Programs & Examples On #Hibernate validator

Hibernate Validator is the reference implementation for JSR 380 - Bean Validation 2.0

javax.validation.ValidationException: HV000183: Unable to load 'javax.el.ExpressionFactory'

The Hibernate Validator requires — but does not include — an Expression Language (EL) implementation. Adding a dependency on one will will fix the issue.


This requirement is documented in the Getting started with Hibernate Validator documentation. In a Java EE environment, it would be provided by the container. In a standalone application such as yours, it needs to be provided.

Hibernate Validator also requires an implementation of the Unified Expression Language (JSR 341) for evaluating dynamic expressions in constraint violation messages.

When your application runs in a Java EE container such as WildFly, an EL implementation is already provided by the container.

In a Java SE environment, however, you have to add an implementation as dependency to your POM file. For instance, you can add the following dependency to use the JSR 341 reference implementation:


There are other EL implementations that can be used other than Glassfish. For instance, Spring Boot versions 2.2.x and earlier by default used embedded Tomcat (it's since switched to use the Jakarta EL reference implementation). That version of EL can be used as follows:


That said, in a Spring Boot project, typically one would use the spring-boot-starter-validation dependency rather than specifying the Hibernate validator & EL libraries directly. That dependency includes both hibernate-validator and the EL implementation.


Cross field validation with Hibernate Validator (JSR 303)

I have tried Alberthoven's example (hibernate-validator 4.0.2.GA) and i get an ValidationException: „Annotated methods must follow the JavaBeans naming convention. match() does not.“ too. After I renamed the method from „match“ to "isValid" it works.

public class Password {

    private String password;

    private String retypedPassword;

    public Password(String password, String retypedPassword) {
        this.password = password;
        this.retypedPassword = retypedPassword;

    @AssertTrue(message="password should match retyped password")
    private boolean isValid(){
        if (password == null) {
            return retypedPassword == null;
        } else {
            return password.equals(retypedPassword);

    public String getPassword() {
        return password;

    public String getRetypedPassword() {
        return retypedPassword;


How to set a cron job to run every 3 hours

Change Minute to be 0. That's it :)

Note: you can check your "crons" in


Double border with different color

You can use the border and box-shadow properties along with CSS pseudo elements to achieve a triple-border sort of effect. See the example below for an idea of how to create three borders at the bottom of a div:

.triple-border:after {_x000D_
    content: " ";_x000D_
    display: block;_x000D_
    width: 100%;_x000D_
    background: #FFE962;_x000D_
    height: 9px;_x000D_
    padding-bottom: 8px;_x000D_
    border-bottom: 9px solid #A3C662;_x000D_
    box-shadow: -2px 11px 0 -1px #34b6af;_x000D_
<div class="triple-border">Triple border bottom with multiple colours</div>

You'll have to play around with the values to get the alignment correct. However, you can also achieve more flexibility, e.g. 4 borders if you put some of the attributes in the proper element rather than the pseudo selector.

Retrieve only the queried element in an object array in MongoDB collection

You just need to run query

{"shapes.color": "red"}, 
{shapes: {$elemMatch: {color: "red"}}});

output of this query is

    "_id" : ObjectId("562e7c594c12942f08fe4192"),
    "shapes" : [ 
        {"shape" : "circle", "color" : "red"}

as you expected it'll gives the exact field from array that matches color:'red'.

mysql datetime comparison

...this is obviously performing a 'string' comparison

No - if the date/time format matches the supported format, MySQL performs implicit conversion to convert the value to a DATETIME, based on the column it is being compared to. Same thing happens with:

WHERE int_column = '1'

...where the string value of "1" is converted to an INTeger because int_column's data type is INT, not CHAR/VARCHAR/TEXT.

If you want to explicitly convert the string to a DATETIME, the STR_TO_DATE function would be the best choice:

WHERE expires_at <= STR_TO_DATE('2010-10-15 10:00:00', '%Y-%m-%d %H:%i:%s')

how to find host name from IP with out login to the host

Another NS lookup utility that can be used for reversed lookup is dig with the -x option:

$ dig -x

; <<>> DiG 9.9.2-P1 <<>> -x
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12770
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

; EDNS: version: 0, flags:; udp: 1460
;      IN      PTR

;; ANSWER SECTION: 42652 IN      PTR

;; Query time: 4 msec
;; WHEN: Fri Jan 25 21:23:40 2013
;; MSG SIZE  rcvd: 77


$ dig -x

; <<>> DiG 9.9.2-P1 <<>> -x
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11689
;; flags: qr aa ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;                IN      PTR

;; ANSWER SECTION: 10      IN      PTR     localhost.

;; Query time: 2 msec
;; WHEN: Fri Jan 25 21:23:49 2013
;; MSG SIZE  rcvd: 63

Quoting from the dig manpage:

Reverse lookups -- mapping addresses to names -- are simplified by the -x option. addr is an IPv4 address in dotted-decimal notation, or a colon-delimited IPv6 address. When this option is used, there is no need to provide the name, class and type arguments. dig automatically performs a lookup for a name like and sets the query type and class to PTR and IN respectively.

OS X Framework Library not loaded: 'Image not found'

The options above where not possible for me to include. I solved it by specifying the Runpath Search Path

This is on the 'Build Settings' tab. In the 'Linking' section. Change 'Runpath Search Paths' into $(inherited) @executable_path/Frameworks

Java - JPA - @Version annotation

Version used to ensure that only one update in a time. JPA provider will check the version, if the expected version already increase then someone else already update the entity so an exception will be thrown.

So updating entity value would be more secure, more optimist.

If the value changes frequent, then you might consider not to use version field. For an example "an entity that has counter field, that will increased everytime a web page accessed"

How to align a <div> to the middle (horizontally/width) of the page

If your center content is deep inside other divs then only margin can save you. Nothing else. I face it always when not using a framework like Bootstrap.

How to get first and last day of week in Oracle?

You could try this approach:

  1. Get the current date.

  2. Add the the number of years which is equal to the difference between the current date's year and the specified year.

  3. Subtract the number of days that is the last obtained date's week day's number (and it will give us the last day of some week).

  4. Add the number of weeks which is the difference between the last obtained date's week number and the specified week number, and that will yield the last day of the desired week.

  5. Subtract 6 days to obtain the first day.

How to create JNDI context in Spring Boot with Embedded Tomcat Container

Have you tried @Lazy loading the datasource? Because you're initialising your embedded Tomcat container within the Spring context, you have to delay the initialisation of your DataSource (until the JNDI vars have been setup).

N.B. I haven't had a chance to test this code yet!

public DataSource jndiDataSource() throws IllegalArgumentException, NamingException {
    JndiObjectFactoryBean bean = new JndiObjectFactoryBean();
    return (DataSource)bean.getObject();

You may also need to add the @Lazy annotation wherever the DataSource is being used. e.g.

private DataSource dataSource;

SMTP connect() failed PHPmailer - PHP

 $mail->SMTPOptions = array(
        'ssl' => array(
            'verify_peer' => false,
            'verify_peer_name' => false,
            'allow_self_signed' => true

How do I generate a random int number?

Sorry, OP indeed requires a random int value, but for the simple purpose to share knowledge if you want a random BigInteger value you can use following statement:

BigInteger randomVal = BigInteger.Abs(BigInteger.Parse(Guid.NewGuid().ToString().Replace("-",""), NumberStyles.AllowHexSpecifier));

Styles.Render in MVC4

Set this to False on your web.config

<compilation debug="false" targetFramework="4.6.1" />

What is the difference between join and merge in Pandas?

One of the difference is that merge is creating a new index, and join is keeping the left side index. It can have a big consequence on your later transformations if you wrongly assume that your index isn't changed with merge.

For example:

import pandas as pd

df1 = pd.DataFrame({'org_index': [101, 102, 103, 104],
                    'date': [201801, 201801, 201802, 201802],
                    'val': [1, 2, 3, 4]}, index=[101, 102, 103, 104])

       date  org_index  val
101  201801        101    1
102  201801        102    2
103  201802        103    3
104  201802        104    4


df2 = pd.DataFrame({'date': [201801, 201802], 'dateval': ['A', 'B']}).set_index('date')

201801       A
201802       B


df1.merge(df2, on='date')

     date  org_index  val dateval
0  201801        101    1       A
1  201801        102    2       A
2  201802        103    3       B
3  201802        104    4       B


df1.join(df2, on='date')
       date  org_index  val dateval
101  201801        101    1       A
102  201801        102    2       A
103  201802        103    3       B
104  201802        104    4       B

Jinja2 template variable if None Object set a default value

As another solution (kind of similar to some previous ones):

{{ ( p is defined and p.User is defined and p.User['first_name'] ) |default("NONE", True) }}

Note the last variable (p.User['first_name']) does not have the if defined test after it.

Iterate over object keys in node.js

For simple iteration of key/values, sometimes libraries like underscorejs can be your friend.

const _ = require('underscore');

_.each(a, function (value, key) {
    // handle

just for reference

less than 10 add 0 to number

Here is Genaric function for add any number of leading zeros for making any size of numeric string.

function add_zero(your_number, length) {
    var num = '' + your_number;
    while (num.length < length) {
        num = '0' + num;
    return num;

Ubuntu apt-get unable to fetch packages

I tried using :

sudo do-release-upgrade

and then use :

sudo apt-get update

after that you will be able to install any packages.

If this did not worked for you try to change the network conf in apt.conf

sudo: docker-compose: command not found

If docker-compose is installed for your user but not installed for root user and if you need to run it only once and forget about it afterwords perform the next actions:

  • Find out path to docker-compose:

      which docker-compose
  • Run the command specifying full path to docker-compose from the previous command, eg:

      sudo /home/your-user/your-path-to-compose/docker-compose up

Using Axios GET with Authorization Header in React-Native App

Could not get this to work until I put Authorization in single quotes:

axios.get(URL, { headers: { 'Authorization': AuthStr } })

Trying to SSH into an Amazon Ec2 instance - permission error

You are likely using the wrong username to login:

  • most Ubuntu images have a user ubuntu
  • Amazon's AMI is ec2-user
  • most Debian images have either root or admin

To login, you need to adjust your ssh command:

ssh -l USERNAME_HERE -i .ssh/yourkey.pem public-ec2-host


How to customize the background color of a UITableViewCell?

The best approach I've found so far is to set a background view of the cell and clear background of cell subviews. Of course, this looks nice on tables with indexed style only, no matter with or without accessories.

Here is a sample where cell's background is panted yellow:

UIView* backgroundView = [ [ [ UIView alloc ] initWithFrame:CGRectZero ] autorelease ];
backgroundView.backgroundColor = [ UIColor yellowColor ];
cell.backgroundView = backgroundView;
for ( UIView* view in cell.contentView.subviews ) 
    view.backgroundColor = [ UIColor clearColor ];

What exactly is the function of Application.CutCopyMode property in Excel

Normally, When you copy a cell you will find the below statement written down in the status bar (in the bottom of your sheet)

"Select destination and Press Enter or Choose Paste"

Then you press whether Enter or choose paste to paste the value of the cell.

If you didn't press Esc afterwards you will be able to paste the value of the cell several times

Application.CutCopyMode = False does the same like the Esc button, if you removed it from your code you will find that you are able to paste the cell value several times again.

And if you closed the Excel without pressing Esc you will get the warning 'There is a large amount of information on the Clipboard....'

Scrollbar without fixed height/Dynamic height with scrollbar

You will have to specify a fixed height, you cannot use 100% because there is nothing for this to be compared to, as in height=100% of what?

Edited fiddle:

PYODBC--Data source name not found and no default driver specified

Create a DSN something like this (ASEDEV) for your connection and try to use DSN instead of DRIVER like below:

enter code here
import pyodbc
cnxn = pyodbc.connect('DSN=ASEDEV;User ID=sa;Password=sybase123')
mycur = cnxn.cursor()
mycur.execute("select * from master..sysdatabases")
row = mycur.fetchone()
while row:
    row = mycur.fetchone()`

How to run multiple DOS commands in parallel?

You can execute commands in parallel with start like this:

start "" ping myserver
start "" nslookup myserver
start "" morecommands

They will each start in their own command prompt and allow you to run multiple commands at the same time from one batch file.

Hope this helps!

How to insert data to MySQL having auto incremented primary key?

The default keyword works for me:

mysql> insert into user_table (user_id, ip, partial_ip, source, user_edit_date, username) values 
(default, '', null, 'user signup page', now(), 'newUser');
Query OK, 1 row affected (0.00 sec)

I'm running mysql --version 5.1.66:

mysql  Ver 14.14 Distrib **5.1.66**, for debian-linux-gnu (x86_64) using readline 6.1

How to catch exception correctly from http.request()?

in the latest version of angular4 use

import { Observable } from 'rxjs/Rx'

it will import all the required things.

How can I perform a short delay in C# without using sleep?

You can probably use timers :

Timers can provide you a precision up to 1 millisecond. Depending on the tick interval an event will be generated. Do your stuff inside the tick event.

