutions fix the problem:

$(".anima-area").on('click', function (e) {
            return false; //return true;
$(".anima-area").on('click', function (e) {
 $(".anima-area").click(function (r) {
$(".anima-area").click(function () {
           return false; //return true;

Bootstrap button always maintain th pressed status and block all .click code. If i remove .click function button comeback to work good.

How to make jQuery UI nav menu horizontal?

I just been for 3 days looking for a jquery UI and CSS solution, I merge some code I saw, fix a little, and finally (along the other codes) I could make it work!

<ul id="nav" class="testnav">
    <li><a class="clk" href="#">Item 1</a></li>
    <li><a class="clk" href="#">Item 2</a></li>
    <li><a class="clk" href="#">Item 3</a>
        <ul class="sub-menu">
            <li><a href="#">Item 3-1</a>
                <ul class="sub-menu">
                    <li><a href="#">Item 3-11</a></li>
                    <li><a href="#">Item 3-12</a>
                            <li><a href="#">Item 3-111</a></li>                         
                            <li><a href="#">Item 3-112</a>
                                    <li><a href="#">Item 3-1111</a></li>                            
                                    <li><a href="#">Item 3-1112</a></li>                            
                                    <li><a href="#">Item 3-1113</a>
                                            <li><a href="#">Item 3-11131</a></li>                           
                                            <li><a href="#">Item 3-11132</a></li>                           
                            <li><a href="#">Item 3-113</a></li>
                    <li><a href="#">Item 3-13</a></li>
            <li><a href="#">Item 3-2</a>
                    <li><a href="#."> Item 3-21 </a></li>
                    <li><a href="#."> Item 3-22 </a></li>
                    <li><a href="#."> Item 3-23 </a></li>
            <li><a href="#">Item 3-3</a></li>
            <li><a href="#">Item 3-4</a></li>
            <li><a href="#">Item 3-5</a></li>
    <li><a class="clk" href="#">Item 4</a>
        <ul class="sub-menu">
            <li><a href="#">Item 4-1</a>
                <ul class="sub-menu">
                    <li><a href="#."> Item 4-11 </a></li>
                    <li><a href="#."> Item 4-12 </a></li>
                    <li><a href="#."> Item 4-13 </a>
                            <li><a href="#."> Item 4-131 </a></li>
                            <li><a href="#."> Item 4-132 </a></li>
                            <li><a href="#."> Item 4-133 </a></li>
            <li><a href="#">Item 4-2</a></li>
            <li><a href="#">Item 4-3</a></li>
    <li><a class="clk" href="#">Item 5</a></li>



var menu = "#nav";
var position = {my: "left top", at: "left bottom"};


    position: position,
    blur: function() {
        $(this).menu("option", "position", position);
    focus: function(e, ui) {

        if ($(menu).get(0) !== $(ui).get(0).item.parent().get(0)) {
            $(this).menu("option", "position", {my: "left top", at: "right top"});
});     });


.ui-menu {width: auto;}.ui-menu:after {content: ".";display: block;clear: both;visibility: hidden;line-height: 0;height: 0;}.ui-menu .ui-menu-item {display: inline-block;margin: 0;padding: 0;width: auto;}#nav{text-align: center;font-size: 12px;}#nav li {display: inline-block;}#nav li a span.ui-icon-carat-1-e {float:right;position:static;margin-top:2px;width:16px;height:16px;background:url( no-repeat -64px -16px;}#nav li ul li {width: 120px;border-bottom: 1px solid #ccc;}#nav li ul {width: 120px; }.ui-menu .ui-menu-item li a span.ui-icon-carat-1-e {background:url( no-repeat -32px -16px !important;

jquery change button color onclick

Add this code to your page:

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

AngularJS format JSON string output

You can use an optional parameter of JSON.stringify()

JSON.stringify(value[, replacer [, space]])


  • value The value to convert to a JSON string.
  • replacer If a function, transforms values and properties encountered while stringifying; if an array, specifies the set of properties included in objects in the final string. A detailed description of the replacer function is provided in the javaScript guide article Using native JSON.
  • space Causes the resulting string to be pretty-printed.

For example:

JSON.stringify({a:1,b:2,c:{d:3, e:4}},null,"    ")

will give you following result:

    "a": 1,
    "b": 2,
    "c": {
        "d": 3,
        "e": 4

What's is the difference between include and extend in use case diagram?

This may be contentious but the “includes are always and extends are sometimes” is a very common misconception which has almost taken over now as the de-facto meaning. Here’s a correct approach (in my view, and checked against Jacobson, Fowler, Larmen and 10 other references).

Relationships are dependencies

The key to Include and extend use case relationships is to realize that, common with the rest of UML, the dotted arrow between use cases is a dependency relationship. I’ll use the terms ‘base’, ‘included’ and ‘extending’ to refer to the use case roles.


A base use case is dependent on the included use case(s); without it/them the base use case is incomplete as the included use case(s) represent sub-sequences of the interaction that may happen always OR sometimes. (This is contrary to a popular misconception about this, what your use case suggests always happens in the main scenario and sometimes happens in alternate flows simply depends on what you choose as your main scenario; use cases can easily be restructured to represent a different flow as the main scenario and this should not matter).

In the best practice of one way dependency the base use case knows about (and refers to) the included use case, but the included use case shouldn’t ‘know’ about the base use case. This is why included use cases can be: a) base use cases in their own right and b) shared by a number of base use cases.


The extending use case is dependent on the base use case; it literally extends the behavior described by the base use case. The base use case should be a fully functional use case in its own right (‘include’s included of course) without the extending use case’s additional functionality.

Extending use cases can be used in several situations:

  1. The base use case represents the “must have” functionality of a project while the extending use case represents optional (should/could/want) behavior. This is where the term optional is relevant – optional whether to build/deliver rather than optional whether it sometimes runs as part of the base use case sequence.
  2. In phase 1 you can deliver the base use case which meets the requirements at that point, and phase 2 will add additional functionality described by the extending use case. This can contain sequences that are always or sometimes performed after phase 2 is delivered (again contrary to popular misconception).
  3. It can be used to extract out subsequences of the base use case, especially when they represent ‘exceptional’ complex behavior with its own alternative flows.

One important aspect to consider is that the extending use case can ‘insert’ behavior in several places in the base use case’s flow, not just in a single place as an included use case does. For this reason, it is highly unlikely that an extending use case will be suitable to extend more than one base use case.

As to dependency, the extending use case is dependent on the base use case and is again a one-way dependency, i.e. the base use case doesn’t need any reference to the extending use case in the sequence. That doesn’t mean you can’t demonstrate the extension points or add a x-ref to the extending use case elsewhere in the template, but the base use case must be able to work without the extending use case.


I hope I’ve shown that the common misconception of “includes are always, extends are sometimes” is either wrong or at best simplistic. This version actually makes more sense if you consider all the issues about the directionality of the arrows the misconception presents – in the correct model it’s just dependency and doesn’t potentially change if you refactor the use case contents.

How to check whether a pandas DataFrame is empty?

I use the len function. It's much faster than empty. len(df.index) is even faster.

import pandas as pd
import numpy as np

df = pd.DataFrame(np.random.randn(10000, 4), columns=list('ABCD'))

def empty(df):
    return df.empty

def lenz(df):
    return len(df) == 0

def lenzi(df):
    return len(df.index) == 0

%timeit empty(df)
%timeit lenz(df)
%timeit lenzi(df)

10000 loops, best of 3: 13.9 µs per loop
100000 loops, best of 3: 2.34 µs per loop
1000000 loops, best of 3: 695 ns per loop

len on index seems to be faster

Easiest way to pass an AngularJS scope variable from directive to controller?

Wait until angular has evaluated the variable

I had a lot of fiddling around with this, and couldn't get it to work even with the variable defined with "=" in the scope. Here's three solutions depending on your situation.

Solution #1

I found that the variable was not evaluated by angular yet when it was passed to the directive. This means that you can access it and use it in the template, but not inside the link or app controller function unless we wait for it to be evaluated.

If your variable is changing, or is fetched through a request, you should use $observe or $watch:

app.directive('yourDirective', function () {
    return {
        restrict: 'A',
        // NB: no isolated scope!!
        link: function (scope, element, attrs) {
            // observe changes in attribute - could also be scope.$watch
            attrs.$observe('yourDirective', function (value) {
                if (value) {
                    // pass value to app controller
                    scope.variable = value;
        // the variable is available in directive controller,
        // and can be fetched as done in link function
        controller: ['$scope', '$element', '$attrs',
            function ($scope, $element, $attrs) {
                // observe changes in attribute - could also be scope.$watch
                $attrs.$observe('yourDirective', function (value) {
                    if (value) {
                        // pass value to app controller
                        $scope.variable = value;
.controller('MyCtrl', ['$scope', function ($scope) {
    // variable passed to app controller
    $scope.$watch('variable', function (value) {
        if (value) {

And here's the html (remember the brackets!):

<div ng-controller="MyCtrl">
    <div your-directive="{{ someObject.someVariable }}"></div>
    <!-- use ng-bind in stead of {{ }}, when you can to avoids FOUC -->
    <div ng-bind="variable"></div>

Note that you should not set the variable to "=" in the scope, if you are using the $observe function. Also, I found that it passes objects as strings, so if you're passing objects use solution #2 or scope.$watch(attrs.yourDirective, fn) (, or #3 if your variable is not changing).

Solution #2

If your variable is created in e.g. another controller, but just need to wait until angular has evaluated it before sending it to the app controller, we can use $timeout to wait until the $apply has run. Also we need to use $emit to send it to the parent scope app controller (due to the isolated scope in the directive):

app.directive('yourDirective', ['$timeout', function ($timeout) {
    return {
        restrict: 'A',
        // NB: isolated scope!!
        scope: {
            yourDirective: '='
        link: function (scope, element, attrs) {
            // wait until after $apply
                // use scope.$emit to pass it to controller
                scope.$emit('notification', scope.yourDirective);
        // the variable is available in directive controller,
        // and can be fetched as done in link function
        controller: [ '$scope', function ($scope) {
            // wait until after $apply
                // use $scope.$emit to pass it to controller
                $scope.$emit('notification', scope.yourDirective);
.controller('MyCtrl', ['$scope', function ($scope) {
    // variable passed to app controller
    $scope.$on('notification', function (evt, value) {
        $scope.variable = value;

And here's the html (no brackets!):

<div ng-controller="MyCtrl">
    <div your-directive="someObject.someVariable"></div>
    <!-- use ng-bind in stead of {{ }}, when you can to avoids FOUC -->
    <div ng-bind="variable"></div>

Solution #3

If your variable is not changing and you need to evaluate it in your directive, you can use the $eval function:

app.directive('yourDirective', function () {
    return {
        restrict: 'A',
        // NB: no isolated scope!!
        link: function (scope, element, attrs) {
            // executes the expression on the current scope returning the result
            // and adds it to the scope
            scope.variable = scope.$eval(attrs.yourDirective);

        // the variable is available in directive controller,
        // and can be fetched as done in link function
        controller: ['$scope', '$element', '$attrs',
            function ($scope, $element, $attrs) {
                // executes the expression on the current scope returning the result
                // and adds it to the scope
                scope.variable = scope.$eval($attrs.yourDirective);
.controller('MyCtrl', ['$scope', function ($scope) {
    // variable passed to app controller
    $scope.$watch('variable', function (value) {
        if (value) {

And here's the html (remember the brackets!):

<div ng-controller="MyCtrl">
    <div your-directive="{{ someObject.someVariable }}"></div>
    <!-- use ng-bind instead of {{ }}, when you can to avoids FOUC -->
    <div ng-bind="variable"></div>

Also, have a look at this answer:

Reference for FOUC (flash of unstyled content) issue:

For the interested: here's an article on the angular life cycle

How to set up gradle and android studio to do release build?

To compile with release build as shown below:

enter image description here

Cannot create a connection to data source Error (rsErrorOpeningConnection) in SSRS

The issue is because your data source is not setup properly, to do that please verify your data source connection, in order to do that first navigate to Report Service Configuration Manager through

clicking on the start -> Start All -> Microsoft SQL Server ->Configuration Tool -> “Report Service Configuration Manager”

The open Report Manager URL and then navigate to the Data Source folder, see in the picture below

Then Create a Data Source or configure the one that is already there by right click on your database source and select "Manage" as is shown below

Now on the properties tab, on your left menu, fill out the data source with your connection string and username and password, after that click on test connection, and if the connection was successful, then click "Apply"

Navigate to the folder that contains your report in this case "SurveyLevelReport"

And Finally set your Report to the Data Source that you set up previously, and click Apply

Create a new line in Java's FileWriter

One can use PrintWriter to wrap the FileWriter, as it has many additional useful methods.

try(PrintWriter pw = new PrintWriter(new FileWriter(new File("file.txt"), false))){
   pw.println();//new line
   pw.print("text");//print without new line
   pw.println(10);//print with new line
   pw.printf("%2.f", 0.567);//print double to 2 decimal places (without new line)

How do I revert all local changes in Git managed project to previous state?

I searched for a similar issue,

Wanted to throw away local commits:

  1. cloned the repository (git clone)
  2. switched to dev branch (git checkout dev)
  3. did few commits (git commit -m "commit 1")
  4. but decided to throw away these local commits to go back to remote (origin/dev)

So did the below:

git reset --hard origin/dev


git status  

        On branch dev  
        Your branch is up-to-date with 'origin/dev'.  
        nothing to commit, working tree clean  

now local commits are lost, back to the initial cloned state, point 1 above.

How to remove text from a string?


This will replace all the occurrences of that specific string from original string.

Java AES encryption and decryption

Here is the implementation that was mentioned above:

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.StringUtils;

    String passEncrypt = "my password";
    byte[] saltEncrypt = "choose a better salt".getBytes();
    int iterationsEncrypt = 10000;
    SecretKeyFactory factoryKeyEncrypt = SecretKeyFactory
    SecretKey tmp = factoryKeyEncrypt.generateSecret(new PBEKeySpec(
            passEncrypt.toCharArray(), saltEncrypt, iterationsEncrypt,
    SecretKeySpec encryptKey = new SecretKeySpec(tmp.getEncoded(),

    Cipher aesCipherEncrypt = Cipher
    aesCipherEncrypt.init(Cipher.ENCRYPT_MODE, encryptKey);

    // get the bytes
    byte[] bytes = StringUtils.getBytesUtf8(toEncodeEncryptString);

    // encrypt the bytes
    byte[] encryptBytes = aesCipherEncrypt.doFinal(bytes);

    // encode 64 the encrypted bytes
    String encoded = Base64.encodeBase64URLSafeString(encryptBytes);

    System.out.println("e: " + encoded);

    // assume some transport happens here

    // create a new string, to make sure we are not pointing to the same
    // string as the one above
    String encodedEncrypted = new String(encoded);

    //we recreate the same salt/encrypt as if its a separate system
    String passDecrypt = "my password";
    byte[] saltDecrypt = "choose a better salt".getBytes();
    int iterationsDecrypt = 10000;
    SecretKeyFactory factoryKeyDecrypt = SecretKeyFactory
    SecretKey tmp2 = factoryKeyDecrypt.generateSecret(new PBEKeySpec(passDecrypt
            .toCharArray(), saltDecrypt, iterationsDecrypt, 128));
    SecretKeySpec decryptKey = new SecretKeySpec(tmp2.getEncoded(), "AES");

    Cipher aesCipherDecrypt = Cipher.getInstance("AES/ECB/PKCS5Padding");
            aesCipherDecrypt.init(Cipher.DECRYPT_MODE, decryptKey);

    //basically we reverse the process we did earlier

    // get the bytes from encodedEncrypted string
    byte[] e64bytes = StringUtils.getBytesUtf8(encodedEncrypted);

    // decode 64, now the bytes should be encrypted
    byte[] eBytes = Base64.decodeBase64(e64bytes);

    // decrypt the bytes
    byte[] cipherDecode = aesCipherDecrypt.doFinal(eBytes);

    // to string
    String decoded = StringUtils.newStringUtf8(cipherDecode);

    System.out.println("d: " + decoded);

catch (Exception e)

how to get the value of a textarea in jquery?

You need to use .val() for textarea as it is an element and not a wrapper. Try


Updated fiddle

XML Carriage return encoding

To insert a CR into XML, you need to use its character entity &#13;.

This is because compliant XML parsers must, before parsing, translate CRLF and any CR not followed by a LF to a single LF. This behavior is defined in the End-of-Line handling section of the XML 1.0 specification.

MassAssignmentException in Laravel

I used this and have no problem:

protected $guarded=[];

How does String.Index work in Swift

enter image description here

All of the following examples use

var str = "Hello, playground"

startIndex and endIndex

  • startIndex is the index of the first character
  • endIndex is the index after the last character.


// character
str[str.startIndex] // H
str[str.endIndex]   // error: after last character

// range
let range = str.startIndex..<str.endIndex
str[range]  // "Hello, playground"

With Swift 4's one-sided ranges, the range can be simplified to one of the following forms.

let range = str.startIndex...
let range = ..<str.endIndex

I will use the full form in the follow examples for the sake of clarity, but for the sake of readability, you will probably want to use the one-sided ranges in your code.


As in: index(after: String.Index)

  • after refers to the index of the character directly after the given index.


// character
let index = str.index(after: str.startIndex)
str[index]  // "e"

// range
let range = str.index(after: str.startIndex)..<str.endIndex
str[range]  // "ello, playground"


As in: index(before: String.Index)

  • before refers to the index of the character directly before the given index.


// character
let index = str.index(before: str.endIndex)
str[index]  // d

// range
let range = str.startIndex..<str.index(before: str.endIndex)
str[range]  // Hello, playgroun


As in: index(String.Index, offsetBy: String.IndexDistance)

  • The offsetBy value can be positive or negative and starts from the given index. Although it is of the type String.IndexDistance, you can give it an Int.


// character
let index = str.index(str.startIndex, offsetBy: 7)
str[index]  // p

// range
let start = str.index(str.startIndex, offsetBy: 7)
let end = str.index(str.endIndex, offsetBy: -6)
let range = start..<end
str[range]  // play


As in: index(String.Index, offsetBy: String.IndexDistance, limitedBy: String.Index)

  • The limitedBy is useful for making sure that the offset does not cause the index to go out of bounds. It is a bounding index. Since it is possible for the offset to exceed the limit, this method returns an Optional. It returns nil if the index is out of bounds.


// character
if let index = str.index(str.startIndex, offsetBy: 7, limitedBy: str.endIndex) {
    str[index]  // p

If the offset had been 77 instead of 7, then the if statement would have been skipped.

Why is String.Index needed?

It would be much easier to use an Int index for Strings. The reason that you have to create a new String.Index for every String is that Characters in Swift are not all the same length under the hood. A single Swift Character might be composed of one, two, or even more Unicode code points. Thus each unique String must calculate the indexes of its Characters.

It is possibly to hide this complexity behind an Int index extension, but I am reluctant to do so. It is good to be reminded of what is actually happening.

VIM Disable Automatic Newline At End Of File

OK, you being on Windows complicates things ;)

As the 'binary' option resets the 'fileformat' option (and writing with 'binary' set always writes with unix line endings), let's take out the big hammer and do it externally!

How about defining an autocommand (:help autocommand) for the BufWritePost event? This autocommand is executed after every time you write a whole buffer. In this autocommand call a small external tool (php, perl or whatever script) that strips off the last newline of the just written file.

So this would look something like this and would go into your .vimrc file:

autocmd!   "Remove all autocmds (for current group), see below"
autocmd BufWritePost *.php !your-script <afile>

Be sure to read the whole vim documentation about autocommands if this is your first time dealing with autocommands. There are some caveats, e.g. it's recommended to remove all autocmds in your .vimrc in case your .vimrc might get sourced multiple times.

Is it possible to specify a different ssh port when using rsync?

The correct syntax is to tell Rsync to use a custom SSH command (adding -p 2222), which creates a secure tunnel to remote side using SSH, then connects via localhost:873

rsync -rvz --progress --remove-sent-files -e "ssh -p 2222" ./dir user@host/path

Rsync runs as a daemon on TCP port 873, which is not secure.

From Rsync man:

Push: rsync [OPTION...] SRC... [USER@]HOST:DEST

Which misleads people to try this:

rsync -rvz --progress --remove-sent-files ./dir user@host:2222/path

However, that is instructing it to connect to Rsync daemon on port 2222, which is not there.

Concatenate chars to form String in java

Use str = ""+a+b+c;

Here the first + is String concat, so the result will be a String. Note where the "" lies is important.

Or (maybe) better, use a StringBuilder.

Class vs. static method in JavaScript

In additions, now it is possible to do with class and static

'use strict'

class Foo {
 static talk() {

 speak() {


will give

var a = new Foo();;  // 'talk';    // err 'is not a function'
a.speak();   // 'speak'
Foo.speak(); // err 'is not a function'

What are the differences between "=" and "<-" assignment operators in R?

What are the differences between the assignment operators = and <- in R?

As your example shows, = and <- have slightly different operator precedence (which determines the order of evaluation when they are mixed in the same expression). In fact, ?Syntax in R gives the following operator precedence table, from highest to lowest:

‘-> ->>’           rightwards assignment
‘<- <<-’           assignment (right to left)
‘=’                assignment (right to left)

But is this the only difference?

Since you were asking about the assignment operators: yes, that is the only difference. However, you would be forgiven for believing otherwise. Even the R documentation of ?assignOps claims that there are more differences:

The operator <- can be used anywhere, whereas the operator = is only allowed at the top level (e.g., in the complete expression typed at the command prompt) or as one of the subexpressions in a braced list of expressions.

Let’s not put too fine a point on it: the R documentation is wrong. This is easy to show: we just need to find a counter-example of the = operator that isn’t (a) at the top level, nor (b) a subexpression in a braced list of expressions (i.e. {…; …}). — Without further ado:

# Error: object 'x' not found
sum((x = 1), 2)
# [1] 3
# [1] 1

Clearly we’ve performed an assignment, using =, outside of contexts (a) and (b). So, why has the documentation of a core R language feature been wrong for decades?

It’s because in R’s syntax the symbol = has two distinct meanings that get routinely conflated (even by experts, including in the documentation cited above):

  1. The first meaning is as an assignment operator. This is all we’ve talked about so far.
  2. The second meaning isn’t an operator but rather a syntax token that signals named argument passing in a function call. Unlike the = operator it performs no action at runtime, it merely changes the way an expression is parsed.

So how does R decide whether a given usage of = refers to the operator or to named argument passing? Let’s see.

In any piece of code of the general form …

‹function_name›(‹argname› = ‹value›, …)
‹function_name›(‹args›, ‹argname› = ‹value›, …)

… the = is the token that defines named argument passing: it is not the assignment operator. Furthermore, = is entirely forbidden in some syntactic contexts:

if (‹var› = ‹value›) …
while (‹var› = ‹value›) …
for (‹var› = ‹value› in ‹value2›) …
for (‹var1› in ‹var2› = ‹value›) …

Any of these will raise an error “unexpected '=' in ‹bla›”.

In any other context, = refers to the assignment operator call. In particular, merely putting parentheses around the subexpression makes any of the above (a) valid, and (b) an assignment. For instance, the following performs assignment:

median((x = 1 : 10))

But also:

if (! (nf = length(from))) return()

Now you might object that such code is atrocious (and you may be right). But I took this code from the base::file.copy function (replacing <- with =) — it’s a pervasive pattern in much of the core R codebase.

The original explanation by John Chambers, which the the R documentation is probably based on, actually explains this correctly:

[= assignment is] allowed in only two places in the grammar: at the top level (as a complete program or user-typed expression); and when isolated from surrounding logical structure, by braces or an extra pair of parentheses.

In sum, by default the operators <- and = do the same thing. But either of them can be overridden separately to change its behaviour. By contrast, <- and -> (left-to-right assignment), though syntactically distinct, always call the same function. Overriding one also overrides the other. Knowing this is rarely practical but it can be used for some fun shenanigans.

Can not deserialize instance of java.lang.String out of START_ARRAY token

The error is:

Can not deserialize instance of java.lang.String out of START_ARRAY token at [Source: line: 1, column: 1095] (through reference chain: JsonGen["platforms"])

In JSON, platforms look like this:

"platforms": [
        "platform": "iphone"
        "platform": "ipad"
        "platform": "android_phone"
        "platform": "android_tablet"

So try change your pojo to something like this:

private List platforms;

public List getPlatforms(){
    return this.platforms;

public void setPlatforms(List platforms){
    this.platforms = platforms;

EDIT: you will need change mobile_networks too. Will look like this:

private List mobile_networks;

public List getMobile_networks() {
    return mobile_networks;

public void setMobile_networks(List mobile_networks) {
    this.mobile_networks = mobile_networks;

Make install, but not to default directories?