Is null reference possible?

clang++ 3.5 even warns on it:

/tmp/a.C:3:7: warning: reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to
      always evaluate to false [-Wtautological-undefined-compare]
if( & nullReference == 0 ) // null reference
      ^~~~~~~~~~~~~    ~
1 warning generated.

How to set the default value of an attribute on a Laravel model

You can set Default attribute in Model also>

protected $attributes = [
        'status' => self::STATUS_UNCONFIRMED,
        'role_id' => self::ROLE_PUBLISHER,

You can find the details in these links

1.) How to set a default attribute value for a Laravel / Eloquent model?


You can also Use Accessors & Mutators for this You can find the details in the Laravel documentation 1.)


3.) Universal accessors and mutators in Laravel 4

How do I get the parent directory in Python?

>>> import os
>>> os.path.basename(os.path.dirname(<your_path>))

For example in Ubuntu:

>>> my_path = '/home/user/documents'
>>> os.path.basename(os.path.dirname(my_path))
# Output: 'user'

For example in Windows:

>>> my_path = 'C:\WINDOWS\system32'
>>> os.path.basename(os.path.dirname(my_path))
# Output: 'WINDOWS'

Both examples tried in Python 2.7

SQL Server: Make all UPPER case to Proper Case/Title Case

Is it too late to go back and get the un-uppercased data?

The von Neumann's, McCain's, DeGuzman's, and the Johnson-Smith's of your client base may not like the result of your processing...

Also, I'm guessing that this is intended to be a one-time upgrade of the data? It might be easier to export, filter/modify, and re-import the corrected names into the db, and then you can use non-SQL approaches to name fixing...

What is a LAMP stack?

Lamp stack stands for Linux Apache Mysql PHP

there is also Mean Stack MongoDB ExpressJS AngularJS NodeJS

How to keep console window open

There are two ways I know of

1) Console.ReadLine() at the end of the program. Disadvantage, you have to change your code and have to remember to take it out

2) Run outside of the debugger CONTROL-F5 this opens a console window outside of visual studio and that window won't close when finished. Advantage, you don't have to change your code. Disadvantage, if there is an exception, it won't drop into the debugger (however when you do get exceptions, you can simply just rerun it in the debugger)

Build Android Studio app via command line

Only for MAC Users

Extending Vji's answer.

Step by step procedure:

  1. Open Terminal
  2. Change your directory to your Project(cd PathOfYourProject)
  3. Copy and paste this command and hit enter:

    chmod +x gradlew
  4. As Vji suggested:

    ./gradlew task-name


Allow Access-Control-Allow-Origin header using HTML5 fetch API

Solution to resolve issue in Local env's

I had my front-end code running in http://localhost:3000 and my API(Backend code) running at http://localhost:5000

Was using fetch API to call the API. Initially, it was throwing "cors" error. Then added this below code in my Backend API code, allowing origin and header from anywhere.

let allowCrossDomain = function(req, res, next) {
  res.header('Access-Control-Allow-Origin', "*");
  res.header('Access-Control-Allow-Headers', "*");

However you must restrict origins in case of other environments like stage, prod.

Strictly NO for higher environments.

Checking if an input field is required using jQuery

$('form#register input[required]')

It will only return inputs which have required attribute.

Jquery Change Height based on Browser Size/Resize

Pay attention, there is a bug with Jquery 1.8.0, $(window).height() returns the all document height !

The import org.junit cannot be resolved

you can easily search for a line like "@Test" and then use the quickfix "add junit 4 library to the build path" at this line. i think this is faster than adding junit manually to the project.

Differences between git pull origin master & git pull origin/master

git pull origin master will pull changes from the origin remote, master branch and merge them to the local checked-out branch.

git pull origin/master will pull changes from the locally stored branch origin/master and merge that to the local checked-out branch. The origin/master branch is essentially a "cached copy" of what was last pulled from origin, which is why it's called a remote branch in git parlance. This might be somewhat confusing.

You can see what branches are available with git branch and git branch -r to see the "remote branches".

How to navigate to a directory in C:\ with Cygwin?

Something that is worth mentioning here is that Cygwin's cygpath, still does not handle spaced Windows paths properly, especially in Bash scripts running under Cygwin. The trick is to understand how Cygwin interprets quotes in Bash scripts.

The following does not work:

TBDIR="/cygdrive/c/Program\ Files\ \(x86\)/MyDir/"

if [ -d "${TBDIR}" ]; then 
    echo "Found MyDir directory at: ${TBDIR}"
    cd "$TBDIR"
    echo "MyDir program directory not found!"
    echo "Wrong DIR path: ${TBDIR}"
    exit 1

But this does work:

# Cygwin-ism: No quotes!
TBDIR=/cygdrive/c/Program\ Files\ \(x86\)/MyDir/

if [ -d "${TBDIR}" ]; then 

As far as I know, there is currently no known workaround using cygpath, that can properly handle spaces in the bash scripting context but you can use quotes in your scripts.

Assignment inside lambda expression in Python

You can use a bind function to use a pseudo multi-statement lambda. Then you can use a wrapper class for a Flag to enable assignment.

bind = lambda x, f=(lambda y: y): f(x)

class Flag(object):
    def __init__(self, value):
        self.value = value

    def set(self, value):
        self.value = value
        return value

input = [Object(name=""), Object(name="fake_name"), Object(name="")]
flag = Flag(True)
output = filter(
            lambda o: (
                bind(flag.value, lambda orig_flag_value:
                bind(flag.set(flag.value and bool(, lambda _:
                bind(orig_flag_value or bool(,

Delete all nodes and relationships in neo4j 1.8

It will do the trick..

Match (n)-[r]-()
Delete n,r;

How to make node.js require absolute? (instead of relative)

I use process.cwd() in my projects. For example:

var Foo = require(process.cwd() + '/common/foo.js');

It might be worth noting that this will result in requireing an absolute path, though I have yet to run into issues with this.

How To have Dynamic SQL in MySQL Stored Procedure

After 5.0.13, in stored procedures, you can use dynamic SQL:

delimiter // 
CREATE PROCEDURE dynamic(IN tbl CHAR(64), IN col CHAR(64))
    SET @s = CONCAT('SELECT ',col,' FROM ',tbl );
    PREPARE stmt FROM @s;
    EXECUTE stmt;
delimiter ;

Dynamic SQL does not work in functions or triggers. See the MySQL documentation for more uses.

Can I get Unix's pthread.h to compile in Windows?

As @Ninefingers mentioned, pthreads are unix-only. Posix only, really.

That said, Microsoft does have a library that duplicates pthreads:

Microsoft Windows Services for UNIX Version 3.5

Library Download

How to set a value of a variable inside a template code?

You can use the with template tag.

{% with name="World" %}     
<div>Hello {{name}}!</div>
{% endwith %}

How to prevent null values inside a Map and null fields inside a bean from getting serialized through Jackson

Answer seems to be a little old, What I did was to use this mapper to convert a MAP

      ObjectMapper mapper = new ObjectMapper().configure(SerializationConfig.Feature.WRITE_NULL_MAP_VALUES, false);

a simple Map:

          Map<String, Object> user = new HashMap<String,Object>();
            user.put( "id",  teklif.getAccount().getId() );
            user.put( "fname", teklif.getAccount().getFname());
            user.put( "lname", teklif.getAccount().getLname());
            user.put( "email", teklif.getAccount().getEmail());
            user.put( "test", null);

Use it like this for example:

      String json = mapper.writeValueAsString(user);

Heap space out of memory

No. The heap is cleared by the garbage collector whenever it feels like it. You can ask it to run (with System.gc()) but it is not guaranteed to run.

First try increasing the memory by setting -Xmx256m

What is the difference between application server and web server?

IMO, it's mostly about separating concerns.

From a purely technical point of view, you can do everything (web content + business logic) in a single web server. If you'd do that, then the information would be embedded inside requested the HTML content. What would be the impact?

For example, imagine you have 2 different apps which renders entirely different HTML content on the browser. If you would separate the business logic into an app-server than you could provide different web-servers looking up the same data in the app-server via scripts. However, If you wouldn't separate the logic and keep it in the web-server, whenever you change your business model, you would end up changing it in every single web-server you have which would take more time, be less reliable and error-prone.

How to resolve the "EVP_DecryptFInal_ex: bad decrypt" during file decryption

I think the Key and IV used for encryption using command line and decryption using your program are not same.

Please note that when you use the "-k" (different from "-K"), the input given is considered as a password from which the key is derived. Generally in this case, there is no need for the "-iv" option as both key and password will be derived from the input given with "-k" option.

It is not clear from your question, how you are ensuring that the Key and IV are same between encryption and decryption.

In my suggestion, better use "-K" and "-iv" option to explicitly specify the Key and IV during encryption and use the same for decryption. If you need to use "-k", then use the "-p" option to print the key and iv used for encryption and use the same in your decryption program.

More details can be obtained at

Remove a JSON attribute

The selected answer would work for as long as you know the key itself that you want to delete but if it should be truly dynamic you would need to use the [] notation instead of the dot notation.

For example:

var keyToDelete = "key1";
var myObj = {"test": {"key1": "value", "key2": "value"}}

//that will not work.
delete myObj.test.keyToDelete 

instead you would need to use:

delete myObj.test[keyToDelete];

Substitute the dot notation with [] notation for those values that you want evaluated before being deleted.

Put buttons at bottom of screen with LinearLayout?

first create file name it as footer.xml put this code inside it.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
    android:background="@drawable/actionbar_dark_background_tile" >
        android:src="@drawable/overlay" />
        android:src="@drawable/notcolor" />
        android:src="@drawable/colored" />
        android:layout_weight=".14" />


then create header.xml and put this code inside it.:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
    android:background="@drawable/actionbar_dark_background_tile" >

        android:src="@drawable/share" />

        android:src="@drawable/save" />

        android:src="@drawable/set" />

        android:src="@drawable/light" />

        android:src="@drawable/ic_menu_rotate" />

        android:src="@drawable/stock" />


and then in your main_activity.xml and put this code inside it :-

<RelativeLayout xmlns:android=""
android:background="@drawable/background" >

    android:layout_alignParentBottom="true" >

        layout="@layout/footer" >
    <include layout="@layout/header"

happy coding :)

How can I use different certificates on specific connections?

I read through LOTS of places online to solve this thing. This is the code I wrote to make it work:

ByteArrayInputStream derInputStream = new ByteArrayInputStream(app.certificateString.getBytes());
CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
X509Certificate cert = (X509Certificate) certificateFactory.generateCertificate(derInputStream);
String alias = "alias";//cert.getSubjectX500Principal().getName();

KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType());
trustStore.setCertificateEntry(alias, cert);
KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
kmf.init(trustStore, null);
KeyManager[] keyManagers = kmf.getKeyManagers();

TrustManagerFactory tmf = TrustManagerFactory.getInstance("X509");
TrustManager[] trustManagers = tmf.getTrustManagers();

SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(keyManagers, trustManagers, null);
URL url = new URL(someURL);
conn = (HttpsURLConnection) url.openConnection();

app.certificateString is a String that contains the Certificate, for example:

static public String certificateString=
        "-----BEGIN CERTIFICATE-----\n" +
        ... a bunch of characters...
        "5126sfeEJMRV4Fl2E5W1gDHoOd6V==\n" +
        "-----END CERTIFICATE-----";

I have tested that you can put any characters in the certificate string, if it is self signed, as long as you keep the exact structure above. I obtained the certificate string with my laptop's Terminal command line.

How to mark-up phone numbers?

Mobile Safari (iPhone & iPod Touch) use the tel: scheme.

How do I dial a phone number from a webpage on iPhone?

Android, How can I Convert String to Date?

It could be a good idea to be careful with the Locale upon which c.getTime().toString(); depends.

One idea is to store the time in seconds (e.g. UNIX time). As an int you can easily compare it, and then you just convert it to string when displaying it to the user.

AWS ssh access 'Permission denied (publickey)' issue

Its ec2-user for Amazon Linux AMI's and ubuntu for Ubuntu images. Also, RHEL 6.4 and later ec2-user RHEL 6.3 and earlier root Fedora ec2-user Centos root

Jackson JSON: get node name from json-tree

fields() and fieldNames() both were not working for me. And I had to spend quite sometime to find a way to iterate over the keys. There are two ways by which it can be done.

One is by converting it into a map (takes up more space):

ObjectMapper mapper = new ObjectMapper();
Map<String, Object> result = mapper.convertValue(jsonNode, Map.class);
for (String key : result.keySet())
        //code here

Another, by using a String iterator:

Iterator<String> it = jsonNode.getFieldNames();
while (it.hasNext())
    String key =;
    if (key.equals(foo))
         //code here

How do I express "if value is not empty" in the VBA language?

I am not sure if this is what you are looking for

if var<>"" then


if isempty(thisworkbook.sheets("sheet1").range("a1").value)= false then

the ISEMPTY function can be used as well

Converting an OpenCV Image to Black and White

For those doing video I cobbled the following based on @tsh :

import cv2 as cv
import numpy as np

def nothing(x):pass

cap = cv.VideoCapture(0)
cv.namedWindow('videoUI', cv.WINDOW_NORMAL)

    ret, frame =
    vid_gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
    thresh = cv.getTrackbarPos('T','videoUI');
    vid_bw = cv.threshold(vid_gray, thresh, 255, cv.THRESH_BINARY)[1]


    if cv.waitKey(1) & 0xFF == ord('q'):


Results in:

enter image description here

Get records of current month

Try this query:

FROM table 

Can enums be subclassed to add new elements?

enum A {a,b,c}
enum B extends A {d}
/*B is {a,b,c,d}*/

can be written as:

public enum All {
    a       (ClassGroup.A,ClassGroup.B),
    b       (ClassGroup.A,ClassGroup.B),
    c       (ClassGroup.A,ClassGroup.B),
    d       (ClassGroup.B) 
  • ClassGroup.B.getMembers() contains {a,b,c,d}

How it can be useful: Let say we want something like: We have events and we are using enums. Those enums can be grouped by similar processing. If we have operation with many elements, then some events starts operation, some are just step and other end the operation. To gather such operation and avoid long switch case we can group them as in example and use:

if( makeNewOperationObject()..
if( makeSomeSeriousChanges()..
if( closeTransactionOrSomething()..


public enum AtmOperationStatus {
STARTED_BY_SERVER       (State_StatusGroup.START),
SUCCESS             (State_StatusGroup.FINISH),
FAIL_TOKEN_TIMEOUT      (State_StatusGroup.FAIL, 
FAIL_NOT_COMPLETE       (State_StatusGroup.FAIL,
FAIL_UNKNOWN            (State_StatusGroup.FAIL,

private AtmOperationStatus(StatusGroupInterface ... pList){
    for (StatusGroupInterface group : pList){
public boolean is(StatusGroupInterface with){
    for (AtmOperationStatus eT : with.getMembers()){
        if( eT .equals(this))   return true;
    return false;
// Each group must implement this interface
private interface StatusGroupInterface{
    EnumSet<AtmOperationStatus> getMembers();
    void addMember(AtmOperationStatus pE);
public enum State_StatusGroup implements StatusGroupInterface{

    private List<AtmOperationStatus> members = new LinkedList<AtmOperationStatus>();

    public EnumSet<AtmOperationStatus> getMembers() {
        return EnumSet.copyOf(members);

    public void addMember(AtmOperationStatus pE) {
    static { // forcing initiation of dependent enum
        try {
        } catch (ClassNotFoundException ex) { 
            throw new RuntimeException("Class AtmEventType not found", ex); 
//Some use of upper code:
if (p.getStatus().is(AtmOperationStatus.State_StatusGroup.FINISH)) {
    //do something
}else if (p.getStatus().is(AtmOperationStatus.State_StatusGroup.START)) {
    //do something      

Add some more advanced:

public enum AtmEventType {

USER_DEPOSIT        (Status_EventsGroup.WITH_STATUS,

At above if we have some fail ( then iterating by previous events we can easily check if we must revert money transfer by:

if( rollBack()..

It can be useful for:

  1. including explicite meta-data about processing logic, less to remember
  2. implementing some of multi-inheritance
  3. we don't want to use class structures, ex. for sending short status messages

How to stop process from .BAT file?

taskkill /F /IM notepad.exe this is the best way to kill the task from task manager.

jQuery iframe load() event?

Along the lines of Tim Down's answer but leveraging jQuery (mentioned by the OP) and loosely coupling the containing page and the iframe, you could do the following:

In the iframe:

    $(function() {
        var w = window;
        if (w.frameElement != null
                && w.frameElement.nodeName === "IFRAME"
                && w.parent.jQuery) {

In the containing page:

    function myHandler() {
        alert('iframe (almost) loaded');
    $(document).on('iframeready', myHandler);

The iframe fires an event on the (potentially existing) parent window's document - please beware that the parent document needs a jQuery instance of itself for this to work. Then, in the parent window you attach a handler to react to that event.

This solution has the advantage of not breaking when the containing page does not contain the expected load handler. More generally speaking, it shouldn't be the concern of the iframe to know its surrounding environment.

Please note, that we're leveraging the DOM ready event to fire the event - which should be suitable for most use cases. If it's not, simply attach the event trigger line to the window's load event like so:

$(window).on('load', function() { ... });

Listing all the folders subfolders and files in a directory using php

A very simple way to show folder structure makes use of RecursiveTreeIterator class (PHP 5 >= 5.3.0, PHP 7) and generates an ASCII graphic tree.

$it = new RecursiveTreeIterator(new RecursiveDirectoryIterator("/path/to/dir", RecursiveDirectoryIterator::SKIP_DOTS));
foreach($it as $path) {
  echo $path."<br>";

There is also some control over the ASCII representation of the tree by changing the prefixes using RecursiveTreeIterator::setPrefixPart, for example $it->setPrefixPart(RecursiveTreeIterator::PREFIX_LEFT, "|");

kubectl apply vs kubectl create?

Just to give a more straight forward answer, from my understanding:

apply - makes incremental changes to an existing object
create - creates a whole new object (previously non-existing / deleted)

Taking this from a DigitalOcean article which was linked by Kubernetes website:

We use apply instead of create here so that in the future we can incrementally apply changes to the Ingress Controller objects instead of completely overwriting them.

Given a URL to a text file, what is the simplest way to read the contents of the text file?

Just updating here solution suggested by @ken-kinder for Python 2 to work for Python 3:

import urllib

Ajax Upload image


<div class="rCol"> 
     <div id ="prv" style="height:auto; width:auto; float:left; margin-bottom: 28px; margin-left: 200px;"></div>
    <div class="rCol" style="clear:both;">

    <label > Upload Photo : </label> 
    <input type="file" id="file" name='file' onChange=" return submitForm();">
    <input type="hidden" id="filecount" value='0'>

Here is Ajax Code:

function submitForm() {

    var fcnt = $('#filecount').val();
    var fname = $('#filename').val();
    var imgclean = $('#file');
    data = new FormData();
    data.append('file', $('#file')[0].files[0]);

    var imgname  =  $('input[type=file]').val();
     var size  =  $('#file')[0].files[0].size;

    var ext =  imgname.substr( (imgname.lastIndexOf('.') +1) );
    if(ext=='jpg' || ext=='jpeg' || ext=='png' || ext=='gif' || ext=='PNG' || ext=='JPG' || ext=='JPEG')
      url: "<?php echo base_url() ?>/upload.php",
      type: "POST",
      data: data,
      enctype: 'multipart/form-data',
      processData: false,  // tell jQuery not to process the data
      contentType: false   // tell jQuery not to set contentType
    }).done(function(data) {
       if(data!='FILE_SIZE_ERROR' || data!='FILE_TYPE_ERROR' )
        fcnt = parseInt(fcnt)+1;
        var img = '<div class="dialog" id ="img_'+fcnt+'" ><img src="<?php echo base_url() ?>/local_cdn/'+data+'"><a href="#" id="rmv_'+fcnt+'" onclick="return removeit('+fcnt+')" class="close-classic"></a></div><input type="hidden" id="name_'+fcnt+'" value="'+data+'">';
          fname = fname+','+data;
          fname = data;
          imgclean.replaceWith( imgclean = imgclean.clone( true ) );
         imgclean.replaceWith( imgclean = imgclean.clone( true ) );
         alert('SORRY SIZE AND TYPE ISSUE');

    return false;
  }//end size
      imgclean.replaceWith( imgclean = imgclean.clone( true ) );//Its for reset the value of file type
    alert('Sorry File size exceeding from 1 Mb');
  }//end FILETYPE
     imgclean.replaceWith( imgclean = imgclean.clone( true ) );
    alert('Sorry Only you can uplaod JPEG|JPG|PNG|GIF file type ');
  }//end filecount
  {    imgclean.replaceWith( imgclean = imgclean.clone( true ) );
     alert('You Can not Upload more than 6 Photos');

Here is PHP code :

$filetype = array('jpeg','jpg','png','gif','PNG','JPEG','JPG');
   foreach ($_FILES as $key )

          $name =time().$key['name'];

          $file_ext =  pathinfo($name, PATHINFO_EXTENSION);
          if(in_array(strtolower($file_ext), $filetype))

             echo $name;

               echo "FILE_SIZE_ERROR";
            echo "FILE_TYPE_ERROR";
        }// Its simple code.Its not with proper validation.

Here upload and preview part done.Now if you want to delete and remove image from page and folder both then code is here for deletion. Ajax Part:

function removeit (arg) {
       var id  = arg;
       // GET FILE VALUE
       var fname = $('#filename').val();
       var fcnt = $('#filecount').val();
        // GET FILE VALUE


        var dname  =  $('#name_'+id).val();
        fcnt = parseInt(fcnt)-1;
        var fname = fname.replace(dname, "");
        var fname = fname.replace(",,", "");
          url: 'delete.php',
          type: 'POST',

Here is PHP part(delete.php):


     echo "Success";
     echo "Failed";

Appending a byte[] to the end of another byte[]

Using System.arraycopy(), something like the following should work:

// create a destination array that is the size of the two arrays
byte[] destination = new byte[ciphertext.length + mac.length];

// copy ciphertext into start of destination (from pos 0, copy ciphertext.length bytes)
System.arraycopy(ciphertext, 0, destination, 0, ciphertext.length);

// copy mac into end of destination (from pos ciphertext.length, copy mac.length bytes)
System.arraycopy(mac, 0, destination, ciphertext.length, mac.length);

How to make google spreadsheet refresh itself every 1 minute?

GOOGLEFINANCE can have a 20 minutes delay, so refreshing every minute would not really help.

Instead of GOOGLEFINANCE you can use different source. I'm using this RealTime stock prices(I tried a couple but this is the easiest by-far to implement. They have API that retuen JSON { Name: CurrentPrice }

Here's a little script you can use in Google Sheets(Tools->Script Editor)

function GetStocksPrice() {      
   var url = ' 
   var response = UrlFetchApp.fetch(url);

   // convert json string to json object
   var jsonSignal = JSON.parse(response);    

  // define an array of all the object keys
  var headerRow = Object.keys(jsonSignal);
  // define an array of all the object values
  var values ={ return jsonSignal[key]});   
  var data = values[0];

  // get sheet by ID -  
  // you can get the sheet unqiue ID from the your current sheet url
  var jsonSheet = SpreadsheetApp.openById("Your Sheet UniqueID");  
  //var name = jsonSheet.getName();

  var sheet = jsonSheet.getSheetByName('Sheet1'); 

  // the column to put the data in -> Y
  var letter = "F";

  // start from line 
  var index = 4;
  data.forEach(function( row, index2 ) { 

     var keys = Object.keys(row);
     var value2 = row[keys[1]];            

     // set value loction
     var cellXY = letter +  index;      
     index = index + 1;    

Now you need to add a trigger that will execute every minute.

  1. Go to Project Triggers -> click on the Watch icon next to the Save icon
  2. Add Trigger
  3. In -> Choose which function to run -> GetStocksPrice
  4. In -> Select event source -> Time-driven
  5. In -> Select type of time based trigger -> Minutes timer
  6. In -> Select minute interval -> Every minute

And your set :)

The PowerShell -and conditional operator

You can simplify it to

if ($user_sam -and $user_case) {

because empty strings coerce to $false (and so does $null, for that matter).

Truncate a string straight JavaScript

in case you want to truncate by word.

function limit(str, limit, end) {_x000D_
      limit = (limit)? limit : 100;_x000D_
      end = (end)? end : '...';_x000D_
      str = str.split(' ');_x000D_
      if (str.length > limit) {_x000D_
        var cutTolimit = str.slice(0, limit);_x000D_
        return cutTolimit.join(' ') + ' ' + end;_x000D_
      return str.join(' ');_x000D_
    var limit = limit('ILorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus metus magna, maximus a dictum et, hendrerit ac ligula. Vestibulum massa sapien, venenatis et massa vel, commodo elementum turpis. Nullam cursus, enim in semper luctus, odio turpis dictum lectus', 20);_x000D_

Visual C++ executable and missing MSVCR100d.dll

Usually the application that misses the .dll indicates what version you need – if one does not work, simply download the Microsoft visual C++ 2010 x86 or x64 from this link:

For 32 bit OS:Here

For 64 bit OS:Here

Rotate axis text in python matplotlib

The simplest solution is to use:


but also

# Tweak spacing to prevent clipping of tick-labels

e.g for dates I used rotation=45 and bottom=0.20 but you can do some test for your data

convert string to date in sql server

I had a similar situation. Here's what I was able to do to get a date range in a "where" clause (a modification of marc_s's answer):

where cast(replace(foo.TestDate, '-', '') as datetime) 
      between cast('20110901' as datetime) and
              cast('20510531' as datetime)

Hope that helps...

Turning multi-line string into single comma-separated

Well the hardest part probably is selecting the second "column" since I wouldn't know of an easy way to treat multiple spaces as one. For the rest it's easy. Use bash substitutions.