It could be dependent upon what is supported by the module you are trying to compile. If your makefile is generated by using autotools, use:


when running the ./configure

some packages allow you to also override when running:

make prefix=<myinstalldir>

however, if your not using ./configure, only way to know for sure is to open up the makefile and check. It should be one of the first few variables at the top.

Docker command can't connect to Docker daemon

Had the same issue and what worked for me was:
Checking the ownership of /var/run/docker.sock

ls -l /var/run/docker.sock

If you're not the owner then change ownership with the command

sudo chown *your-username* /var/run/docker.sock

Then you can go ahead and try executing the docker commands hassle-free :D

PHP Warning: Division by zero

If it shows an error on the first run only, it's probably because you haven't sent any POST data. You should check for POST variables before working with them. Undefined, null, empty array, empty string, etc. are all considered false; and when PHP auto-casts that false boolean value to an integer or a float, it becomes zero. That's what happens with your variables, they are not set on the first run, and thus are treated as zeroes.

10 / $unsetVariable


10 / 0

Bottom line: check if your inputs exist and if they are valid before doing anything with them, also enable error reporting when you're doing local work as it will save you a lot of time. You can enable all errors to be reported like this: error_reporting(E_ALL);

To fix your specific problem: don't do any calculations if there's no input from your form; just show the form instead.

Detect if a page has a vertical scrollbar?

I wrote an updated version of Kees C. Bakker's answer:

const hasVerticalScroll = (node) => {
  if (!node) {
    if (window.innerHeight) {
      return document.body.offsetHeight > window.innerHeight
    return (document.documentElement.scrollHeight > document.documentElement.offsetHeight)
      || (document.body.scrollHeight > document.body.offsetHeight)
  return node.scrollHeight > node.offsetHeight

if (hasVerticalScroll(document.querySelector('body'))) {

The function returns true or false depending whether the page has a vertical scrollbar or not.

For example:

const hasVScroll = hasVerticalScroll(document.querySelector('body'))

if (hasVScroll) {
  console.log('HAS SCROLL', hasVScroll)

jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class

Remove servlet.jar from source web-inf/lib folder as it is available in tomcat lib folder then it works fine

How do I URl encode something in Node.js?

Note that URI encoding is good for the query part, it's not good for the domain. The domain gets encoded using punycode. You need a library like URI.js to convert between a URI and IRI (Internationalized Resource Identifier).

This is correct if you plan on using the string later as a query string:

> encodeURIComponent("http://examplé.org/rosé?rosé=rosé")

If you don't want ASCII characters like /, : and ? to be escaped, use encodeURI instead:

> encodeURI("http://examplé.org/rosé?rosé=rosé")

However, for other use-cases, you might need uri-js instead:

> var URI = require("uri-js");
> URI.serialize(URI.parse("http://examplé.org/rosé?rosé=rosé"))

Ruby Array find_first object?

Guess you just missed the find method in the docs:

my_array.find {|e| e.satisfies_condition? }

Javascript - Get Image height

Try with JQuery:

<script type="text/javascript">
function jquery_get_width_height()
    var imgWidth = $("#img").width();
    var imgHeight = $("#img").height();
    alert("JQuery -- " + "imgWidth: " + imgWidth + " - imgHeight: " + imgHeight);


<script type="text/javascript">
function javascript_get_width_height()
    var img = document.getElementById('img');
    alert("JavaSript -- " + "imgWidth: " + img.width + " - imgHeight: " + img.height);

Run bash command on jenkins pipeline

According to this document, you should be able to do it like so:

node {
    sh "#!/bin/bash \n" + 
       "echo \"Hello from \$SHELL\""

form_for but to post to a different action

new syntax

<%= form_for :user, url: custom_user_path, method: :post do |f|%>

What does it mean to write to stdout in C?

stdout is the standard output file stream. Obviously, it's first and default pointer to output is the screen, however you can point it to a file as desired!

Please read:

C++ is very similar to C however, object oriented.

How to succinctly write a formula with many variables from a data frame?

A slightly different approach is to create your formula from a string. In the formula help page you will find the following example :

## Create a formula for a model with a large number of variables:
xnam <- paste("x", 1:25, sep="")
fmla <- as.formula(paste("y ~ ", paste(xnam, collapse= "+")))

Then if you look at the generated formula, you will get :

R> fmla
y ~ x1 + x2 + x3 + x4 + x5 + x6 + x7 + x8 + x9 + x10 + x11 + 
    x12 + x13 + x14 + x15 + x16 + x17 + x18 + x19 + x20 + x21 + 
    x22 + x23 + x24 + x25

Entity Framework throws exception - Invalid object name 'dbo.BaseCs'

You have to define both the schema and the table in two different places.

the context defines the schema

public class BContext : DbContext
    public BContext(DbContextOptions<BContext> options) : base(options)

    public DbSet<PriorityOverride> PriorityOverrides { get; set; }

    protected override void OnModelCreating(ModelBuilder builder)

        builder.ApplyConfiguration(new OverrideConfiguration());

and for each table

class PriorityOverrideConfiguration : IEntityTypeConfiguration<PriorityOverride>
    public void Configure(EntityTypeBuilder<PriorityOverride> builder)

kubectl apply vs kubectl create?

These are imperative commands :

kubectl run = kubectl create deployment


  • Simple, easy to learn and easy to remember.
  • Require only a single step to make changes to the cluster.


  • Do not integrate with change review processes.
  • Do not provide an audit trail associated with changes.
  • Do not provide a source of records except for what is live.
  • Do not provide a template for creating new objects.

These are imperative object config:

kubectl create -f your-object-config.yaml

kubectl delete -f your-object-config.yaml

kubectl replace -f your-object-config.yaml

Advantages compared to imperative commands:

  • Can be stored in a source control system such as Git.
  • Can integrate with processes such as reviewing changes before push and audit trails.
  • Provides a template for creating new objects.

Disadvantages compared to imperative commands:

  • Requires basic understanding of the object schema.
  • Requires the additional step of writing a YAML file.

Advantages compared to declarative object config:

  • Simpler and easier to understand.
  • More mature after Kubernetes version 1.5.

Disadvantages compared to declarative object configuration:

  • Works best on files, not directories.
  • Updates to live objects must be reflected in configuration files, or they will be lost during the next replacement.

These are declarative object config

kubectl diff -f configs/

kubectl apply -f configs/

Advantages compared to imperative object config:

  • Changes made directly to live objects are retained, even if they are not merged back into the configuration files.
  • Better support for operating on directories and automatically detecting operation types (create, patch, delete) per-object.

Disadvantages compared to imperative object configuration:

  • Harder to debug and understand results when they are unexpected.
  • Partial updates using diffs create complex merge and patch operations.

e.printStackTrace equivalent in python

import traceback

When doing this inside an except ...: block it will automatically use the current exception. See for more information.

Is there a C++ decompiler?

You can use IDA Pro by Hex-Rays. You will usually not get good C++ out of a binary unless you compiled in debugging information. Prepare to spend a lot of manual labor reversing the code.

If you didn't strip the binaries there is some hope as IDA Pro can produce C-alike code for you to work with. Usually it is very rough though, at least when I used it a couple of years ago.

What is the 'realtime' process priority setting for?

It would be the highest available priority setting, and would usually only be used on box that was dedicated to running that specific program. It's actually high enough that it could cause starvation of the keyboard and mouse threads to the extent that they become unresponsive.

So basicly, if you have to ask, don't use it :)

Getting reference to the top-most view/window in iOS application

Whenever I want to display some overlay on top of everything else, I just add it on top of the Application Window directly:

[[[UIApplication sharedApplication] keyWindow] addSubview:someView]

Google Maps: Auto close open InfoWindows?

How about -

google.maps.event.addListener(yourMarker, 'mouseover', function () {, yourMarker);


google.maps.event.addListener(yourMarker, 'mouseout', function () {, yourMarker);


Then you can just hover over it and it will close itself.

How to compare two Dates without the time portion?

Using Apache commons you can do:

import org.apache.commons.lang3.time.DateUtils

DateUtils.truncatedEquals(first, second, Calendar.DAY_OF_MONTH)

PG::ConnectionBad - could not connect to server: Connection refused

To fix these type of issues with Postgres and to work with Postgres on Mac OSX, this is probably the BEST and the EASIEST solution that I have found so far:

Just download, install and be happy :)

How do you embed binary data in XML?

You can also Uuencode you original binary data. This format is a bit older but it does the same thing as base63 encoding.

What is Linux’s native GUI API?

GUI is a high level abstraction of capability, so almost everything from XOrg server to OpenGL is ported cross-platform, including for Windows platform. But if by GUI API you mean *nix graphics API then you might be wandering around "Direct Rendering Infrastructure".

How to parse/format dates with LocalDateTime? (Java 8)

Parsing a string with date and time into a particular point in time (Java calls it an "Instant") is quite complicated. Java has been tackling this in several iterations. The latest one, java.time and java.time.chrono, covers almost all needs (except Time Dilation :) ).

However, that complexity brings a lot of confusion.

The key to understand date parsing is:

Why does Java have so many ways to parse a date

  1. There are several systems to measure a time. For instance, the historical Japanese calendars were derived from the time ranges of the reign of the respective emperor or dynasty. Then there is e.g. UNIX timestamp. Fortunately, the whole (business) world managed to use the same.
  2. Historically, the systems were being switched from/to, for various reasons. E.g. from Julian calendar to Gregorian calendar in 1582. So 'western' dates before that need to be treated differently.
  3. And of course the change did not happen at once. Because the calendar came from the headquarteds of some religion and other parts of Europe believed in other dieties, for instance Germany did not switch until the year 1700.

...and why is the LocalDateTime, ZonedDateTime et al. so complicated

  1. There are time zones. A time zone is basically a "stripe"*[1] of the Earth's surface whose authorities follow the same rules of when does it have which time offset. This includes summer time rules.
    The time zones change over time for various areas, mostly based on who conquers whom. And one time zone's rules change over time as well.

  2. There are time offsets. That is not the same as time zones, because a time zone may be e.g. "Prague", but that has summer time offset and winter time offset.
    If you get a timestamp with a time zone, the offset may vary, depending on what part of the year it is in. During the leap hour, the timestamp may mean 2 different times, so without additional information, it can't be reliably converted.
    Note: By timestamp I mean "a string that contains a date and/or time, optionally with a time zone and/or time offset."

  3. Several time zones may share the same time offset for certain periods. For instance, GMT/UTC time zone is the same as "London" time zone when the summer time offset is not in effect.

To make it a bit more complicated (but that's not too important for your use case) :

  1. The scientists observe Earth's dynamic, which changes over time; based on that, they add seconds at the end of individual years. (So 2040-12-31 24:00:00 may be a valid date-time.) This needs regular updates of the metadata that systems use to have the date conversions right. E.g. on Linux, you get regular updates to the Java packages including these new data.
  2. The updates do not always keep the previous behavior for both historical and future timestamps. So it may happen that parsing of the two timestamps around some time zone's change comparing them may give different results when running on different versions of the software. That also applies to comparing between the affected time zone and other time zone.

    Should this cause a bug in your software, consider using some timestamp that does not have such complicated rules, like UNIX timestamp.

  3. Because of 7, for the future dates, we can't convert dates exactly with certainty. So, for instance, current parsing of 8524-02-17 12:00:00 may be off a couple of seconds from the future parsing.

JDK's APIs for this evolved with the contemporary needs

  • The early Java releases had just java.util.Date which had a bit naive approach, assuming that there's just the year, month, day, and time. This quickly did not suffice.
  • Also, the needs of the databases were different, so quite early, java.sql.Date was introduced, with it's own limitations.
  • Because neither covered different calendars and time zones well, the Calendar API was introduced.
  • This still did not cover the complexity of the time zones. And yet, the mix of the above APIs was really a pain to work with. So as Java developers started working on global web applications, libraries that targeted most use cases, like JodaTime, got quickly popular. JodaTime was the de-facto standard for about a decade.
  • But the JDK did not integrate with JodaTime, so working with it was a bit cumbersome. So, after a very long discussion on how to approach the matter, JSR-310 was created mainly based on JodaTime.

How to deal with it in Java's java.time

Determine what type to parse a timestamp to

When you are consuming a timestamp string, you need to know what information it contains. This is the crucial point. If you don't get this right, you end up with a cryptic exceptions like "Can't create Instant" or "Zone offset missing" or "unknown zone id" etc.

Does it contain the date and the time?