# cat bla.txt
something1:    +12.0   (some unnecessary trailing data (this must go))
something2:    +15.5   (some more unnecessary trailing data)
something4:    +9.0   (some other unnecessary data)
something1:    +13.5  (blah blah blah)

# cat
for i in $(cat bla.txt); do
  i=$(echo "$i" | awk '{print $2}')
  u="${u:+$u, }$i"
echo "$u"

# bash ./
+12.0, +15.5, +9.0, +13.5

Initialize a byte array to a certain value, other than the default null?

This is a faster version of the code from the post marked as the answer.

All of the benchmarks that I have performed show that a simple for loop that only contains something like an array fill is typically twice as fast if it is decrementing versus if it is incrementing.

Also, the array Length property is already passed as the parameter so it doesn't need to be retrieved from the array properties. It should also be pre-calculated and assigned to a local variable. Loop bounds calculations that involve a property accessor will re-compute the value of the bounds before each iteration of the loop.

public static byte[] CreateSpecialByteArray(int length)
    byte[] array = new byte[length];

    int len = length - 1;

    for (int i = len; i >= 0; i--)
        array[i] = 0x20;

    return array;

Show/Hide Table Rows using Javascript classes

AngularJS directives ng-show, ng-hide allows to display and hide a row:

   <tr ng-show="rw.isExpanded">

A row will be visible when rw.isExpanded == true and hidden when rw.isExpanded == false. ng-hide performs the same task but requires inverse condition.

WooCommerce - get category for product page

$product->get_categories() is deprecated since version 3.0! Use wc_get_product_category_list instead.

how to hide the content of the div in css

Hiding through CSS is achieved by using either the "visibility" or the "display" attributes. Though both achieve similar results, it's useful to know the differences.

If you only want to hide the element but retain the space occupied by it, you should use:

#mybox:hover {
   visibility: hidden;

If you want to hide the element and remove the space occupied by it, so that other elements can take its space, then you should use:

#mybox:hover {
   display: none;

Also remember that IE6 and below do not respond to :hover for anything except A tags. In which case, you'll need some Javascript to change the classname:

document.getElementById('mybox').className = 'hide';

and define the "hide" class in CSS:

.hide { display: none; }

jquery to loop through table rows and cells, where checkob is checked, concatenate


I've updated your demo:

Also, I've changed two ^= to *=. See

And note the :checked selector. See

function createcodes() {

    //run through each row
    $('.authors-list tr').each(function (i, row) {

        // reference all the stuff you need first
        var $row = $(row),
            $family = $row.find('input[name*="family"]'),
            $grade = $row.find('input[name*="grade"]'),
            $checkedBoxes = $row.find('input:checked');

        $checkedBoxes.each(function (i, checkbox) {
            // assuming you layout the elements this way, 
            // we'll take advantage of .next()
            var $checkbox = $(checkbox),
                $line = $,
                $size = $;

                $family.val() + ' ' + $size.val() + ', ' + $grade.val()



Silent installation of a MSI package

The proper way to install an MSI silently is via the msiexec.exe command line as follows:

msiexec.exe /i c:\setup.msi /QN /L*V "C:\Temp\msilog.log"

Quick explanation:

 /L*V "C:\Temp\msilog.log"= verbose logging
 /QN = run completely silently
 /i = run install sequence 

There is a much more comprehensive answer here: Batch script to install MSI. This answer provides details on the msiexec.exe command line options and a description of how to find the "public properties" that you can set on the command line at install time. These properties are generally different for each MSI.

Check for special characters in string

You can try this:

regex = [\W_]

It will definitely help you.

How do I print colored output to the terminal in Python?

There are a few libraries that help out here. For cmdline tools I sometimes use colorama.


from colorama import init, Fore, Back, Style

def cprint(msg, foreground = "black", background = "white"):
    fground = foreground.upper()
    bground = background.upper()
    style = getattr(Fore, fground) + getattr(Back, bground)
    print(style + msg + Style.RESET_ALL)

cprint("colorful output, wohoo", "red", "black")

But instead of using strings, you might want to use an enum and/or add a few checks. Not the prettiest solution, but works on osx/linux and windows and is easy to use.

Other threads about this topic and cross-platform support: e.g. here.

Video format or MIME type is not supported


I was losing my mind over this one. Reset firefox, tried safe mode, removed plugins, debugged using developers tools. All were to no avail and didn't get me any further with getting my online videos back to normal viewing condition. This however did the trick perfectly.

Within Firefox or whatever flavor of Firefox you have(CyberFox being my favorite choice here), simply browse to

VERIFY FIRST that the website detected you're using FireFox and has set your download for the flash player to be for Firefox.

Don't just click download. PLEASE PLEASE PLEASE SAVE YOURSELF the migraine and ALWAYS make sure that the middle section labeled "Optional offer:" is absolutely NOT CHECKED, it will be checked by default so always UNCHECK it before proceeding to download.

After it's finished downloading, close out of Firefox. Run the downloaded setup file As Administrator. It takes only a few seconds or so to complete, so after it's done, open up Firefox again and try viewing anything that was previously throwing this error. Should be back to normal now.


Kill a Process by Looking up the Port being used by it from a .BAT

Here's a command to get you started:

FOR /F "tokens=4 delims= " %%P IN ('netstat -a -n -o ^| findstr :8080') DO @ECHO TaskKill.exe /PID %%P

When you're confident in your batch file, remove @ECHO.

FOR /F "tokens=4 delims= " %%P IN ('netstat -a -n -o ^| findstr :8080') DO TaskKill.exe /PID %%P

Note that you might need to change this slightly for different OS's. For example, on Windows 7 you might need tokens=5 instead of tokens=4.

How this works

FOR /F ... %variable IN ('command') DO otherCommand %variable...

This lets you execute command, and loop over its output. Each line will be stuffed into %variable, and can be expanded out in otherCommand as many times as you like, wherever you like. %variable in actual use can only have a single-letter name, e.g. %V.

"tokens=4 delims= "

This lets you split up each line by whitespace, and take the 4th chunk in that line, and stuffs it into %variable (in our case, %%P). delims looks empty, but that extra space is actually significant.

netstat -a -n -o

Just run it and find out. According to the command line help, it "Displays all connections and listening ports.", "Displays addresses and port numbers in numerical form.", and "Displays the owning process ID associated with each connection.". I just used these options since someone else suggested it, and it happened to work :)


This takes the output of the first command or program (netstat) and passes it onto a second command program (findstr). If you were using this directly on the command line, instead of inside a command string, you would use | instead of ^|.

findstr :8080

This filters any output that is passed into it, returning only lines that contain :8080.

TaskKill.exe /PID <value>

This kills a running task, using the process ID.

%%P instead of %P

This is required in batch files. If you did this on the command prompt, you would use %P instead.

Simple way to check if a string contains another string in C?

if (strstr(request, "favicon") != NULL) {
    // contains

AngularJS - Passing data between pages

You need to create a service to be able to share data between controllers.

app.factory('myService', function() {
 var savedData = {}
 function set(data) {
   savedData = data;
 function get() {
  return savedData;

 return {
  set: set,
  get: get


In your controller A:


In your controller B:

$scope.desiredLocation = myService.get();

Remember to inject myService in the controllers by passing it as a parameter.

How to add a search box with icon to the navbar in Bootstrap 3?

I'm running BS3 on a dev site and the following produces the effect/layout you're requesting. Of course you'll need the glyphicons set up in BS3.

<div class="navbar navbar-inverse navbar-static-top" role="navigation">

    <div class="navbar-header">
        <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-ex1-collapse">
        <span class="sr-only">Toggle navigation</span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <a class="navbar-brand" rel="home" href="/" title="Aahan Krish's Blog - Homepage">ITSMEEE</a>

    <div class="collapse navbar-collapse navbar-ex1-collapse">

        <ul class="nav navbar-nav">
            <li><a href="/topic/notes/">/notes</a></li>
            <li><a href="/topic/dev/">/dev</a></li>
            <li><a href="/topic/good-reads/">/good-reads</a></li>
            <li><a href="/topic/art/">/art</a></li>
            <li><a href="/topic/bookmarks/">/bookmarks</a></li>
            <li><a href="/all-topics/">/all</a></li>

        <div class="col-sm-3 col-md-3 pull-right">
        <form class="navbar-form" role="search">
        <div class="input-group">
            <input type="text" class="form-control" placeholder="Search" name="srch-term" id="srch-term">
            <div class="input-group-btn">
                <button class="btn btn-default" type="submit"><i class="glyphicon glyphicon-search"></i></button>


UPDATE: See JSFiddle

What is the difference between public, protected, package-private and private in Java?

David's answer provides the meaning of each access modifier. As for when to use each, I'd suggest making public all classes and the methods of each class that are meant for external use (its API), and everything else private.

Over time you'll develop a sense for when to make some classes package-private and when to declare certain methods protected for use in subclasses.

How to Git stash pop specific stash in 1.8.3?

As Robert pointed out, quotation marks might do the trick for you:

git stash pop stash@"{1}"

How to remove any URL within a string in Python

the shortest way

re.sub(r'http\S+', '', stringliteral)

How to parse a JSON file in swift?

The entire viewcontroller which show data in collecction view using two methods of json parsig

@IBOutlet weak var imagecollectionview: UICollectionView!
lazy var data = NSMutableData()
var dictdata : NSMutableDictionary = NSMutableDictionary()
override func viewDidLoad() {
    // Do any additional setup after loading the view, typically from a nib.

func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return dictdata.count
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

    let cell  = collectionView.dequeueReusableCellWithReuseIdentifier("CustomcellCollectionViewCell", forIndexPath: indexPath) as! CustomcellCollectionViewCell = dictdata.valueForKey("Data")?.valueForKey("location") as? String
    let url = NSURL(string: (dictdata.valueForKey("Data")?.valueForKey("avatar_url") as? String)! )

    LazyImage.showForImageView(cell.image, url:"URL
    return cell
func collectionView(collectionView: UICollectionView,
                    layout collectionViewLayout: UICollectionViewLayout,
                           sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
    let kWhateverHeightYouWant = 100
    return CGSizeMake(self.view.bounds.size.width/2, CGFloat(kWhateverHeightYouWant))

func startNewConnection()

   let url: URL = URL(string: "YOUR URL" as String)!
    let session = URLSession.shared

    let request = NSMutableURLRequest(url: url as URL)
    request.httpMethod = "GET" //set the get or post according to your request

    //        request.cachePolicy = NSURLRequest.CachePolicy.ReloadIgnoringCacheData
    request.cachePolicy = NSURLRequest.CachePolicy.reloadIgnoringCacheData

    let task = session.dataTask(with: request as URLRequest) {
        ( data, response, error) in

        guard let _:NSData = data as NSData?, let _:URLResponse = response, error == nil else {

       let jsonString = NSString(data: data!, encoding:String.Encoding.utf8.rawValue) as! String


func startConnection(){
    let urlPath: String = "your URL"
    let url: NSURL = NSURL(string: urlPath)!
    var request: NSURLRequest = NSURLRequest(URL: url)
    var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: false)!

func connection(connection: NSURLConnection!, didReceiveData data: NSData!){

func buttonAction(sender: UIButton!){

func connectionDidFinishLoading(connection: NSURLConnection!) {
    do {
        let JSON = try NSJSONSerialization.JSONObjectWithData(, options:NSJSONReadingOptions(rawValue: 0))
        guard let JSONDictionary :NSDictionary = JSON as? NSDictionary else {
            print("Not a Dictionary")
            // put in function
        print("JSONDictionary! \(JSONDictionary)")
        dictdata.setObject(JSONDictionary, forKey: "Data")

    catch let JSONError as NSError {
    }    }

Hibernate Criteria Restrictions AND / OR combination

think works

Criteria criteria = getSession().createCriteria(clazz); 
Criterion rest1= Restrictions.and(Restrictions.eq(A, "X"), 
 "B", Arrays.asList("X",Y)));
Criterion rest2= Restrictions.and(Restrictions.eq(A, "Y"), 
           Restrictions.eq(B, "Z"));
criteria.add(Restrictions.or(rest1, rest2));

Find directory name with wildcard or similar to "like"

find supports wildcard matches, just add a *:

find / -type d -name "ora10*"

What does PermGen actually stand for?

If I remember correctly, the gen stands for generation, as in a generational garbage collector (that treats younger objects differently than mid-life and "permanent" objects). Principle of locality suggests that recently created objects will be wiped out first.

Auto-expanding layout with Qt-Designer

Set the horizontalPolicy & VerticalPolicy for the controls/widgets to "Preferred".

Equivalent of varchar(max) in MySQL?

The max length of a varchar is


divided by the max byte length of a character in the character set the column is set to (e.g. utf8=3 bytes, ucs2=2, latin1=1).

minus 2 bytes to store the length

minus the length of all the other columns

minus 1 byte for every 8 columns that are nullable. If your column is null/not null this gets stored as one bit in a byte/bytes called the null mask, 1 bit per column that is nullable.

How to change RGB color to HSV?

There's a C implementation here:

Should be very straightforward to convert to C#, as almost no functions are called - just calculations.

found via Google

How to get the row number from a datatable?


int i = Convert.ToInt32(dt.Rows.Count);

I think it's the shortest, thus the simplest way.

Remove unwanted parts from strings in a column

In the particular case where you know the number of positions that you want to remove from the dataframe column, you can use string indexing inside a lambda function to get rid of that parts:

Last character:

data['result'] = data['result'].map(lambda x: str(x)[:-1])

First two characters:

data['result'] = data['result'].map(lambda x: str(x)[2:])

Does Python have “private” variables in classes?

Sorry guys for "resurrecting" the thread, but, I hope this will help someone:

In Python3 if you just want to "encapsulate" the class attributes, like in Java, you can just do the same thing like this:

class Simple:
    def __init__(self, str):
        print("inside the simple constructor")
        self.__s = str

    def show(self):

    def showMsg(self, msg):
        print(msg + ':',

To instantiate this do:

ss = Simple("lol")

Note that: print(ss.__s) will throw an error.

In practice, Python3 will obfuscate the global attribute name. Turning this like a "private" attribute, like in Java. The attribute's name is still global, but in an inaccessible way, like a private attribute in other languages.

But don't be afraid of it. It doesn't matter. It does the job too. ;)

Dynamically replace img src attribute with jQuery

In my case, I replaced the src taq using:

   $('#gmap_canvas').attr('src', newSrc);

Space between border and content? / Border distance from content?

You could try adding an<hr>and styling that. Its a minimal markup change but seems to need less css so that might do the trick.


How to create a oracle sql script spool file

In order to execute a spool file in plsql Go to File->New->command window -> paste your code-> execute. Got to the directory and u will find the file.

How do I use Bash on Windows from the Visual Studio Code integrated terminal?

You no longer need to type in bash.exe path manually. This answer is deprecated. Now you can switch to bash directly, if you have git installed in the default path. If you installed git to a different path you need to use the below solution.

Install Git from

Then open Visual Studio Code and open the command palette using Ctrl + Shift + P. Then type "open user setting", and then select "Open User Settings" from the drop down menu.

Visual Studio Code command palate

Then this tab will open up with default settings on left and your settings on the right:

enter image description here

Now copy this line of code to your own settings page (the pane on the right hand side) and save - "": "C:\\Program Files\\Git\\bin\\bash.exe"

Note: "C:\\Program Files\Git\bin\bash.exe" is the path where the bash.exe file is located from the Git installation. If you are using the Windows Subsystem for Linux (WSL) Bash shell, the path would be "C:\Windows\System32\bash.exe"

Now press Ctrl + ` to open up the terminal from Visual Studio Code. And you will have Bash -

Enter image description here

Angular - "has no exported member 'Observable'"

I had a similar issue. Back-revving RXJS from 6.x to the latest 5.x release fixed it for Angular 5.2.x.

Open package.json.

Change "rxjs": "^6.0.0", to "rxjs": "^5.5.10",

run npm update

How to retrieve images from MySQL database and display in an html tag

I have added slashes before inserting into database so on the time of fetching i removed slashes again stripslashes() and it works for me. I am sharing the code which works for me.

How i inserted into mysql db (blob type)

$db = mysqli_connect("localhost","root","","dName"); 
$image = addslashes(file_get_contents($_FILES['images']['tmp_name']));
$query = "INSERT INTO student_img (id,image) VALUES('','$image')";  
$query = mysqli_query($db, $query);

Now to access the image

$sqlQuery = "SELECT * FROM student_img WHERE id = $stid";
$rs = $db->query($sqlQuery);
echo '<img src="data:image/jpeg;base64,'.base64_encode( stripslashes($result['image']) ).'"/>';

Hope it will help someone


Fastest way to find second (third...) highest/lowest value in vector or column

topn = function(vector, n){
  for (i in 1:n){
    biggest=match(max(vector), vector)
  mat=cbind(maxs, ind)

this function will return a matrix with the top n values and their indices. hope it helps VDevi-Chou

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

What's the difference between an Angular component and module

Well, it's too late to post an answer, but I feel my explanation will be easy to understand for beginners with Angular. The following is one of the examples that I give during my presentation.

Consider your angular Application as a building. A building can have N number of apartments in it. An apartment is considered as a module. An Apartment can then have N number of rooms which correspond to the building blocks of an Angular application named components.

Now each apartment (Module)` will have rooms (Components), lifts (Services) to enable larger movement in and out the apartments, wires (Pipes) to transform around and make it useful in the apartments.

You will also have places like swimming pool, tennis court which are being shared by all building residents. So these can be considered as components inside SharedModule.

Basically, the difference is as follows,

Table showing key differences between Module and Component

Follow my slides to understand the building blocks of an Angular application

Here is my session on Building Blocks of Angular for beginners

Thymeleaf using path variables to th:href

You can use like

  1. My table is bellow like..

        <tr th:each="user: ${staffList}">
            <td><a th:href="@{'/details-view/'+ ${user.userId}}">Details</a></td>
  2. Here is my controller ..

    @GetMapping(value = "/details-view/{userId}")
    public String details(@PathVariable String userId) { 
        Logger.getLogger(getClass().getName()).info("userId-->" + userId);
     return "user-details";

How to disable the ability to select in a DataGridView?

Enabled property to false


this.dataGridView1.DefaultCellStyle.SelectionBackColor = this.dataGridView1.DefaultCellStyle.BackColor;
this.dataGridView1.DefaultCellStyle.SelectionForeColor = this.dataGridView1.DefaultCellStyle.ForeColor;

How do I check whether a file exists without exceptions?

if os.path.isfile(path_to_file):
    except IOError as e:
        print "Unable to open file"

Raising exceptions is considered to be an acceptable, and Pythonic, approach for flow control in your program. Consider handling missing files with IOErrors. In this situation, an IOError exception will be raised if the file exists but the user does not have read permissions.


How to return data from promise

I also don't like using a function to handle a property which has been resolved again and again in every controller and service. Seem I'm not alone :D

Don't tried to get result with a promise as a variable, of course no way. But I found and use a solution below to access to the result as a property.

Firstly, write result to a property of your service:

    var theParentIdResult = null;
    var factoryReturn = {  
        theParentId: theParentIdResult,
        addSiteParentId : addSiteParentId
    return factoryReturn;
    function addSiteParentId(nodeId) {   
         var theParentId = 'a';
         var parentId = relationsManagerResource.GetParentId(nodeId)
                 factoryReturn.theParentIdResult =;
                 console.log(theParentId);  // #1

Now, we just need to ensure that method addSiteParentId always be resolved before we accessed to property theParentId. We can achieve this by using some ways.

  • Use resolve in router method:

    resolve: {
        parentId: function (your_factory) {

then in controller and other services used in your router, just call your_factory.theParentId to get your property. Referce here for more information:

  • Use run method of app to resolve your service. (your_factory) { your_factory.addSiteParentId(); })
  • Inject it in the first controller or services of the controller. In the controller we can call all required init services. Then all remain controllers as children of main controller can be accessed to this property normally as you want.

Chose your ways depend on your context depend on scope of your variable and reading frequency of your variable.

Node JS Error: ENOENT

use "temp" in lieu of "tmp"


it worked for me after i realized the tmp is a temporary folder that didn't exist on my computer, but my temp was my temporary folder



I also created a new folder "tmp" in my C: drive and everything worked perfectly. The book may have missed mentioning that small step

check out to chat with some of the node.js community

How do I find which transaction is causing a "Waiting for table metadata lock" state?

I had a similar issue with Datagrip and none of these solutions worked.

Once I restarted the Datagrip Client it was no longer an issue and I could drop tables again.

When to catch java.lang.Error?

Almost never. Errors are designed to be issues that applications generally can't do anything about. The only exception might be to handle the presentation of the error but even that might not go as planned depending on the error.

How to define the css :hover state in a jQuery selector?

I would suggest to use CSS over jquery ( if possible) otherwise you can use something like this

$("div.myclass").hover(function() {

You can change your selector as per your need.

As commented by @A.Wolff, If you want to use this hover effect to multiple classes, you can use it like this

$(".myclass, .myclass2").hover(function(e) { 
    $(this).css("background-color",e.type === "mouseenter"?"red":"transparent") 

Js Fiddle Demo

Is there a Google Sheets formula to put the name of the sheet into a cell?

You have 2 options, and I am not sure if I am a fan of either of them, but that is my opinion. You may feel differently:

Option 1: Force the function to run.

A function in a cell does not run unless it references a cell that has changed. Changing a sheet name does not trigger any functions in the spreadsheet. But we can force the function to run by passing a range to it and whenever an item in that range changes, the function will trigger.

You can use the below script to create a custom function which will retrieve the name:

function mySheetName() {
  var key = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet().getName();
  return key;

and in the cell place the following:


Now if any value in a cell in that passed range changes the script will run. This takes a second to run the script and sets a message in the cell each time any value is changed so this could become annoying very quickly. As already mentioned, it also requires a change in the range to cause it to trigger, so not really helpful on a fairly static file.

Option 2: Use the OnChange Event

While the run time feels better than the above option, and this does not depend on a value changing in the spreadsheet's cells, I do not like this because it forces where the name goes. You could use a Utilities sheet to define this location in various sheets if you wish. Below is the basic idea and may get you started if you like this option.

The OnChange event is triggered when the sheet name is changed. You can make the code below more sophisticated to check for errors, check the sheet ID to only work on a given sheet, etc. The basic code, however, is:

function setSheetName(e) {
  var key = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet().getName();

Once you have saved the code, in the script editor set the Current Project's On Change Trigger to this function. It will write the sheet name to cell K1 on any change event. To set the trigger, select Current project's triggers under the Edit menu.

Javascript/Jquery to change class onclick?

      <div class="liveChatContainer online">
        <div class="actions" id="change">
         <span class="item title">Need help?</span>
              <a href="/test" onclick="demo()"><i class="fa fa-smile-o"></i>Chat</a>
              <a href="/test"><i class="fa fa-smile-o"></i>Call</a>
              <a href="/test"><i class="fa fa-smile-o"></i>Email</a>
              <a href="#" class="liveChatLabel">Contact</a>
               background-color: red;

          function demo(){

vi/vim editor, copy a block (not usual action)

It sounds like you want to place marks in the file.

mx places a mark named x under the cursor

y'x yanks everything between the cursor's current position and the line containing mark x.

You can use 'x to simply move the cursor to the line with your mark.

You can use `x (a back-tick) to move to the exact location of the mark.

One thing I do all the time is yank everything between the cursor and mark x into the clipboard.

You can do that like this:


NOTE: In some environments the clipboard buffer is represented by a * in stead of a +.

Similar questions with some good answers:

Sending Multipart File as POST parameters with RestTemplate requests

MultiValueMap<String, Object> parts = new LinkedMultiValueMap<String, Object>();
parts.add("name 1", "value 1");
parts.add("name 2", "value 2+1");
parts.add("name 2", "value 2+2");
Resource logo = new ClassPathResource("/org/springframework/http/converter/logo.jpg");
parts.add("logo", logo);
Source xml = new StreamSource(new StringReader("<root><child/></root>"));
parts.add("xml", xml);

template.postForLocation("", parts);

Tainted canvases may not be exported

Seems like you are using an image from a URL that has not set correct Access-Control-Allow-Origin header and hence the issue.. You can fetch that image from your server and get it from your server to avoid CORS issues..

What is the difference between Bower and npm?

My team moved away from Bower and migrated to npm because:

  • Programmatic usage was painful
  • Bower's interface kept changing
  • Some features, like the url shorthand, are entirely broken
  • Using both Bower and npm in the same project is painful
  • Keeping bower.json version field in sync with git tags is painful
  • Source control != package management
  • CommonJS support is not straightforward

For more details, see "Why my team uses npm instead of bower".

Read a zipped file as a pandas DataFrame

I think you want to open the ZipFile, which returns a file-like object, rather than read:

In [11]: crime2013 = pd.read_csv('crime_incidents_2013_CSV.csv'))

In [12]: crime2013
<class 'pandas.core.frame.DataFrame'>
Int64Index: 24567 entries, 0 to 24566
Data columns (total 15 columns):
CCN                            24567  non-null values
REPORTDATETIME                 24567  non-null values
SHIFT                          24567  non-null values
OFFENSE                        24567  non-null values
METHOD                         24567  non-null values
LASTMODIFIEDDATE               24567  non-null values
BLOCKSITEADDRESS               24567  non-null values
BLOCKXCOORD                    24567  non-null values
BLOCKYCOORD                    24567  non-null values
WARD                           24563  non-null values
ANC                            24567  non-null values
DISTRICT                       24567  non-null values
PSA                            24567  non-null values
NEIGHBORHOODCLUSTER            24263  non-null values
dtypes: float64(4), int64(1), object(10)

Colorized grep -- viewing the entire file with highlighted matches

To highlight patterns while viewing the whole file, h can do this.

Plus it uses different colors for different patterns.

cat FILE | h 'PAT1' 'PAT2' ...

You can also pipe the output of h to less -R for better reading.