  1. Does it have a time offset?
    A time offset is the +hh:mm part. Sometimes, +00:00 may be substituted with Z as 'Zulu time', UTC as Universal Time Coordinated, or GMT as Greenwich Mean Time. These also set the time zone.
    For these timestamps, you use OffsetDateTime.

  2. Does it have a time zone?
    For these timestamps, you use ZonedDateTime.
    Zone is specified either by

    • name ("Prague", "Pacific Standard Time", "PST"), or
    • "zone ID" ("America/Los_Angeles", "Europe/London"), represented by java.time.ZoneId.

    The list of time zones is compiled by a "TZ database", backed by ICAAN.

    According to ZoneId's javadoc, The zone id's can also somehow be specified as Z and offset. I'm not sure how this maps to real zones. If the timestamp, which only has a TZ, falls into a leap hour of time offset change, then it is ambiguous, and the interpretation is subject of ResolverStyle, see below.

  3. If it has neither, then the missing context is assumed or neglected. And the consumer has to decide. So it needs to be parsed as LocalDateTime and converted to OffsetDateTime by adding the missing info:

    • You can assume that it is a UTC time. Add the UTC offset of 0 hours.
    • You can assume that it is a time of the place where the conversion is happening. Convert it by adding the system's time zone.
    • You can neglect and just use it as is. That is useful e.g. to compare or substract two times (see Duration), or when you don't know and it doesn't really matter (e.g. local bus schedule).

Partial time information

  • Based on what the timestamp contains, you can take LocalDate, LocalTime, OffsetTime, MonthDay, Year, or YearMonth out of it.

If you have the full information, you can get a java.time.Instant. This is also internally used to convert between OffsetDateTime and ZonedDateTime.

Figure out how to parse it

There is an extensive documentation on DateTimeFormatter which can both parse a timestamp string and format to string.

The pre-created DateTimeFormatters should cover moreless all standard timestamp formats. For instance, ISO_INSTANT can parse 2011-12-03T10:15:30.123457Z.

If you have some special format, then you can create your own DateTimeFormatter (which is also a parser).

private static final DateTimeFormatter TIMESTAMP_PARSER = new DateTimeFormatterBuilder()

I recommend to look at the source code of DateTimeFormatter and get inspired on how to build one using DateTimeFormatterBuilder. While you're there, also have a look at ResolverStyle which controls whether the parser is LENIENT, SMART or STRICT for the formats and ambiguous information.


Now, the frequent mistake is to go into the complexity of TemporalAccessor. This comes from how the developers were used to work with SimpleDateFormatter.parse(String). Right, DateTimeFormatter.parse("...") gives you TemporalAccessor.

// No need for this!
TemporalAccessor ta = TIMESTAMP_PARSER.parse("2011-... etc");

But, equiped with the knowledge from the previous section, you can conveniently parse into the type you need:

OffsetDateTime myTimestamp = OffsetDateTime.parse("2011-12-03T10:15:30.123457Z", TIMESTAMP_PARSER);

You do not actually need to the DateTimeFormatter either. The types you want to parse have the parse(String) methods.

OffsetDateTime myTimestamp = OffsetDateTime.parse("2011-12-03T10:15:30.123457Z");

Regarding TemporalAccessor, you can use it if you have a vague idea of what information there is in the string, and want to decide at runtime.

I hope I shed some light of understanding onto your soul :)

Note: There's a backport of java.time to Java 6 and 7: ThreeTen-Backport. For Android it has ThreeTenABP.

[1] Not just that they are not stripes, but there also some weird extremes. For instance, some neighboring pacific islands have +14:00 and -11:00 time zones. That means, that while on one island, there is 1st May 3 PM, on another island not so far, it is still 30 April 12 PM (if I counted correctly :) )

Format date and time in a Windows batch script

This batch script will do exactly what the O.P. wants (tested on Windows XP SP3).

I also used that clever registry trick described by "jph" previously which IMHO is the simplest way of getting 100% consistent formatting of the date to "yyyy_MM_dd" on any Windows system new or old. The change to one Registry value for doing this is instantaneous temporary and trivial; it only lasts a few milliseconds before it is immediately reverted back.

Double-click this batch file for an instant demo, Command Prompt window will pop up and display your timestamp . . . . .

:: generates a custom formatted timestamp string using date and time.
:: run this batch file for an instant demo.


REG COPY "HKCU\Control Panel\International" "HKCU\Control Panel\International-Temp" /f 2>nul >nul
REG ADD "HKCU\Control Panel\International" /v sShortDate /d "yyyy_MM_dd" /f 2>nul >nul


REG COPY "HKCU\Control Panel\International-Temp" "HKCU\Control Panel\International" /f 2>nul >nul
REG DELETE "HKCU\Control Panel\International-Temp" /f 2>nul >nul

FOR /F "tokens=1-3 delims=:" %%A IN ('echo %time%') DO (


IF %HOUR%==0 (SET HOUR=00)
IF %HOUR%==1 (SET HOUR=01)
IF %HOUR%==2 (SET HOUR=02)
IF %HOUR%==3 (SET HOUR=03)
IF %HOUR%==4 (SET HOUR=04)
IF %HOUR%==5 (SET HOUR=05)
IF %HOUR%==6 (SET HOUR=06)
IF %HOUR%==7 (SET HOUR=07)
IF %HOUR%==8 (SET HOUR=08)
IF %HOUR%==9 (SET HOUR=09)


ECHO    Generate a custom formatted timestamp string using date and time.
ECHO    Your timestamp is:    %TIMESTAMP%
ECHO    Job is done. Press any key to exit . . .


How to search JSON tree with jQuery

I have kind of similar condition plus my Search Query not limited to particular Object property ( like "John" Search query should be matched with first_name and also with last_name property ). After spending some hours I got this function from Google's Angular project. They have taken care of every possible cases.

/* Seach in Object */

var comparator = function(obj, text) {
if (obj && text && typeof obj === 'object' && typeof text === 'object') {
    for (var objKey in obj) {
        if (objKey.charAt(0) !== '$' &&, objKey) &&
                comparator(obj[objKey], text[objKey])) {
            return true;
    return false;
text = ('' + text).toLowerCase();
return ('' + obj).toLowerCase().indexOf(text) > -1;

var search = function(obj, text) {
if (typeof text == 'string' && text.charAt(0) === '!') {
    return !search(obj, text.substr(1));
switch (typeof obj) {
    case "boolean":
    case "number":
    case "string":
        return comparator(obj, text);
    case "object":
        switch (typeof text) {
            case "object":
                return comparator(obj, text);
                for (var objKey in obj) {
                    if (objKey.charAt(0) !== '$' && search(obj[objKey], text)) {
                        return true;
        return false;
    case "array":
        for (var i = 0; i < obj.length; i++) {
            if (search(obj[i], text)) {
                return true;
        return false;
        return false;

How to select all and copy in vim?

@swpd's answer improved

I use , as a leader key and ,a shortcut does the trick

Add this line if you prefer ,a shortcut

map <Leader>a :%y+<CR> 

I use Ctrl y shortcut to copy

vmap <C-y> y:call system("xclip -i -selection clipboard", getreg("\""))<CR>:call system("xclip -i", getreg("\""))<CR>

And ,v to paste

nmap <Leader>v :call setreg("\"",system("xclip -o -selection clipboard"))<CR>p

Before using this you have to install xclip

$ sudo apt-get install xclip

Edit: When you use :%y+, it can be only pasted to Vim vim Ctrl+Insert shortcut. And

map <C-a> :%y+<Esc>

is not conflicting any settings in my Vimrc.

Java logical operator short-circuiting

Logical OR :- returns true if at least one of the operands evaluate to true. Both operands are evaluated before apply the OR operator.

Short Circuit OR :- if left hand side operand returns true, it returns true without evaluating the right hand side operand.

What does this symbol mean in JavaScript?

See the documentation on MDN about expressions and operators and statements.

Basic keywords and general expressions

this keyword:

var x = function() vs. function x() — Function declaration syntax

(function(){})() — IIFE (Immediately Invoked Function Expression)

someFunction()() — Functions which return other functions

=> — Equal sign, greater than: arrow function expression syntax

|> — Pipe, greater than: Pipeline operator

function*, yield, yield* — Star after function or yield: generator functions

[], Array() — Square brackets: array notation

If the square brackets appear on the left side of an assignment ([a] = ...), or inside a function's parameters, it's a destructuring assignment.

{key: value} — Curly brackets: object literal syntax (not to be confused with blocks)

If the curly brackets appear on the left side of an assignment ({ a } = ...) or inside a function's parameters, it's a destructuring assignment.

`${}` — Backticks, dollar sign with curly brackets: template literals

// — Slashes: regular expression literals

$ — Dollar sign in regex replace patterns: $$, $&, $`, $', $n

() — Parentheses: grouping operator

Property-related expressions

obj.prop, obj[prop], obj["prop"] — Square brackets or dot: property accessors

?., ?.[], ?.() — Question mark, dot: optional chaining operator

:: — Double colon: bind operator

new operator

...iter — Three dots: spread syntax; rest parameters

Increment and decrement

++, -- — Double plus or minus: pre- / post-increment / -decrement operators

Unary and binary (arithmetic, logical, bitwise) operators

delete operator

void operator

+, - — Plus and minus: addition or concatenation, and subtraction operators; unary sign operators

|, &, ^, ~ — Single pipe, ampersand, circumflex, tilde: bitwise OR, AND, XOR, & NOT operators

% — Percent sign: remainder operator

&&, ||, ! — Double ampersand, double pipe, exclamation point: logical operators

?? — Double question mark: nullish-coalescing operator

** — Double star: power operator (exponentiation)

Equality operators

==, === — Equal signs: equality operators

!=, !== — Exclamation point and equal signs: inequality operators

Bit shift operators

<<, >>, >>> — Two or three angle brackets: bit shift operators

Conditional operator

?:… — Question mark and colon: conditional (ternary) operator

Assignment operators

= — Equal sign: assignment operator

%= — Percent equals: remainder assignment

+= — Plus equals: addition assignment operator

&&=, ||=, ??= — Double ampersand, pipe, or question mark, followed by equal sign: logical assignments


Comma operator

, — Comma operator

Control flow

{} — Curly brackets: blocks (not to be confused with object literal syntax)


var, let, const — Declaring variables


label: — Colon: labels

# — Hash (number sign): Private methods or private fields

Browser back button handling

Warn/confirm User if Back button is Pressed is as below.

window.onbeforeunload = function() { return "Your work will be lost."; };

You can get more information using below mentioned links.

Disable Back Button in Browser using JavaScript

I hope this will help to you.

Changing the background color of a drop down list transparent in html

You can actualy fake the transparency of option DOMElements with the following CSS:


option { 
    /* Whatever color  you want */
    background-color: #82caff;

See Demo

The option tag does not support rgba colors yet.

Regular Expressions: Search in list

Full Example (Python 3):
For Python 2.x look into Note below

import re

mylist = ["dog", "cat", "wildcat", "thundercat", "cow", "hooo"]
r = re.compile(".*cat")
newlist = list(filter(r.match, mylist)) # Read Note


['cat', 'wildcat', 'thundercat']


For Python 2.x developers, filter returns a list already. In Python 3.x filter was changed to return an iterator so it has to be converted to list (in order to see it printed out nicely).

Python 3 code example
Python 2.x code example

How to use SQL LIKE condition with multiple values in PostgreSQL?

Following query helped me. Instead of using LIKE, you can use ~*.

select id, name from hosts where name ~* 'julia|lena|jack';

How do I return the response from an asynchronous call?

2017 answer: you can now do exactly what you want in every current browser and node

This is quite simple:

  • Return a Promise
  • Use the 'await', which will tell JavaScript to await the promise to be resolved into a value (like the HTTP response)
  • Add the 'async' keyword to the parent function

Here's a working version of your code:

(async function(){

var response = await superagent.get('...')


await is supported in all current browsers and node 8

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

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

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

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

Switch statement for greater-than/less-than

Updating the accepted answer (can't comment yet). As of 1/12/16 using the demo jsfiddle in chrome, switch-immediate is the fastest solution.