To grep and use 1 color for each pattern, cxpgrep could be a good fit.

Iterate over object in Angular

//Get solution for ng-repeat    
//Add variable and assign with Object.key

    export class TestComponent implements OnInit{
      objectKeys = Object.keys;
      obj: object = {
        "test": "value"
        "test1": "value1"
      <div *ngFor="let key of objectKeys(obj)">
          <div class="content">{{key}}</div>
          <div class="content">{{obj[key]}}</div>

moment.js 24h format

You can use

 moment("15", "hh").format('LT') 

to convert the time to 12 hours format like this 3:00 PM

Changing Tint / Background color of UITabBar

for just background color

Tabbarcontroller.tabBar.barTintColor=[UIColor redcolour];

or this in App Delegate

[[UITabBar appearance] setBackgroundColor:[UIColor blackColor]];

for changing color of unselect icons of tabbar

For iOS 10:

// this code need to be placed on home page of tabbar    
for(UITabBarItem *item in self.tabBarController.tabBar.items) {
    item.image = [item.image imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

Above iOS 10:

// this need to be in appdelegate didFinishLaunchingWithOptions
[[UITabBar appearance] setUnselectedItemTintColor:[UIColor blackColor]];

How to check if a variable exists in a FreeMarker template?

For versions previous to FreeMarker 2.3.7

You can not use ?? to handle missing values, the old syntax is:

<#if userName?exists>
   Hi ${userName}, How are you?

Exporting to .xlsx using Microsoft.Office.Interop.Excel SaveAs Error

myBook.Saved = true;
myBook.Close(null, null, null);

SignalR Console app example

This is for dot net core 2.1 - after a lot of trial and error I finally got this to work flawlessly:

var url = "Hub URL goes here";

var connection = new HubConnectionBuilder()
    .WithAutomaticReconnect() //I don't think this is totally required, but can't hurt either

//Start the connection
var t = connection.StartAsync();

//Wait for the connection to complete

//Make your call - but in this case don't wait for a response 
//if your goal is to set it and forget it
await connection.InvokeAsync("SendMessage", "User-Server", "Message from the server");

This code is from your typical SignalR poor man's chat client. The problem that I and what seems like a lot of other people have run into is establishing a connection before attempting to send a message to the hub. This is critical, so it is important to wait for the asynchronous task to complete - which means we are making it synchronous by waiting for the task to complete.

“Origin null is not allowed by Access-Control-Allow-Origin” error for request made by application running from a file:// URL

You need to maybe add a HEADER in your called script, here is what I had to do in PHP:

header('Access-Control-Allow-Origin: *');

More details in Cross domain AJAX ou services WEB (in French).

SQL: How to get the id of values I just INSERTed?

Again no language agnostic response, but in Java it goes like this:

Connection conn = Database.getCurrent().getConnection();  
PreparedStatement ps =  conn.prepareStatement(insertSql, Statement.RETURN_GENERATED_KEYS);
try {  
    ResultSet rs = ps.getGeneratedKeys();;  
    long primaryKey = rs.getLong(1);  
} finally {  

How to convert string to integer in PowerShell

You can specify the type of a variable before it to force its type. It's called (dynamic) casting (more information is here):

$string = "1654"
$integer = [int]$string

$string + 1
# Outputs 16541

$integer + 1
# Outputs 1655

As an example, the following snippet adds, to each object in $fileList, an IntVal property with the integer value of the Name property, then sorts $fileList on this new property (the default is ascending), takes the last (highest IntVal) object's IntVal value, increments it and finally creates a folder named after it:

# For testing purposes
#$fileList = @([PSCustomObject]@{ Name = "11" }, [PSCustomObject]@{ Name = "2" }, [PSCustomObject]@{ Name = "1" })
# OR
#$fileList = New-Object -TypeName System.Collections.ArrayList
#$fileList.AddRange(@([PSCustomObject]@{ Name = "11" }, [PSCustomObject]@{ Name = "2" }, [PSCustomObject]@{ Name = "1" })) | Out-Null

$highest = $fileList |
    Select-Object *, @{ n = "IntVal"; e = { [int]($_.Name) } } |
    Sort-Object IntVal |
    Select-Object -Last 1

$newName = $highest.IntVal + 1

New-Item $newName -ItemType Directory

Sort-Object IntVal is not needed so you can remove it if you prefer.

[int]::MaxValue = 2147483647 so you need to use the [long] type beyond this value ([long]::MaxValue = 9223372036854775807).

HTTP GET with request body

I am using the Spring framework's RestTemplate in my client programme and, at the server-side, I defined a GET request with a Json body. My primary purpose is the same as yours: when the request has numerous parameters, putting them in the body seems tidier than putting them in the prolonged URI string. Yes?

But, sadly, it's not working! The server-side threw the following exception:

org.springframework.http.converter.HttpMessageNotReadableException: Required request body is missing...

But I am pretty sure the message body is correctly provided by my client code, so what's wrong?

I traced into the method and found the following:

// SimpleClientHttpRequestFactory.class
public class SimpleClientHttpRequestFactory implements ClientHttpRequestFactory, AsyncClientHttpRequestFactory {
    protected void prepareConnection(HttpURLConnection connection, String httpMethod) throws IOException {
        if (!"POST".equals(httpMethod) && !"PUT".equals(httpMethod) && !"PATCH".equals(httpMethod) && !"DELETE".equals(httpMethod)) {
        } else {

// SimpleBufferingClientHttpRequest.class
final class SimpleBufferingClientHttpRequest extends AbstractBufferingClientHttpRequest {
    protected ClientHttpResponse executeInternal(HttpHeaders headers, byte[] bufferedOutput) throws IOException {
        if (this.connection.getDoOutput() && this.outputStreaming) {

        if (this.connection.getDoOutput()) {
            FileCopyUtils.copy(bufferedOutput, this.connection.getOutputStream());
        } else {

Please notice that in the executeInternal() method, the input argument 'bufferedOutput' contains the message body provided by my code. I saw it through the debugger.

However, due to the prepareConnection(), the getDoOutput() in executeInternal() always returns false which, in turn, makes the bufferedOutput completely ignored! It's not copied into the output stream.

Consequently, my server programme received no message body and threw that exception.

This is an example about the RestTemplate of the Spring framework. The point is that, even if the message body is no longer forbidden by the HTTP spec, some client or server libraries or frameworks might still comply with the old spec and reject the message body from the GET request.

How can I convert IPV6 address to IPV4 address?

While there are IPv6 equivalents for the IPv4 address range, you can't convert all IPv6 addresses to IPv4 - there are more IPv6 addresses than there are IPv4 addresses.

The only sane way around this issue is to update your application to be able to understand and store IPv6 addresses.

Insert the same fixed value into multiple rows

You're looking for UPDATE not insert.

UPDATE mytable
SET    table_column = 'test';

UPDATE will change the values of existing rows (and can include a WHERE to make it only affect specific rows), whereas INSERT is adding a new row (which makes it look like it changed only the last row, but in effect is adding a new row with that value).

Less aggressive compilation with CSS3 calc

A very common usecase of calc is take 100% width and adding some margin around the element.

One can do so with:

@someMarginVariable = 15px;

margin: @someMarginVariable;
width: calc(~"100% - "@someMarginVariable*2);
width: -moz-calc(~"100% - "@someMarginVariable*2);
width: -webkit-calc(~"100% - "@someMarginVariable*2);

How to replace a string in an existing file in Perl?


Uh, what??



or, if you insist on using a variable (which is not necessary when using $_, but I just want to show the right syntax):

$_ =~ s/blue/red/g;

Fetching data from MySQL database to html dropdown list

# here database details      
mysql_connect('hostname', 'username', 'password');

$sql = "SELECT username FROM userregistraton";
$result = mysql_query($sql);

echo "<select name='username'>";
while ($row = mysql_fetch_array($result)) {
    echo "<option value='" . $row['username'] ."'>" . $row['username'] ."</option>";
echo "</select>";

# here username is the column of my table(userregistration)
# it works perfectly

Bootstrap 3.0 Popovers and tooltips

I use this on all my pages to enable tooltip

$(function () { $("[data-toggle='tooltip']").tooltip(); });

Android ViewPager with bottom dots

Following is my proposed solution.

  • Since we need to show only some images in the view pagers so have avoided the cumbersome use of fragments.
    • Implemented the view page indicators (the bottom dots without any extra library or plugin)
    • On the touch of the view page indicators(the dots) also the page navigation is happening.
    • Please don"t forget to add your own images in the resources.
    • Feel free to comment and improve upon it.

A) Following is my activity_main.xml

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

    < xmlns:android=""
        android:layout_height="wrap_content" />


            android:orientation="horizontal" />



B) pager_item.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android=""
    android:orientation="vertical" android:layout_width="match_parent"

        android:id="@+id/imageView" />


import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity implements ViewPager.OnPageChangeListener, View.OnClickListener {

    int[] mResources = {R.drawable.nature1, R.drawable.nature2, R.drawable.nature3, R.drawable.nature4,
            R.drawable.nature5, R.drawable.nature6

    ViewPager mViewPager;
    private CustomPagerAdapter mAdapter;
    private LinearLayout pager_indicator;
    private int dotsCount;
    private ImageView[] dots;

    protected void onCreate(Bundle savedInstanceState) {

        mViewPager = (ViewPager) findViewById(;
        pager_indicator = (LinearLayout) findViewById(;
        mAdapter = new CustomPagerAdapter(this, mResources);



    private void setPageViewIndicator() {

        Log.d("###setPageViewIndicator", " : called");
        dotsCount = mAdapter.getCount();
        dots = new ImageView[dotsCount];

        for (int i = 0; i < dotsCount; i++) {
            dots[i] = new ImageView(this);

            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(

            params.setMargins(4, 0, 4, 0);

            final int presentPosition = i;
            dots[presentPosition].setOnTouchListener(new View.OnTouchListener() {

                public boolean onTouch(View v, MotionEvent event) {
                    return true;


            pager_indicator.addView(dots[i], params);


    public void onClick(View v) {


    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {


    public void onPageSelected(int position) {

        Log.d("###onPageSelected, pos ", String.valueOf(position));
        for (int i = 0; i < dotsCount; i++) {


        if (position + 1 == dotsCount) {

        } else {


    public void onPageScrollStateChanged(int state) {



 import android.content.Context;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ImageView;
    import android.widget.LinearLayout;

    public class CustomPagerAdapter extends PagerAdapter {
        private Context mContext;
        LayoutInflater mLayoutInflater;
        private int[] mResources;

        public CustomPagerAdapter(Context context, int[] resources) {
            mContext = context;
            mLayoutInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            mResources = resources;

        public Object instantiateItem(ViewGroup container, int position) {

            View itemView = mLayoutInflater.inflate(R.layout.pager_item,container,false);
            ImageView imageView = (ImageView) itemView.findViewById(;
           /* LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(950, 950);
            return itemView;

        public void destroyItem(ViewGroup collection, int position, Object view) {
            collection.removeView((View) view);

        public int getCount() {
            return mResources.length;

        public boolean isViewFromObject(View view, Object object) {
            return view == object;

E) selecteditem_dot.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android=""
    android:shape="oval" android:useLevel="true"

    <size android:height="12dip" android:width="12dip"/>

    <solid android:color="#7e7e7e"/>

F) nonselecteditem_dot.xml

 <?xml version="1.0" encoding="utf-8"?>
    <shape xmlns:android=""
        android:shape="oval" android:useLevel="true"
        <size android:height="12dip" android:width="12dip"/>        
        <solid android:color="#d3d3d3"/>

first image

enter image description here

jQuery, get html of a whole element

You can achieve that with just one line code that simplify that:


As simple as that.

SyntaxError: Use of const in strict mode?

This is probably not the solution for everyone, but it was for me.

If you are using NVM, you might not have enabled the right version of node for the code you are running. After you reboot, your default version of node changes back to the system default.

Was running into this when working with react-native which had been working fine. Just use nvm to use the right version of node to solve this problem.

Can you blur the content beneath/behind a div?

If you want to enable unblur, you cannot just add the blur CSS to the body, you need to blur each visible child one level directly under the body and then remove the CSS to unblur. The reason is because of the "Cascade" in CSS, you cannot undo the cascading of the CSS blur effect for a child of the body. Also, to blur the body's background image you need to use the pseudo element :before


<div id="fullscreen-popup" style="position:absolute;top:50%;left:50%;">
    <div class="morph-button morph-button-overlay morph-button-fixed">
        <button id="user-interface" type="button">MORE INFO</button>
        <!--a id="user-interface" href="javascript:void(0)">popup</a-->
        <div class="morph-content">
                <div class="content-style-overlay">
                    <span class="icon icon-close">Close the overlay</span>
                    <h2>About Parsley</h2>
                    <p>Gumbo beet greens corn soko endive gumbo gourd. Parsley shallot courgette tatsoi pea sprouts fava bean collard greens dandelion okra wakame tomato. Dandelion cucumber earthnut pea peanut soko zucchini.</p>
                    <p>Turnip greens yarrow ricebean rutabaga endive cauliflower sea lettuce kohlrabi amaranth water spinach avocado daikon napa cabbage asparagus winter purslane kale. Celery potato scallion desert raisin horseradish spinach carrot soko. Lotus root water spinach fennel kombu maize bamboo shoot green bean swiss chard seakale pumpkin onion chickpea gram corn pea. Brussels sprout coriander water chestnut gourd swiss chard wakame kohlrabi beetroot carrot watercress. Corn amaranth salsify bunya nuts nori azuki bean chickweed potato bell pepper artichoke.</p>
                    <p>Gumbo beet greens corn soko endive gumbo gourd. Parsley shallot courgette tatsoi pea sprouts fava bean collard greens dandelion okra wakame tomato. Dandelion cucumber earthnut pea peanut soko zucchini.</p>
                    <p>Turnip greens yarrow ricebean rutabaga endive cauliflower sea lettuce kohlrabi amaranth water spinach avocado daikon napa cabbage asparagus winter purslane kale. Celery potato scallion desert raisin horseradish spinach carrot soko. Lotus root water spinach fennel kombu maize bamboo shoot green bean swiss chard seakale pumpkin onion chickpea gram corn pea. Brussels sprout coriander water chestnut gourd swiss chard wakame kohlrabi beetroot carrot watercress. Corn amaranth salsify bunya nuts nori azuki bean chickweed potato bell pepper artichoke.</p>
                    <p>Gumbo beet greens corn soko endive gumbo gourd. Parsley shallot courgette tatsoi pea sprouts fava bean collard greens dandelion okra wakame tomato. Dandelion cucumber earthnut pea peanut soko zucchini.</p>
                    <p>Turnip greens yarrow ricebean rutabaga endive cauliflower sea lettuce kohlrabi amaranth water spinach avocado daikon napa cabbage asparagus winter purslane kale. Celery potato scallion desert raisin horseradish spinach carrot soko. Lotus root water spinach fennel kombu maize bamboo shoot green bean swiss chard seakale pumpkin onion chickpea gram corn pea. Brussels sprout coriander water chestnut gourd swiss chard wakame kohlrabi beetroot carrot watercress. Corn amaranth salsify bunya nuts nori azuki bean chickweed potato bell pepper artichoke.</p>


/* Blur - doesn't work on IE */

.blur-on, .blur-element {
    -webkit-filter: blur(10px);
    -moz-filter: blur(10px);
    -o-filter: blur(10px);
    -ms-filter: blur(10px);
    filter: blur(10px);

    -webkit-transition: all 5s linear;
    transition        : all 5s linear;
    -moz-transition   : all 5s linear;
    -webkit-transition: all 5s linear;
    -o-transition     : all 5s linear;
.blur-off {
    -webkit-filter: blur(0px) !important;
    -moz-filter   : blur(0px) !important;
    -o-filter     : blur(0px) !important;
    -ms-filter    : blur(0px) !important;
    filter        : blur(0px) !important;
.blur-bgimage:before {
    content: "";
    position: absolute;
    height: 20%; width: 20%;
    background-size: cover;
    background: inherit;
    z-index: -1;

    transform: scale(5);
    transform-origin: top left;
    filter: blur(2px);       
    -moz-transform: scale(5);
    -moz-transform-origin: top left;
    -moz-filter: blur(2px);       
    -webkit-transform: scale(5);
    -webkit-transform-origin: top left;
    -webkit-filter: blur(2px);
    -o-transform: scale(5);
    -o-transform-origin: top left;
    -o-filter: blur(2px);       

    transition        : all 5s linear;
    -moz-transition   : all 5s linear;
    -webkit-transition: all 5s linear;
    -o-transition     : all 5s linear;


function blurBehindPopup() {
    if(blurredElements.length == 0) {
        for(var i=0; i < document.body.children.length; i++) {
            var element = document.body.children[i];
            if( && != 'fullscreen-popup' && element.isVisible == true) {
                classie.addClass( element, 'blur-element' );
    } else {
        for(var i=0; i < blurredElements.length; i++) {
            classie.addClass( blurredElements[i], 'blur-element' );
function unblurBehindPopup() {
    for(var i=0; i < blurredElements.length; i++) {
        classie.removeClass( blurredElements[i], 'blur-element' );

Full Working Example Link

Laravel: PDOException: could not find driver

For me, these steps worked in Ubuntu with PHP 7.3:

1. vi /etc/php/7.3/apache2/php.ini > uncomment:
2. sudo apt-get install php7.3-sqlite3
3. sudo service apache2 restart

Animate background image change with jQuery

I had the same problem, after loads of research and Googling, I found the following solution worked best for me! plenty of trial and error went into this one.



$(document).ready(function() {
                $(this).css({"background-image":"url(<?php bloginfo('template_url') ?>/img/header-boy-hover.jpg)"});


header {
    -webkit-transition:all 1s ease-in;
    -moz-transition:all 1s ease-in;
    -o-transition:all 1s ease-in;
    -ms-transition:all 1s ease-in;
    transition:all 1s ease-in;

Objective-C for Windows

WinObjC? Windows Bridge for iOS (previously known as ‘Project Islandwood’).

Windows Bridge for iOS (also referred to as WinObjC) is a Microsoft open source project that provides an Objective-C development environment for Visual Studio/Windows. In addition, WinObjC provides support for iOS API compatibility. While the final release will happen later this fall (allowing the bridge to take advantage of new tooling capabilities that will ship with the upcoming Visual Studio 2015 Update),

The bridge is available to the open-source community now in its current state. Between now and the fall. The iOS bridge as an open-source project under the MIT license. Given the ambition of the project, making it easy for iOS developers to build and run apps on Windows.

Salmaan Ahmed has an in-depth post on the Windows Bridge for iOS discussing the compiler, runtime, IDE integration, and what the bridge is and isn’t. Best of all, the source code for the iOS bridge is live on GitHub right now.

The iOS bridge supports both Windows 8.1 and Windows 10 apps built for x86 and x64 processor architectures, and soon we will add compiler optimizations and support for ARM, which adds mobile support.

Xcode "Device Locked" When iPhone is unlocked

I ran in to the same issue even though i selected "Trust this computer" option first time.

This worked for me

  1. Lock the device
  2. Remove cable from device.
  3. Unlock the device
  4. Connect again to Mac

How to ignore PKIX path building failed:

I also came across the same issue. I was trying to build the project with a clean install goal. I simply changed it to clean package -o in the run configuration. Then I re-built the project and it worked for me.

How can I autoformat/indent C code in vim?

I wanted to add, that in order to prevent it from being messed up in the first place you can type :set paste before pasting. After pasting, you can type :set nopaste for things like js-beautify and indenting to work again.

How do I redirect users after submit button click?

Your submission will cancel the redirect or vice versa.

I do not see the reason for the redirect in the first place since why do you have an order form that does nothing.

That said, here is how to do it. Firstly NEVER put code on the submit button but do it in the onsubmit, secondly return false to stop the submission

NOTE This code will IGNORE the action and ONLY execute the script due to the return false/preventDefault

function redirect() {
  return false;


<form name="form1" id="form1" method="post" onsubmit="return redirect()">  
  <input type="submit" class="button4" name="order" id="order" value="Place Order" >

Or unobtrusively:

window.onload=function() {
  document.getElementById("form1").onsubmit=function() {
    return false;


<form id="form1" method="post">  
  <input type="submit" class="button4" value="Place Order" >


$("#form1").on("submit",function(e) {
   e.preventDefault(); // cancel submission



$("#form1").on("submit", function(e) {_x000D_
  e.preventDefault(); // cancel submission_x000D_
  alert("this could redirect to login.php"); _x000D_
<script src=""></script>_x000D_
<form id="form1" method="post" action="javascript:alert('Action!!!')">_x000D_
  <input type="submit" class="button4" value="Place Order">_x000D_

Regular Expression for password validation

Long, and could maybe be shortened. Supports special characters ?"-_.


Match groups in Python

Less efficient, but simpler-looking:

m0 = re.match("I love (\w+)", statement)
m1 = re.match("Ich liebe (\w+)", statement)
m2 = re.match("Je t'aime (\w+)", statement)
if m0:
  print "He loves",
elif m1:
  print "Er liebt",
elif m2:
  print "Il aime",

The problem with the Perl stuff is the implicit updating of some hidden variable. That's simply hard to achieve in Python because you need to have an assignment statement to actually update any variables.

The version with less repetition (and better efficiency) is this:

pats = [
    ("I love (\w+)", "He Loves {0}" ),
    ("Ich liebe (\w+)", "Er Liebe {0}" ),
    ("Je t'aime (\w+)", "Il aime {0}")
for p1, p3 in pats:
    m= re.match( p1, statement )
    if m:
        print p3.format( )

A minor variation that some Perl folk prefer:

pats = {
    "I love (\w+)" : "He Loves {0}",
    "Ich liebe (\w+)" : "Er Liebe {0}",
    "Je t'aime (\w+)" : "Il aime {0}",
for p1 in pats:
    m= re.match( p1, statement )
    if m:
        print pats[p1].format( )

This is hardly worth mentioning except it does come up sometimes from Perl programmers.

How to Set/Update State of StatefulWidget from other StatefulWidget in Flutter?

Old one but I would add my answer as per my findings:

var ancestralState = context.findAncestorStateOfType<ParentState>();
      ancestralState.setState(() {
        // here you can access public vars and update state.

How can I get terminal output in python?

You can use Popen in subprocess as they suggest.

with os, which is not recomment, it's like below:

import os
a  = os.popen('pwd').readlines()

Disable cache for some images

I checked all the answers and the best one seemed to be (which isn't):

<img src="image.png?cache=none">

at first.

However, if you add cache=none parameter (which is static "none" word), it doesn't effect anything, browser still loads from cache.

Solution to this problem was:

<img src="image.png?nocache=<?php echo time(); ?>">

where you basically add unix timestamp to make the parameter dynamic and no cache, it worked.

However, my problem was a little different: I was loading on the fly generated php chart image, and controlling the page with $_GET parameters. I wanted the image to be read from cache when the URL GET parameter stays the same, and do not cache when the GET parameters change.

To solve this problem, I needed to hash $_GET but since it is array here is the solution:

$chart_hash = md5(implode('-', $_GET));
echo "<img src='/images/mychart.png?hash=$chart_hash'>";


Although the above solution works just fine, sometimes you want to serve the cached version UNTIL the file is changed. (with the above solution, it disables the cache for that image completely) So, to serve cached image from browser UNTIL there is a change in the image file use:

echo "<img src='/images/mychart.png?hash=" . filemtime('mychart.png') . "'>";

filemtime() gets file modification time.

'cout' was not declared in this scope

Put the following code before int main():

using namespace std;

And you will be able to use cout.

For example:

using namespace std;
int main(){
    char t = 'f';
    char *t1;
    char **t2;
    return 0;

Now take a moment and read up on what cout is and what is going on here:

Further, while its quick to do and it works, this is not exactly a good advice to simply add using namespace std; at the top of your code. For detailed correct approach, please read the answers to this related SO question.

Set a cookie to never expire

Can't you just say a never ending loop, cookie expires as current date + 1 so it never hits the date it's supposed to expire on because it's always tomorrow? A bit overkill but just saying.

How to get difference between two rows for a column field?

select t1.rowInt,t1.Value,t2.Value-t1.Value as diff
from (select * from myTable) as t1,
     (select * from myTable where rowInt!=1
      union all select top 1 rowInt=COUNT(*)+1,Value=0 from myTable) as t2
where t1.rowInt=t2.rowInt-1

downloading all the files in a directory with cURL

Oh, I have just the thing you need!

$host = "";
$savePath = "downloadedFiles";
if($check = isFtpUp($host)){

    echo $ip." -is alive<br />";

    $check = trim($check);
    $files = explode("\n",$check);

    foreach($files as $n=>$file){
        $file = trim($file);
        if($file !== "." || $file !== ".."){
            if(!saveFtpFile($file, $host.$file, $savePath)){
                // downloading failed. possible reason: $file is a folder name.
                // echo "Error downloading file.<br />";
                echo "File: ".$file." - saved!<br />";
            // do nothing
    echo $ip." - is down.<br />";

and functions isFtpUp and saveFtpFile are as follows:

function isFtpUp($host){
$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, $host);
curl_setopt($ch, CURLOPT_USERPWD, "anonymous:[email protected]");
curl_setopt($ch, CURLOPT_FTPLISTONLY, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_TIMEOUT, 3);

$result = curl_exec($ch);

return $result;


function saveFtpFile( $targetFile = null, $sourceFile = null, $savePath){

// function settings
$timeout = 60;
$ftpuser = "anonymous";
$ftppassword = "[email protected]";
$savePath = "downloadedFiles"; // should exist!
$curl = curl_init();
$file = @fopen ($savePath.'/'.$targetFile, 'w');

    return false;

curl_setopt($curl, CURLOPT_URL, $sourceFile);
curl_setopt($curl, CURLOPT_USERPWD, $ftpuser.':'.$ftppassword);

// curl settings

// curl_setopt($curl, CURLOPT_FAILONERROR, 1);
// curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_TIMEOUT, $timeout);
curl_setopt($curl, CURLOPT_FILE, $file);

$result = curl_exec($curl);

    return false;


return $result;


it's a php script. save it as a .php file, put it on your webserver, change $ip to address(need not be ip) of ftp server you want to download files from, create a directory named downloadedFiles on the same directory as this file.