Results: Time resolution: 1.33

   25ms "if-immediate" 150878146 
   29ms "if-indirect" 150878146
   24ms "switch-immediate" 150878146
   128ms "switch-range" 150878146
   45ms "switch-range2" 150878146
   47ms "switch-indirect-array" 150878146
   43ms "array-linear-switch" 150878146
   72ms "array-binary-switch" 150878146


 1.04 (   25ms) if-immediate
 1.21 (   29ms) if-indirect
 1.00 (   24ms) switch-immediate
 5.33 (  128ms) switch-range
 1.88 (   45ms) switch-range2
 1.96 (   47ms) switch-indirect-array
 1.79 (   43ms) array-linear-switch
 3.00 (   72ms) array-binary-switch

Python - Convert a bytes array into JSON format

To convert this bytesarray directly to json, you could first convert the bytesarray to a string with decode(), utf-8 is standard. Change the quotation markers.. The last step is to remove the " from the dumped string, to change the json object from string to list.

dumps(s.decode()).replace("'", '"')[1:-1]

Detecting when user scrolls to bottom of div with jQuery

$(window).on("scroll", function() {
    //get height of the (browser) window aka viewport
    var scrollHeight = $(document).height();
    // get height of the document 
    var scrollPosition = $(window).height() + $(window).scrollTop();
    if ((scrollHeight - scrollPosition) / scrollHeight === 0) {
        // code to run when scroll to bottom of the page

This is the code on github.

Convert data.frame columns from factors to characters

To replace only factors:

i <- sapply(bob, is.factor)
bob[i] <- lapply(bob[i], as.character)

In package dplyr in version 0.5.0 new function mutate_if was introduced:

bob %>% mutate_if(is.factor, as.character) -> bob

...and in version 1.0.0 was replaced by across:

bob %>% mutate(across(where(is.factor), as.character)) -> bob

Package purrr from RStudio gives another alternative:

bob %>% modify_if(is.factor, as.character) -> bob

AngularJS - difference between pristine/dirty and touched/untouched

It's worth mentioning that the validation properties are different for forms and form elements (note that touched and untouched are for fields only):

Input fields have the following states:

$untouched The field has not been touched yet
$touched The field has been touched
$pristine The field has not been modified yet
$dirty The field has been modified
$invalid The field content is not valid
$valid The field content is valid

They are all properties of the input field, and are either true or false.

Forms have the following states:

$pristine No fields have been modified yet
$dirty One or more have been modified
$invalid The form content is not valid
$valid The form content is valid
$submitted The form is submitted

They are all properties of the form, and are either true or false.

How do I replace NA values with zeros in an R dataframe?

See my comment in @gsk3 answer. A simple example:

> m <- matrix(sample(c(NA, 1:10), 100, replace = TRUE), 10)
> d <-
   V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
1   4  3 NA  3  7  6  6 10  6   5
2   9  8  9  5 10 NA  2  1  7   2
3   1  1  6  3  6 NA  1  4  1   6
4  NA  4 NA  7 10  2 NA  4  1   8
5   1  2  4 NA  2  6  2  6  7   4
6  NA  3 NA NA 10  2  1 10  8   4
7   4  4  9 10  9  8  9  4 10  NA
8   5  8  3  2  1  4  5  9  4   7
9   3  9 10  1  9  9 10  5  3   3
10  4  2  2  5 NA  9  7  2  5   5

> d[] <- 0

> d
   V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
1   4  3  0  3  7  6  6 10  6   5
2   9  8  9  5 10  0  2  1  7   2
3   1  1  6  3  6  0  1  4  1   6
4   0  4  0  7 10  2  0  4  1   8
5   1  2  4  0  2  6  2  6  7   4
6   0  3  0  0 10  2  1 10  8   4
7   4  4  9 10  9  8  9  4 10   0
8   5  8  3  2  1  4  5  9  4   7
9   3  9 10  1  9  9 10  5  3   3
10  4  2  2  5  0  9  7  2  5   5

There's no need to apply apply. =)


You should also take a look at norm package. It has a lot of nice features for missing data analysis. =)

Java: Get last element after split

Also you can use java.util.ArrayDeque

String last = new ArrayDeque<>(Arrays.asList("1-2".split("-"))).getLast();

How to parse data in JSON format?

For URL or file, use json.load(). For string with .json content, use json.loads().

#! /usr/bin/python

import json
# from pprint import pprint

json_file = 'my_cube.json'
cube = '1'

with open(json_file) as json_data:
    data = json.load(json_data)

# pprint(data)

print "Dimension: ", data['cubes'][cube]['dim']
print "Measures:  ", data['cubes'][cube]['meas']

How to include() all PHP files from a directory?

If your looking to include a bunch of classes without having to define each class at once you can use:

$directories = array(
foreach ($directories as $directory) {
    foreach(glob($directory . "*.php") as $class) {
        include_once $class;

This way you can just define the class on the php file containing the class and not a whole list of $thisclass = new thisclass();

As for how well it handles all the files? I'm not sure there might be a slight speed decrease with this.

Is there a "between" function in C#?

And for negatives values:

    Public Function IsBetween(Of T)(item As T, pStart As T, pEnd As T) As Boolean '
    Dim Deb As T = pStart
    Dim Fin As T = pEnd
    If (Comparer(Of T).Default.Compare(pStart, pEnd) > 0) Then Deb = pEnd : Fin = pStart
    Return Comparer(Of T).Default.Compare(item, Deb) >= 0 AndAlso Comparer(Of T).Default.Compare(item, Fin) <= 0
End Function

Removing credits link

Add this to your css.

.highcharts-credits {
display: none !important;

Add inline style using Javascript

var div = document.createElement('div');
div.setAttribute('style', 'width:330px; float:left');
div.setAttribute('class', 'well');
var label = document.createElement('label');
label.innerHTML = 'YOUR TEXT HERE';

nginx: [emerg] "server" directive is not allowed here

The path to the nginx.conf file which is the primary Configuration file for Nginx - which is also the file which shall INCLUDE the Path for other Nginx Config files as and when required is /etc/nginx/nginx.conf.

You may access and edit this file by typing this at the terminal

cd /etc/nginx

/etc/nginx$ sudo nano nginx.conf

Further in this file you may Include other files - which can have a SERVER directive as an independent SERVER BLOCK - which need not be within the HTTP or HTTPS blocks, as is clarified in the accepted answer above.

I repeat - if you need a SERVER BLOCK to be defined within the PRIMARY Config file itself than that SERVER BLOCK will have to be defined within an enclosing HTTP or HTTPS block in the /etc/nginx/nginx.conf file which is the primary Configuration file for Nginx.

Also note -its OK if you define , a SERVER BLOCK directly not enclosing it within a HTTP or HTTPS block , in a file located at path /etc/nginx/conf.d . Also to make this work you will need to include the path of this file in the PRIMARY Config file as seen below :-

    include /etc/nginx/conf.d/*.conf; #includes all files of file type.conf

Further to this you may comment out from the PRIMARY Config file , the line

    #include /etc/nginx/sites-available/some_file.conf; # Comment Out 
    include /etc/nginx/conf.d/*.conf; #includes all files of file type.conf

and need not keep any Config Files in /etc/nginx/sites-available/ and also no need to SYMBOLIC Link them to /etc/nginx/sites-enabled/ , kindly note this works for me - in case anyone think it doesnt for them or this kind of config is illegal etc etc , pls do leave a comment so that i may correct myself - thanks .

EDIT :- According to the latest version of the Official Nginx CookBook , we need not create any Configs within - /etc/nginx/sites-enabled/ , this was the older practice and is DEPRECIATED now .

Thus No need for the INCLUDE DIRECTIVE include /etc/nginx/sites-available/some_file.conf; .

Quote from Nginx CookBook page - 5 .

"In some package repositories, this folder is named sites-enabled, and configuration files are linked from a folder named site-available; this convention is depre- cated."

java.lang.UnsupportedClassVersionError: Unsupported major.minor version 51.0 (unable to load class frontend.listener.StartupListener)

What is your output when you do java -version? This will tell you what version the running JVM is.

The Unsupported major.minor version 51.0 error could mean:

  • Your server is running a lower Java version then the one used to compile your Servlet and vice versa

Either way, uninstall all JVM runtimes including JDK and download latest and re-install. That should fix any Unsupported major.minor error as you will have the lastest JRE and JDK (Maybe even newer then the one used to compile the Servlet)

See: (7 Update 25 )

and here: (Java Platform (JDK) 7u25)

for the latest version of the JRE and JDK respectively.


Most likely your code was written in Java7 however maybe it was done using Java7update4 and your system is running Java7update3. Thus they both are effectively the same major version but the minor versions differ. Only the larger minor version is backward compatible with the lower minor version.

Edit 2 : If you have more than one jdk installed on your pc. you should check that Apache Tomcat is using the same one (jre) you are compiling your programs with. If you installed a new jdk after installing apache it normally won't select the new version.

What is event bubbling and capturing?

Description: has a nice description of this. In a nutshell (copied from quirksmode):

Event capturing

When you use event capturing

               | |
---------------| |-----------------
| element1     | |                |
|   -----------| |-----------     |
|   |element2  \ /          |     |
|   -------------------------     |
|        Event CAPTURING          |

the event handler of element1 fires first, the event handler of element2 fires last.

Event bubbling

When you use event bubbling

               / \
---------------| |-----------------
| element1     | |                |
|   -----------| |-----------     |
|   |element2  | |          |     |
|   -------------------------     |
|        Event BUBBLING           |

the event handler of element2 fires first, the event handler of element1 fires last.

What to use?

It depends on what you want to do. There is no better. The difference is the order of the execution of the event handlers. Most of the time it will be fine to fire event handlers in the bubbling phase but it can also be necessary to fire them earlier.

Bash mkdir and subfolders

You can:

mkdir -p folder/subfolder

The -p flag causes any parent directories to be created if necessary.

How to create Drawable from resource

I would just like to add that if you are getting "deprecated" message when using getDrawable(...) you should use the following method from the support library instead.


You do not have to use getResources() when using this method.

This is equivalent to doing something like

Drawable mDrawable;
if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP){
    mDrawable = ContextCompat.getDrawable(getContext(),R.drawable.[name]);
} else {
    mDrawable = getResources().getDrawable([name]);

This works on both pre and post Lollipop versions.

Why does git perform fast-forward merges by default?

Fast-forward merging makes sense for short-lived branches, but in a more complex history, non-fast-forward merging may make the history easier to understand, and make it easier to revert a group of commits.

Warning: Non-fast-forwarding has potential side effects as well. Please review, avoid the 'no-ff' with its "checkpoint commits" that break bisect or blame, and carefully consider whether it should be your default approach for master.

alt text
(From, Vincent Driessen, post "A successful Git branching model")

Incorporating a finished feature on develop

Finished features may be merged into the develop branch to add them to the upcoming release:

$ git checkout develop
Switched to branch 'develop'
$ git merge --no-ff myfeature
Updating ea1b82a..05e9557
(Summary of changes)
$ git branch -d myfeature
Deleted branch myfeature (was 05e9557).
$ git push origin develop

The --no-ff flag causes the merge to always create a new commit object, even if the merge could be performed with a fast-forward. This avoids losing information about the historical existence of a feature branch and groups together all commits that together added the feature.

Jakub Narebski also mentions the config merge.ff:

By default, Git does not create an extra merge commit when merging a commit that is a descendant of the current commit. Instead, the tip of the current branch is fast-forwarded.
When set to false, this variable tells Git to create an extra merge commit in such a case (equivalent to giving the --no-ff option from the command line).
When set to 'only', only such fast-forward merges are allowed (equivalent to giving the --ff-only option from the command line).

The fast-forward is the default because:

  • short-lived branches are very easy to create and use in Git
  • short-lived branches often isolate many commits that can be reorganized freely within that branch
  • those commits are actually part of the main branch: once reorganized, the main branch is fast-forwarded to include them.

But if you anticipate an iterative workflow on one topic/feature branch (i.e., I merge, then I go back to this feature branch and add some more commits), then it is useful to include only the merge in the main branch, rather than all the intermediate commits of the feature branch.

In this case, you can end up setting this kind of config file:

[branch "master"]
# This is the list of cmdline options that should be added to git-merge 
# when I merge commits into the master branch.

# The option --no-commit instructs git not to commit the merge
# by default. This allows me to do some final adjustment to the commit log
# message before it gets commited. I often use this to add extra info to
# the merge message or rewrite my local branch names in the commit message
# to branch names that are more understandable to the casual reader of the git log.

# Option --no-ff instructs git to always record a merge commit, even if
# the branch being merged into can be fast-forwarded. This is often the
# case when you create a short-lived topic branch which tracks master, do
# some changes on the topic branch and then merge the changes into the
# master which remained unchanged while you were doing your work on the
# topic branch. In this case the master branch can be fast-forwarded (that
# is the tip of the master branch can be updated to point to the tip of
# the topic branch) and this is what git does by default. With --no-ff
# option set, git creates a real merge commit which records the fact that
# another branch was merged. I find this easier to understand and read in
# the log.

mergeoptions = --no-commit --no-ff

The OP adds in the comments:

I see some sense in fast-forward for [short-lived] branches, but making it the default action means that git assumes you... often have [short-lived] branches. Reasonable?

Jefromi answers:

I think the lifetime of branches varies greatly from user to user. Among experienced users, though, there's probably a tendency to have far more short-lived branches.

To me, a short-lived branch is one that I create in order to make a certain operation easier (rebasing, likely, or quick patching and testing), and then immediately delete once I'm done.
That means it likely should be absorbed into the topic branch it forked from, and the topic branch will be merged as one branch. No one needs to know what I did internally in order to create the series of commits implementing that given feature.

More generally, I add:

it really depends on your development workflow:

  • if it is linear, one branch makes sense.
  • If you need to isolate features and work on them for a long period of time and repeatedly merge them, several branches make sense.

See "When should you branch?"

Actually, when you consider the Mercurial branch model, it is at its core one branch per repository (even though you can create anonymous heads, bookmarks and even named branches)
See "Git and Mercurial - Compare and Contrast".

Mercurial, by default, uses anonymous lightweight codelines, which in its terminology are called "heads".
Git uses lightweight named branches, with injective mapping to map names of branches in remote repository to names of remote-tracking branches.
Git "forces" you to name branches (well, with the exception of a single unnamed branch, which is a situation called a "detached HEAD"), but I think this works better with branch-heavy workflows such as topic branch workflow, meaning multiple branches in a single repository paradigm.

Dynamically Add Variable Name Value Pairs to JSON Object

if my understanding of your initial JSON is correct, either of these solutions might help you loop through all ip ids & assign each one, a new object.

// initial JSON
var ips = {ipId1: {}, ipId2: {}};

// Solution1
Object.keys(ips).forEach(function(key) {
  ips[key] = {name: 'value', anotherName: 'another value'};

// Solution 2
Object.keys(ips).forEach(function(key) {
  Object.assign(ips[key],{name: 'value', anotherName: 'another value'});

To confirm:

console.log(JSON.stringify(ips, null, 2));

The above statement spits:

  "ipId1": {
    "anotherName":"another value"
  "ipId2": {
    "anotherName":"another value"

Validation of radio button group using jQuery validation plugin

With newer releases of jquery (1.3+ I think), all you have to do is set one of the members of the radio set to be required and jquery will take care of the rest:

<input type="radio" name="myoptions" value="blue" class="required"> Blue<br />
<input type="radio" name="myoptions" value="red"> Red<br />
<input type="radio" name="myoptions" value="green"> Green

The above would require at least 1 of the 3 radio options w/ the name of "my options" to be selected before proceeding.

The label suggestion by Mahes, btw, works wonderfully!

SOAP or REST for Web Services?

I'd recommend you go with REST first - if you're using Java look at JAX-RS and the Jersey implementation. REST is much simpler and easy to interop in many languages.

As others have said in this thread, the problem with SOAP is its complexity when the other WS-* specifications come in and there are countless interop issues if you stray into the wrong parts of WSDL, XSDs, SOAP, WS-Addressing etc.

The best way to judge the REST v SOAP debate is look on the internet - pretty much all the big players in the web space, google, amazon, ebay, twitter et al - tend to use and prefer RESTful APIs over the SOAP ones.

The other nice approach to going with REST is that you can reuse lots of code and infratructure between a web application and a REST front end. e.g. rendering HTML versus XML versus JSON of your resources is normally pretty easy with frameworks like JAX-RS and implicit views - plus its easy to work with RESTful resources using a web browser

How to read text file in JavaScript

This can be done quite easily using javascript XMLHttpRequest() class (AJAX):

function FileHelper()

    FileHelper.readStringFromFileAtPath = function(pathOfFileToReadFrom)
        var request = new XMLHttpRequest();"GET", pathOfFileToReadFrom, false);
        var returnValue = request.responseText;

        return returnValue;


var text = FileHelper.readStringFromFileAtPath ( "mytext.txt" );

Receiver not registered exception error?

EDIT: This is the answer for inazaruk and electrichead... I had run into a similar issue to them and found out the following...

There is a long-standing bug for this problem here:

Looks like it started around Android 2.1 and has been present in all of the Android 2.x releases since. I'm not sure if it is still a problem in Android 3.x or 4.x though.

Anyway, this StackOverflow post explains how to workaround the problem correctly (it doesn't look relevant by the URL but I promise it is)

Why does keyboard-slide crash my app?

PhpMyAdmin "Wrong permissions on configuration file, should not be world writable!"

Just in case, someone out there having same issue but changing file permission doesn't solve the issue, add this line to your file

// other config goes here . . . 
$cfg['CheckConfigurationPermissions'] = false;

And you're good to go.

In my case, I'm using windows 10 WSL with phpmyadmin installed on D: drive. There's no way to (for now) change file permission on local disk through WSL unless your installation directory is inside WSL filesystem it-self. There's updates according to this issue, but still on insider build.


Linq to Entities join vs groupjoin


Suppose you have two lists:

Id  Value
1   A
2   B
3   C

Id  ChildValue
1   a1
1   a2
1   a3
2   b1
2   b2

When you Join the two lists on the Id field the result will be:

Value ChildValue
A     a1
A     a2
A     a3
B     b1
B     b2

When you GroupJoin the two lists on the Id field the result will be:

Value  ChildValues
A      [a1, a2, a3]
B      [b1, b2]
C      []

So Join produces a flat (tabular) result of parent and child values.
GroupJoin produces a list of entries in the first list, each with a group of joined entries in the second list.

That's why Join is the equivalent of INNER JOIN in SQL: there are no entries for C. While GroupJoin is the equivalent of OUTER JOIN: C is in the result set, but with an empty list of related entries (in an SQL result set there would be a row C - null).


So let the two lists be IEnumerable<Parent> and IEnumerable<Child> respectively. (In case of Linq to Entities: IQueryable<T>).

Join syntax would be

from p in Parent
join c in Child on p.Id equals c.Id
select new { p.Value, c.ChildValue }

returning an IEnumerable<X> where X is an anonymous type with two properties, Value and ChildValue. This query syntax uses the Join method under the hood.

GroupJoin syntax would be

from p in Parent
join c in Child on p.Id equals c.Id into g
select new { Parent = p, Children = g }

returning an IEnumerable<Y> where Y is an anonymous type consisting of one property of type Parent and a property of type IEnumerable<Child>. This query syntax uses the GroupJoin method under the hood.

We could just do select g in the latter query, which would select an IEnumerable<IEnumerable<Child>>, say a list of lists. In many cases the select with the parent included is more useful.

Some use cases

1. Producing a flat outer join.

As said, the statement ...

from p in Parent
join c in Child on p.Id equals c.Id into g
select new { Parent = p, Children = g }

... produces a list of parents with child groups. This can be turned into a flat list of parent-child pairs by two small additions:

from p in parents
join c in children on p.Id equals c.Id into g // <= into
from c in g.DefaultIfEmpty()               // <= flattens the groups
select new { Parent = p.Value, Child = c?.ChildValue }

The result is similar to

Value Child
A     a1
A     a2
A     a3
B     b1
B     b2
C     (null)

Note that the range variable c is reused in the above statement. Doing this, any join statement can simply be converted to an outer join by adding the equivalent of into g from c in g.DefaultIfEmpty() to an existing join statement.

This is where query (or comprehensive) syntax shines. Method (or fluent) syntax shows what really happens, but it's hard to write:

parents.GroupJoin(children, p => p.Id, c => c.Id, (p, c) => new { p, c })
       .SelectMany(x => x.c.DefaultIfEmpty(), (x,c) => new { x.p.Value, c?.ChildValue } )

So a flat outer join in LINQ is a GroupJoin, flattened by SelectMany.

2. Preserving order

Suppose the list of parents is a bit longer. Some UI produces a list of selected parents as Id values in a fixed order. Let's use:

var ids = new[] { 3,7,2,4 };

Now the selected parents must be filtered from the parents list in this exact order.

If we do ...

var result = parents.Where(p => ids.Contains(p.Id));

... the order of parents will determine the result. If the parents are ordered by Id, the result will be parents 2, 3, 4, 7. Not good. However, we can also use join to filter the list. And by using ids as first list, the order will be preserved:

from id in ids
join p in parents on id equals p.Id
select p

The result is parents 3, 7, 2, 4.

Set content of HTML <span> with Javascript

To do it without using a JavaScript library such as jQuery, you'd do it like this:

var span = document.getElementById("myspan"),
    text = document.createTextNode(''+intValue);
span.innerHTML = ''; // clear existing

If you do want to use jQuery, it's just this:


Catch error if iframe src fails to load . Error :-"Refused to display '' in a frame.."

As explained in the accepted answer,, you need to check via a server.

Because there's no reliable way to check this in the browser, I suggest you build yourself a quick server endpoint that you can use to check if any url is loadable via iframe. Once your server is up and running, just send a AJAX request to it to check any url by providing the url in the query string as url (or whatever your server desires). Here's the server code in NodeJs:

const express = require('express')_x000D_
const app = express()_x000D_
app.get('/checkCanLoadIframeUrl', (req, res) => {_x000D_
  const request = require('request')_x000D_
  const Q = require('q')_x000D_
  return Q.Promise((resolve) => {_x000D_
    const url = decodeURIComponent(req.query.url)_x000D_
    const deafultTimeout = setTimeout(() => {_x000D_
      // Default to false if no response after 10 seconds_x000D_
    }, 10000)_x000D_
        jar: true /** Maintain cookies through redirects */_x000D_
      .on('response', (remoteRes) => {_x000D_
        const opts = (remoteRes.headers['x-frame-options'] || '').toLowerCase()_x000D_
        resolve(!opts || (opts !== 'deny' && opts !== 'sameorigin'))_x000D_
      .on('error', function() {_x000D_
  }).then((result) => {_x000D_
    return res.status(200).json(!!result)_x000D_
app.listen(process.env.PORT || 3100)

What is a difference between unsigned int and signed int in C?

Assuming int is a 16 bit integer (which depends on the C implementation, most are 32 bit nowadays) the bit representation differs like the following:

 5 = 0000000000000101
-5 = 1111111111111011

if binary 1111111111111011 would be set to an unsigned int, it would be decimal 65531.

Finding the average of a list

In terms of efficiency and speed, these are the results that I got testing the other answers:

# test mean caculation

import timeit
import statistics
import numpy as np
from functools import reduce
import pandas as pd

LIST_RANGE = 10000000000

l = list(range(10))

def mean1():
    return statistics.mean(l)

def mean2():
    return sum(l) / len(l)

def mean3():
    return np.mean(l)

def mean4():
    return np.array(l).mean()

def mean5():
    return reduce(lambda x, y: x + y / float(len(l)), l, 0)

def mean6():
    return pd.Series(l).mean()

for func in [mean1, mean2, mean3, mean4, mean5, mean6]:
    print(f"{func.__name__} took: ",  timeit.timeit(stmt=func, number=NUMBERS_OF_TIMES_TO_TEST))

and the results:

mean1 took:  0.17030245899968577
mean2 took:  0.002183011999932205
mean3 took:  0.09744236000005913
mean4 took:  0.07070840100004716
mean5 took:  0.022754742999950395
mean6 took:  1.6689282460001778

so clearly the winner is: sum(l) / len(l)

How to validate an email address using a regular expression?

This regex is from Perl's Email::Valid library. I believe it to be the most accurate, it matches all 822. And, it is based on the regular expression in the O'Reilly book:

Regular expression built using Jeffrey Friedl's example in Mastering Regular Expressions (

$RFC822PAT = <<'EOF';

check null,empty or undefined angularjs

You can do simple check

if(!a) {
   // do something when `a` is not undefined, null, ''.

How do I exit from a function?

Use the return keyword.

From MSDN:

The return statement terminates execution of the method in which it appears and returns control to the calling method. It can also return the value of the optional expression. If the method is of the type void, the return statement can be omitted.

So in your case, the usage would be:

private void button1_Click(object sender, EventArgs e)
    if (textBox1.Text == "" || textBox2.Text == "" || textBox3.Text == "")
        return; //exit this event

What is an Intent in Android?

What is an Intent ?

An Intent is basically a message that is passed between components (such as Activities, Services, Broadcast Receivers, and Content Providers). So, it is almost equivalent to parameters passed to API calls. The fundamental differences between API calls and invoking components via intents are:

  • API calls are synchronous while intent-based invocations are asynchronous.
  • API calls are compile-time binding while intent-based calls are run-time binding.

Of course, Intents can be made to work exactly like API calls by using what are called explicit intents, which will be explained later. But more often than not, implicit intents are the way to go and that is what is explained here.

One component that wants to invoke another has to only express its intent to do a job. And any other component that exists and has claimed that it can do such a job through intent-filters, is invoked by the Android platform to accomplish the job. This means, neither components are aware of each other's existence but can still work together to give the desired result for the end-user.

This invisible connection between components is achieved through the combination of intents, intent-filters and the Android platform.

This leads to huge possibilities like:

  • Mix and match or rather plug and play of components at runtime.
  • Replacing the inbuilt Android applications with custom developed applications.
  • Component level reuse within and across applications.
  • Service orientation to the most granular level, if I may say.

Here are additional technical details about Intents from the Android documentation.

An intent is an abstract description of an operation to be performed. It can be used with startActivity to launch an Activity, broadcastIntent to send it to any interested BroadcastReceiver components, and startService(Intent) or bindService(Intent, ServiceConnection, int) to communicate with a Background Service.

An Intent provides a facility for performing late runtime binding between the code in different applications. Its most significant use is in the launching of activities, where it can be thought of as the glue between activities. It is basically a passive data structure holding an abstract description of an action to be performed. The primary pieces of information in an intent are:

  • action The general action to be performed, such as ACTION_VIEW, ACTION_EDIT, ACTION_MAIN, etc.
  • data The data to operate on, such as a person record in the contacts database, expressed as a Uri.

Learn more

How to watch for a route change in AngularJS?

If you don't want to place the watch inside a specific controller, you can add the watch for the whole aplication in Angular app run()

var myApp = angular.module('myApp', []);$rootScope) {
    $rootScope.$on("$locationChangeStart", function(event, next, current) { 
        // handle route changes     

In Firebase, is there a way to get the number of children of a node without loading all the node data?

write a cloud function to and update the node count.

// below function to get the given node count.
const functions = require('firebase-functions');
const admin = require('firebase-admin');

exports.userscount = functions.database.ref('/users/')
    .onWrite(event => {

      console.log('users number : ',;


Refer :

root--| |-users ( this node contains all users list) |
|-count |-userscount : (this node added dynamically by cloud function with the user count)

How to import an excel file in to a MySQL database

For a step by step example for importing Excel 2007 into MySQL with correct encoding (UTF-8) search for this comment:

"Posted by Mike Laird on October 13 2010 12:50am"

in the next URL:

How to select an element with 2 classes

You can chain class selectors without a space between them:

.a.b {
     color: #666;

Note that, if it matters to you, IE6 treats .a.b as .b, so in that browser both div.a.b and div.b will have gray text. See this answer for a comparison between proper browsers and IE6.

How to click a browser button with JavaScript automatically?

This will give you some control over the clicking, and looks tidy

var timeOut = 0;
function onClick(but)
    timeOut = setTimeout(function (){onClick(but)},1000);
<button onclick="onClick(this)">Start clicking</button>

range() for floats

Is there a range() equivalent for floats in Python? NO Use this:

def f_range(start, end, step):
    a = range(int(start/0.01), int(end/0.01), int(step/0.01))
    var = []
    for item in a:
    return var

Set a thin border using .css() in javascript

After a few futile hours battling with a 'SyntaxError: missing : after property id' message I can now expand on this topic:

border-width is a valid css property but it is not included in the jQuery css oject definition, so .css({border-width: '2px'}) will cause an error, but it's quite happy with .css({'border-width': '2px'}), presumably property names in quotes are just passed on as received.

Getting each individual digit from a whole integer


int main() {
int num; //given integer
int reminder;
int rev=0; //To reverse the given integer
int count=1;

printf("Enter the integer:");

/*First while loop will reverse the number*/
/*Second while loop will give the number from left to right*/
    printf("The %d digit is %d\n",count, reminder);
    count++; //to give the number from left to right 
return (EXIT_SUCCESS);}

Centering a Twitter Bootstrap button

If you have more than one button, then you can do the following.

<div class="center-block" style="max-width:400px">
  <a href="#" class="btn btn-success">Accept</a>
  <a href="#" class="btn btn-danger"> Reject</a>

Converting PKCS#12 certificate into PEM using OpenSSL

If you can use Python, it is even easier if you have the pyopenssl module. Here it is:

from OpenSSL import crypto

# May require "" for empty password depending on version

with open("push.p12", "rb") as file:
    p12 = crypto.load_pkcs12(, "my_passphrase")

# PEM formatted private key
print crypto.dump_privatekey(crypto.FILETYPE_PEM, p12.get_privatekey())

# PEM formatted certificate
print crypto.dump_certificate(crypto.FILETYPE_PEM, p12.get_certificate())

What is a stack pointer used for in microprocessors?

The stack pointer stores the address of the most recent entry that was pushed onto the stack.

To push a value onto the stack, the stack pointer is incremented to point to the next physical memory address, and the new value is copied to that address in memory.

To pop a value from the stack, the value is copied from the address of the stack pointer, and the stack pointer is decremented, pointing it to the next available item in the stack.

The most typical use of a hardware stack is to store the return address of a subroutine call. When the subroutine is finished executing, the return address is popped off the top of the stack and placed in the Program Counter register, causing the processor to resume execution at the next instruction following the call to the subroutine.

How to overwrite styling in Twitter Bootstrap

All these tips will work, but a simpler way might be to include your stylesheet after the Bootstrap styles.

If you include your css (site-specific.css) after Bootstrap's (bootstrap.css), you can override rules by redefining them.

For example, if this is how you include CSS in your <head>

<link rel="stylesheet" href="css/bootstrap.css" />
<link rel="stylesheet" href="css/site-specific.css" />

You can simply move the sidebar to the right by writing (in your site-specific.css file):

.sidebar {
    float: right;

Forgive the lack of HAML and SASS, I do not know them well enough to write tutorials in them.

Factory Pattern. When to use factory methods?

Factory classes are more heavyweight, but give you certain advantages. In cases when you need to build your objects from multiple, raw data sources they allow you to encapsulate only the building logic (and maybe the aggregation of the data) in one place. There it can be tested in abstract without being concerned with the object interface.

I have found this a useful pattern, particularly where I am unable to replace and inadequate ORM and want to efficiently instantiate many objects from DB table joins or stored procedures.

How do I get a decimal value when using the division operator in Python?

You might want to look at Python's decimal package, also. This will provide nice decimal results.

>>> decimal.Decimal('4')/100

What is the difference between MOV and LEA?

LEA (Load Effective Address) is a shift-and-add instruction. It was added to 8086 because hardware is there to decode and calculate adressing modes.

Automatically start a Windows Service on install

In your Installer class, add a handler for the AfterInstall event. You can then call the ServiceController in the event handler to start the service.

using System.ServiceProcess;
public ServiceInstaller()
    //... Installer code here
    this.AfterInstall += new InstallEventHandler(ServiceInstaller_AfterInstall);

void ServiceInstaller_AfterInstall(object sender, InstallEventArgs e)
    ServiceInstaller serviceInstaller = (ServiceInstaller)sender;

    using (ServiceController sc = new ServiceController(serviceInstaller.ServiceName))

Now when you run InstallUtil on your installer, it will install and then start up the service automatically.

How do I delete multiple rows in Entity Framework (without foreach)

Entity Framework Core

3.1 3.0 2.2 2.1 2.0 1.1 1.0

using (YourContext context = new YourContext ())
    var widgets = context.Widgets.Where(w => w.WidgetId == widgetId);


Removes the given collection of entities from the context underlying the set with each entity being put into the Deleted state such that it will be deleted from the database when SaveChanges is called.


Note that if System.Data.Entity.Infrastructure.DbContextConfiguration.AutoDetectChangesEnabled is set to true (which is the default), then DetectChanges will be called once before delete any entities and will not be called again. This means that in some situations RemoveRange may perform significantly better than calling Remove multiple times would do. Note that if any entity exists in the context in the Added state, then this method will cause it to be detached from the context. This is because an Added entity is assumed not to exist in the database such that trying to delete it does not make sense.

How to read input from console in a batch file?

If you're just quickly looking to keep a cmd instance open instead of exiting immediately, simply doing the following is enough

set /p asd="Hit enter to continue"

at the end of your script and it'll keep the window open.

Note that this'll set asd as an environment variable, and can be replaced with anything else.

Can we instantiate an abstract class directly?

You can't directly instantiate an abstract class, but you can create an anonymous class when there is no concrete class:

public class AbstractTest {
    public static void main(final String... args) {
        final Printer p = new Printer() {
            void printSomethingOther() {
            public void print() {
                printSomethingOther(); // works fine
        //p.printSomethingOther(); // does not work

abstract class Printer {
    public void print() {

This works with interfaces, too.

! [rejected] master -> master (fetch first)

Sometimes it happens when you duplicate files typically README sort of.

List directory tree structure in python?

A solution without your indentation:

for path, dirs, files in os.walk(given_path):
  print path
  for f in files:
    print f

os.walk already does the top-down, depth-first walk you are looking for.

Ignoring the dirs list prevents the overlapping you mention.

Error converting data types when importing from Excel to SQL Server 2008

There seems to be a really easy solution when dealing with data type issues.

Basically, at the end of Excel connection string, add ;IMEX=1;"

Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\\YOURSERVER\shared\Client Projects\FOLDER\Data\FILE.xls;Extended Properties="EXCEL 8.0;HDR=YES;IMEX=1";

This will resolve data type issues such as columns where values are mixed with text and numbers.

To get to connection property, right click on Excel connection manager below control flow and hit properties. It'll be to the right under solution explorer. Hope that helps.

How to reset selected file with input tag file type in Angular 2?

I typically reset my file input after capturing the selected files. No need to push a button, you have everything required in the $event object that you're passing to onChange:

onChange(event) {
  // Get your files
  const files: FileList =;

  // Clear the input
  event.srcElement.value = null;

Different workflow, but the OP doesn't mention pushing a button is a requirement...

How to get JSON objects value if its name contains dots?

If json object key/name contains dot......! like

var myJson = {"":"vikas","my.age":27}

Than you can access like


How to find the Windows version from the PowerShell command line

Using Windows Powershell, it possible to get the data you need in the following way


(Get-WmiObject -class Win32_OperatingSystem).Caption


(Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion" -Name ReleaseId).ReleaseId


(Get-CimInstance Win32_OperatingSystem).version

resize font to fit in a div (on one line)

Here are 3 functions I use frequently to get the text width, height and adjust the size to the container's width.

  • getTextWidth() will return you the actual width of the text contained in the initiator.
  • getTextHeight(width) will return the actual height of the wrapped text contained in the initiator with a certain specified width.
  • autoTextSize(minSize, maxSize, truncate) will size the text within the container so it fits, considering a minimum and maximum size.
  • autoTruncateText() will only show the characters the user can actually see and end the text with '...'.
(function ($) {
  $.fn.getTextWidth = function() {
    var spanText = $("BODY #spanCalculateTextWidth");

    if (spanText.size() <= 0) {
      spanText = $("<span id='spanCalculateTextWidth' style='filter: alpha(0);'></span>");

    var valu = this.val();
    if (!valu) valu = this.text();


      "fontSize": this.css('fontSize'),
      "fontWeight": this.css('fontWeight'),
      "fontFamily": this.css('fontFamily'),
      "position": "absolute",
      "top": 0,
      "opacity": 0,
      "left": -2000

    return spanText.outerWidth() + parseInt(this.css('paddingLeft')) + 'px';

  $.fn.getTextHeight = function(width) {
    var spanText = $("BODY #spanCalculateTextHeight");

    if (spanText.size() <= 0) {
      spanText = $("<span id='spanCalculateTextHeight'></span>");

    var valu = this.val();
    if (!valu) valu = this.text();


      "fontSize": this.css('fontSize'),
      "fontWeight": this.css('fontWeight'),
      "fontFamily": this.css('fontFamily'),
      "top": 0,
      "left": -1 * parseInt(width) + 'px',
      "position": 'absolute',
      "display": "inline-block",
      "width": width

    return spanText.innerHeight() + 'px';

   * Adjust the font-size of the text so it fits the container.
   * @param minSize     Minimum font size?
   * @param maxSize     Maximum font size?
   * @param truncate    Truncate text after sizing to make sure it fits?
  $.fn.autoTextSize = function(minSize, maxSize, truncate) {
    var _self = this,
        _width = _self.innerWidth(),
        _textWidth = parseInt(_self.getTextWidth()),
        _fontSize = parseInt(_self.css('font-size'));

    while (_width < _textWidth || (maxSize && _fontSize > parseInt(maxSize))) {
      if (minSize && _fontSize <= parseInt(minSize)) break;

      _self.css('font-size', _fontSize + 'px');

      _textWidth = parseInt(_self.getTextWidth());

    if (truncate) _self.autoTruncateText();

   * Function that truncates the text inside a container according to the
   * width and height of that container. In other words, makes it fit by chopping
   * off characters and adding '...'.
  $.fn.autoTruncateText = function() {
    var _self = this,
        _width = _self.outerWidth(),
        _textHeight = parseInt(_self.getTextHeight(_width)),
        _text = _self.text();

    // As long as the height of the text is higher than that
    // of the container, we'll keep removing a character.
    while (_textHeight > _self.outerHeight()) {
      _text = _text.slice(0,-1);
      _textHeight = parseInt(_self.getTextHeight(_width));
      _truncated = true;

    // When we actually truncated the text, we'll remove the last
    // 3 characters and replace it with '...'.
    if (!_truncated) return;
    _text = _text.slice(0, -3);

    // Make sure there is no dot or space right in front of '...'.
    var lastChar = _text[_text.length - 1];
    if (lastChar == ' ' || lastChar == '.') _text = _text.slice(0, -1);
    _self.text(_text + '...');

AngularJS : automatically detect change in model

And if you need to style your form elements according to it's state (modified/not modified) dynamically or to test whether some values has actually changed, you can use the following module, developed by myself:

It adds additional properties and methods to the form and it's child elements. With it, you can test whether some element contains new data or even test if entire form has new unsaved data.

You can setup the following watch: $scope.$watch('myForm.modified', handler) and your handler will be called if some form elements actually contains new data or if it reversed to initial state.

Also, you can use modified property of individual form elements to actually reduce amount of data sent to a server via AJAX call. There is no need to send unchanged data.

As a bonus, you can revert your form to initial state via call to form's reset() method.

You can find the module's demo here:


Error Message: Type or namespace definition, or end-of-file expected

  1. Make sure you have System.Web referenced
  2. Get rid of the two } at the end.

ORA-01652: unable to extend temp segment by 128 in tablespace SYSTEM: How to extend?

Each tablespace has one or more datafiles that it uses to store data.

The max size of a datafile depends on the block size of the database. I believe that, by default, that leaves with you with a max of 32gb per datafile.

To find out if the actual limit is 32gb, run the following:

select value from v$parameter where name = 'db_block_size';

Compare the result you get with the first column below, and that will indicate what your max datafile size is.

I have Oracle Personal Edition 11g r2 and in a default install it had an 8,192 block size (32gb per data file).

Block Sz   Max Datafile Sz (Gb)   Max DB Sz (Tb)

--------   --------------------   --------------

   2,048                  8,192          524,264

   4,096                 16,384        1,048,528

   8,192                 32,768        2,097,056

  16,384                 65,536        4,194,112

  32,768                131,072        8,388,224

You can run this query to find what datafiles you have, what tablespaces they are associated with, and what you've currrently set the max file size to (which cannot exceed the aforementioned 32gb):

select bytes/1024/1024 as mb_size,
       maxbytes/1024/1024 as maxsize_set,
from   dba_data_files x

MAXSIZE_SET is the maximum size you've set the datafile to. Also relevant is whether you've set the AUTOEXTEND option to ON (its name does what it implies).

If your datafile has a low max size or autoextend is not on you could simply run:

alter database datafile 'path_to_your_file\that_file.DBF' autoextend on maxsize unlimited;

However if its size is at/near 32gb an autoextend is on, then yes, you do need another datafile for the tablespace:

alter tablespace system add datafile 'path_to_your_datafiles_folder\name_of_df_you_want.dbf' size 10m autoextend on maxsize unlimited;

Can an AWS Lambda function call another

You should chain your Lambda functions via SNS. This approach provides good performance, latency and scalability for minimal effort.

Your first Lambda publishes messages to your SNS Topic and the second Lambda is subscribed to this topic. As soon as messages arrive in the topic, second Lambda gets executed with the message as it's input parameter.

See Invoking Lambda functions using Amazon SNS notifications.

You can also use this approach to Invoke cross-account Lambda functions via SNS.

Count work days between two dates

If you need to add work days to a given date, you can create a function that depends on a calendar table, described below:

  IsWorkDay BIT

--fill the rows with normal days, weekends and holidays.

create function AddWorkingDays (@initialDate smalldatetime, @numberOfDays int)
    returns smalldatetime as 

        declare @result smalldatetime
        set @result = 
            select t.dt from
                select dt, ROW_NUMBER() over (order by dt) as daysAhead from calendar 
                where dt > @initialDate
                and IsWorkDay = 1
                ) t
            where t.daysAhead = @numberOfDays

        return @result

You don't have write permissions for the /var/lib/gems/2.3.0 directory

(January 2019) To install Ruby using the Rbenv script, follow these steps:

1. First, update the packages index and install the packages required for the ruby-build tool to build Ruby from source:

sudo apt-get remove ruby
sudo apt update
sudo apt install git curl libssl-dev libreadline-dev zlib1g-dev autoconf bison build-essential libyaml-dev libreadline-dev libncurses5-dev libffi-dev libgdbm-dev

2. Next, run the following curl command to install both rbenv and ruby-build:

curl -sL | bash -

3. Add $HOME/.rbenv/bin to the system PATH.

If you are using Bash, run:

echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(rbenv init -)"' >> ~/.bashrc
source ~/.bashrc

If you are using Zsh run:

echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.zshrc
echo 'eval "$(rbenv init -)"' >> ~/.zshrc
source ~/.zshrc

4. Install the latest stable version of Ruby and set it as a default version with:

rbenv install 2.5.1
rbenv global 2.5.1

To list all available Ruby versions you can use: rbenv install -l

5. Verify that Ruby was properly installed by printing out the version number:

ruby -v

# Output
ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux]

SOURCE: How To Install Ruby on Ubuntu 18.04

EDIT: Install rubygems:

sudo apt-get install rubygems

How to debug .htaccess RewriteRule not working

Generally any change in the .htaccess should have visible effects. If no effect, check your configuration apache files, something like:

<Directory ..>
    AllowOverride None

Should be changed to

AllowOverride All

And you'll be able to change directives in .htaccess files.

What is the difference between onBlur and onChange attribute in HTML?

The onBlur event is fired when you have moved away from an object without necessarily having changed its value.

The onChange event is only called when you have changed the value of the field and it loses focus.

You might want to take a look at quirksmode's intro to events. This is a great place to get info on what's going on in your browser when you interact with it. His book is good too.

Upgrading Node.js to latest version

Following Upgrading Node.js to latest version

sudo npm cache clean -f
sudo npm install -g n
sudo n stable

sudo ln -sf /usr/local/n/versions/node/<VERSION>/bin/node /usr/bin/node

For Upgrading Node.js to latest version

sudo n latest

If you need to do Undo then follow command

sudo apt-get install --reinstall nodejs-legacy     # fix /usr/bin/node
sudo n rm 6.0.0     # replace number with version of Node that was installed
sudo npm uninstall -g n

This method of upgrading node is now unstable and should not be used. The best way to manage Node.js versions is to use NVM: Node Version Management.!


You can read the installation steps on the nvm [GitHub page][1]. There are only two easy steps for installation and configuration. Using nvm

If you work with a lot of different Node.js utilities, you know that sometimes you need to quickly switch to other versions of Node.js without hosing your entire machine. That's where you can use nvm to download, install, and use different versions of Node.js:

nvm install 4.0

At any given time you can switch to another with use:

nvm use 0.12

Checking the equality of two slices

If you have two []byte, compare them using bytes.Equal. The Golang documentation says:

Equal returns a boolean reporting whether a and b are the same length and contain the same bytes. A nil argument is equivalent to an empty slice.


package main

import (

func main() {
    a := []byte {1,2,3}
    b := []byte {1,2,3}
    c := []byte {1,2,2}

    fmt.Println(bytes.Equal(a, b))
    fmt.Println(bytes.Equal(a, c))

This will print


Simple post to Web Api

It's been quite sometime since I asked this question. Now I understand it more clearly, I'm going to put a more complete answer to help others.

In Web API, it's very simple to remember how parameter binding is happening.

  • if you POST simple types, Web API tries to bind it from the URL
  • if you POST complex type, Web API tries to bind it from the body of the request (this uses a media-type formatter).

  • If you want to bind a complex type from the URL, you'll use [FromUri] in your action parameter. The limitation of this is down to how long your data going to be and if it exceeds the url character limit.

    public IHttpActionResult Put([FromUri] ViewModel data) { ... }

  • If you want to bind a simple type from the request body, you'll use [FromBody] in your action parameter.

    public IHttpActionResult Put([FromBody] string name) { ... }

as a side note, say you are making a PUT request (just a string) to update something. If you decide not to append it to the URL and pass as a complex type with just one property in the model, then the data parameter in jQuery ajax will look something like below. The object you pass to data parameter has only one property with empty property name.

var myName = 'ABC';
$.ajax({url:.., data: {'': myName}});

and your web api action will look something like below.

public IHttpActionResult Put([FromBody] string name){ ... }

This page explains it all.

WebDriver: check if an element exists?

This works for me every time:


Node Version Manager install - nvm command not found

All answers to this questions are useful. Especially the answer given by Travis helped me. For Mac OS X users I would like to provide some steps which will help them to work with the fresh installation of Node Version Manager a.k.a. nvm.

Installing & using nvm on Mac OS X

Here are the steps for fresh installation of nvm and using it without any issue:

  • Install homebrew from here.
  • Using homebrew install nvm

    brew update brew install nvm

  • Create .nvm directory at ~/.nvm location.

    mkdir ~/.nvm

  • Now if you don't have .bash_profile file setup for OS X terminal then please create a .bash_profile at the root level:

    nano ~/.bash_profile

  • Paste below code in the .bash_profile and press CTRL + O and press enter to save .bash_profile file. Press CTRL + X to exit from editor:

    export NVM_DIR=~/.nvm source $(brew --prefix nvm)/

  • Now either quite (CMD + Q) the terminal or run below command to load .bash_profile settings:

    source ~/.bash_profile

  • Now run nvm ls command to get the list of all installed nodejs versions.

Truncate all tables in a MySQL database in one command?

if using sql server 2005, there is a hidden stored procedure that allows you to execute a command or a set of commands against all tables inside a database. Here is how you would call TRUNCATE TABLE with this stored procedure:

EXEC [sp_MSforeachtable] @command1="TRUNCATE TABLE ?"

Here is a good article that elaborates further.

For MySql, however, you could use mysqldump and specify the --add-drop-tables and --no-data options to drop and create all tables ignoring the data. like this:

mysqldump -u[USERNAME] -p[PASSWORD] --add-drop-table --no-data [DATABASE]

mysqldump usage guide from dev.mysql

Using multiple case statements in select query

There are two ways to write case statements, you seem to be using a combination of the two

case a.updatedDate
    when 1760 then 'Entered on' + a.updatedDate
    when 1710 then 'Viewed on' + a.updatedDate
    else 'Last Updated on' + a.updateDate


    when a.updatedDate = 1760 then 'Entered on' + a.updatedDate
    when a.updatedDate = 1710 then 'Viewed on' + a.updatedDate
    else 'Last Updated on' + a.updateDate

are equivalent. They may not work because you may need to convert date types to varchars to append them to other varchars.

Correct way to pause a Python program

Print ("This is how you pause")


When to use Interface and Model in TypeScript / Angular

The Interface describes either a contract for a class or a new type. It is a pure Typescript element, so it doesn't affect Javascript.

A model, and namely a class, is an actual JS function which is being used to generate new objects.

I want to load JSON data from a URL and bind to the Interface/Model.

Go for a model, otherwise it will still be JSON in your Javascript.

Add querystring parameters to link_to

The API docs on link_to show some examples of adding querystrings to both named and oldstyle routes. Is this what you want?

link_to can also produce links with anchors or query strings:

link_to "Comment wall", profile_path(@profile, :anchor => "wall")
#=> <a href="/profiles/1#wall">Comment wall</a>

link_to "Ruby on Rails search", :controller => "searches", :query => "ruby on rails"
#=> <a href="/searches?query=ruby+on+rails">Ruby on Rails search</a>

link_to "Nonsense search", searches_path(:foo => "bar", :baz => "quux")
#=> <a href="/searches?foo=bar&amp;baz=quux">Nonsense search</a>