Safe String to BigDecimal conversion

The code could be cleaner, but this seems to do the trick for different locales.

import java.math.BigDecimal;
import java.text.DecimalFormatSymbols;
import java.util.Locale;

public class Main
    public static void main(String[] args)
        final BigDecimal numberA;
        final BigDecimal numberB;

        numberA = stringToBigDecimal("1,000,000,000.999999999999999", Locale.CANADA);
        numberB = stringToBigDecimal(",999999999999999", Locale.GERMANY);

    private static BigDecimal stringToBigDecimal(final String formattedString,
                                                 final Locale locale)
        final DecimalFormatSymbols symbols;
        final char                 groupSeparatorChar;
        final String               groupSeparator;
        final char                 decimalSeparatorChar;
        final String               decimalSeparator;
        String                     fixedString;
        final BigDecimal           number;

        symbols              = new DecimalFormatSymbols(locale);
        groupSeparatorChar   = symbols.getGroupingSeparator();
        decimalSeparatorChar = symbols.getDecimalSeparator();

        if(groupSeparatorChar == '.')
            groupSeparator = "\\" + groupSeparatorChar;
            groupSeparator = Character.toString(groupSeparatorChar);

        if(decimalSeparatorChar == '.')
            decimalSeparator = "\\" + decimalSeparatorChar;
            decimalSeparator = Character.toString(decimalSeparatorChar);

        fixedString = formattedString.replaceAll(groupSeparator , "");
        fixedString = fixedString.replaceAll(decimalSeparator , ".");
        number      = new BigDecimal(fixedString);

        return (number);

How can I use Timer (formerly NSTimer) in Swift?

timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(createEnemy), userInfo: nil, repeats: true)

And Create Fun By The Name createEnemy

fund createEnemy ()
do anything ////

How do I make a JSON object with multiple arrays?

A good book I'm reading: Professional JavaScript for Web Developers by Nicholas C. Zakas 3rd Edition has the following information regarding JSON Syntax:

"JSON Syntax allows the representation of three types of values".

Regarding the one you're interested in, Arrays it says:

"Arrays are represented in JSON using array literal notation from JavaScript. For example, this is an array in JavaScript:

var values = [25, "hi", true];

You can represent this same array in JSON using a similar syntax:

[25, "hi", true]

Note the absence of a variable or a semicolon. Arrays and objects can be used together to represent more complex collections of data, such as:

                    "title": "Professional JavaScript",
                    "authors": [
                        "Nicholas C. Zakas"
                    "edition": 3,
                    "year": 2011
                    "title": "Professional JavaScript",
                    "authors": [
                        "Nicholas C.Zakas"
                    "edition": 2,
                    "year": 2009
                    "title": "Professional Ajax",
                    "authors": [
                        "Nicholas C. Zakas",
                        "Jeremy McPeak",
                        "Joe Fawcett"
                    "edition": 2,
                    "year": 2008

This Array contains a number of objects representing books, Each object has several keys, one of which is "authors", which is another array. Objects and arrays are typically top-level parts of a JSON data structure (even though this is not required) and can be used to create a large number of data structures."

To serialize (convert) a JavaScript object into a JSON string you can use the JSON object stringify() method. For the example from Mark Linus answer:

var cars = [{
    color: 'gray',
    model: '1',
    nOfDoors: 4
    color: 'yellow',
    model: '2',
    nOfDoors: 4

cars is now a JavaScript object. To convert it into a JSON object you could do:

var jsonCars = JSON.stringify(cars);

Which yields:


To do the opposite, convert a JSON object into a JavaScript object (this is called parsing), you would use the parse() method. Search for those terms if you need more information... or get the book, it has many examples.

How to remove old Docker containers

I'm using:

docker rm -v $(docker ps -a -q -f status=exited)

to delete exited containers and:

docker rmi -f $(docker images | grep "<none>" | awk "{print \$3}")

in order to get rid of all untagged images.

NSString property: copy or retain?

For strings in general, is it always a good idea to use the copy attribute instead of retain?

Yes - in general always use the copy attribute.

This is because your NSString property can be passed an NSString instance or an NSMutableString instance, and therefore we can not really determine if the value being passed is an immutable or mutable object.

Is a "copied" property in any way less efficient than such a "retain-ed" property?

  • If your property is being passed an NSString instance, the answer is "No" - copying is not less efficient than retain.
    (It's not less efficient because the NSString is smart enough to not actually perform a copy.)

  • If your property is passed an NSMutableString instance then the answer is "Yes" - copying is less efficient than retain.
    (It's less efficient because an actual memory allocation and copy must occur, but this is probably a desirable thing.)

  • Generally speaking a "copied" property has the potential to be less efficient - however through the use of the NSCopying protocol, it's possible to implement a class which is "just as efficient" to copy as it is to retain. NSString instances are an example of this.

Generally (not just for NSString), when should I use "copy" instead of "retain"?

You should always use copy when you don't want the internal state of the property changing without warning. Even for immutable objects - properly written immutable objects will handle copy efficiently (see next section regarding immutability and NSCopying).

There may be performance reasons to retain objects, but it comes with a maintenance overhead - you must manage the possibility of the internal state changing outside your code. As they say - optimize last.

But, I wrote my class to be immutable - can't I just "retain" it?

No - use copy. If your class is really immutable then it's best practice to implement the NSCopying protocol to make your class return itself when copy is used. If you do this:

  • Other users of your class will gain the performance benefits when they use copy.
  • The copy annotation makes your own code more maintainable - the copy annotation indicates that you really don't need to worry about this object changing state elsewhere.

SQL MAX of multiple columns?

Either of the two samples below will work:

SELECT  MAX(date_columns) AS max_date
FROM    ( (SELECT   date1 AS date_columns
           FROM     data_table         )
          ( SELECT  date2 AS date_columns
            FROM    data_table
          ( SELECT  date3 AS date_columns
            FROM    data_table
        ) AS date_query

The second is an add-on to lassevk's answer.

SELECT  MAX(MostRecentDate)
FROM    ( SELECT    CASE WHEN date1 >= date2
                              AND date1 >= date3 THEN date1
                         WHEN date2 >= date1
                              AND date2 >= date3 THEN date2
                         WHEN date3 >= date1
                              AND date3 >= date2 THEN date3
                         ELSE date1
                    END AS MostRecentDate
          FROM      data_table
        ) AS date_query 

httpd-xampp.conf: How to allow access to an external IP besides localhost?

<LocationMatch "^/(?i:(?:xampp|licenses|phpmyadmin|webalizer|server-status|server-info))">
Order deny,allow
Deny from all
Allow from all
Allow from ::1 
ErrorDocument 403 /error/HTTP_XAMPP_FORBIDDEN.html.var

add to txt file > httpd-xampp.conf

Maven plugins can not be found in IntelliJ

I tried the other answers, but none of them solved this problem for me.

The problem disappeared when I explicitly added the groupId like this:


Once the color of the version number changed from red to black and the problem disappeared from the Problems tab the groupId can be removed again from the problematic plugin, the error does not show up again and the version number even shows up as suggestion for version.

Jest spyOn function called

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

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

class App extends Component {

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

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

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

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

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

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

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

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

How do I set the proxy to be used by the JVM

I am also behind firewall, this worked for me!!

System.setProperty("http.proxyHost", "proxy host addr");
System.setProperty("http.proxyPort", "808");
Authenticator.setDefault(new Authenticator() {
    protected PasswordAuthentication getPasswordAuthentication() {

        return new PasswordAuthentication("domain\\user","password".toCharArray());

URL url = new URL("");
URLConnection con = url.openConnection();

BufferedReader in = new BufferedReader(new InputStreamReader(

// Read it ...
String inputLine;
while ((inputLine = in.readLine()) != null)


Accessing a class' member variables in Python?

If you have an instance function (i.e. one that gets passed self) you can use self to get a reference to the class using self.__class__

For example in the code below tornado creates an instance to handle get requests, but we can get hold of the get_handler class and use it to hold a riak client so we do not need to create one for every request.

import tornado.web
import riak

class get_handler(tornado.web.requestHandler):
    riak_client = None

    def post(self):
        cls = self.__class__
        if cls.riak_client is None:
            cls.riak_client = riak.RiakClient(pb_port=8087, protocol='pbc')
        # Additional code to send response to the request ...

System has not been booted with systemd as init system (PID 1). Can't operate

I was trying to start Docker within ubuntu and WSL.

This worked for me,

sudo service docker start

A table name as a variable

Also, you can use this...

DECLARE @SeqID varchar(150);
DECLARE @TableName varchar(150);
SET @TableName = (Select TableName from Table);
SET @SeqID = 'SELECT NEXT VALUE FOR ' + @TableName + '_Data'
exec (@SeqID)

iPad Multitasking support requires these orientations

In Xcode, check the "Requires Full Screen" checkbox under General > Targets, as shown below.

enter image description here

SQL Server 2008 Row Insert and Update timestamps

As an alternative to using a trigger, you might like to consider creating a stored procedure to handle the INSERTs that takes most of the columns as arguments and gets the CURRENT_TIMESTAMP which it includes in the final INSERT to the database. You could do the same for the CREATE. You may also be able to set things up so that users cannot execute INSERT and CREATE statements other than via the stored procedures.

I have to admit that I haven't actually done this myself so I'm not at all sure of the details.

How do I create a branch?

Create a new branch using the svn copy command as follows:

$ svn copy svn+ssh:// \
           svn+ssh:// \
      -m "Creating a branch of project"

Drop all duplicate rows across multiple columns in Python Pandas

use groupby and filter

import pandas as pd
df = pd.DataFrame({"A":["foo", "foo", "foo", "bar"], "B":[0,1,1,1], "C":["A","A","B","A"]})
df.groupby(["A", "C"]).filter(lambda df:df.shape[0] == 1)

XAMPP MySQL password setting (Can not enter in PHPMYADMIN)

If all the other answers do not work for you check the for the following:

$cfg['Servers'][$i]['host'] = '';

…and add the port of MySQL set in your XAMPP as shown below:

$cfg['Servers'][$i]['host'] = '';

Stop MySQL from XAMPP and restart MySQL.

Open a fresh page for http://localhost:8012/phpmyadmin/ and check.

How to get UTC value for SYSDATE on Oracle

I'm using:


It's working fine for me.

Is there a performance difference between a for loop and a for-each loop?

The for-each loop should generally be preferred. The "get" approach may be slower if the List implementation you are using does not support random access. For example, if a LinkedList is used, you would incur a traversal cost, whereas the for-each approach uses an iterator that keeps track of its position in the list. More information on the nuances of the for-each loop.

I think the article is now here: new location

The link shown here was dead.

Test for existence of nested JavaScript object key

Based on this answer, I came up with this generic function using ES2015 which would solve the problem

function validChain( object, ...keys ) {
    return keys.reduce( ( a, b ) => ( a || { } )[ b ], object ) !== undefined;

var test = {
  first: {
    second: {
        third: "This is not the key your are looking for"

if ( validChain( test, "first", "second", "third" ) ) {
    console.log( test.first.second.third );

How to change webservice url endpoint?

IMO, the provider is telling you to change the service endpoint (i.e. where to reach the web service), not the client endpoint (I don't understand what this could be). To change the service endpoint, you basically have two options.

Use the Binding Provider to set the endpoint URL

The first option is to change the BindingProvider.ENDPOINT_ADDRESS_PROPERTY property value of the BindingProvider (every proxy implements interface):

EchoService service = new EchoService();
Echo port = service.getEchoPort();

/* Set NEW Endpoint Location */
String endpointURL = "http://NEW_ENDPOINT_URL";
BindingProvider bp = (BindingProvider)port;
bp.getRequestContext().put(BindingProvider.ENDPOINT_ADDRESS_PROPERTY, endpointURL);

System.out.println("Server said: " + echo.echo(args[0]));

The drawback is that this only works when the original WSDL is still accessible. Not recommended.

Use the WSDL to get the endpoint URL

The second option is to get the endpoint URL from the WSDL.

URL newEndpoint = new URL("NEW_ENDPOINT_URL");
QName qname = new QName("http://ws.mycompany.tld","EchoService"); 

EchoService service = new EchoService(newEndpoint, qname);
Echo port = service.getEchoPort();

System.out.println("Server said: " + echo.echo(args[0]));

Git, fatal: The remote end hung up unexpectedly

In our case, the problem was a clone that wrote a .git/config file which contained a url entry that was a read only access method. Changing the url from the :// method to the @ method fixed the problem.

Running git remote -v illuminated the issue some.

How to implement history.back() in angular.js

For me, my problem was I needed to navigate back and then transition to another state. So using $window.history.back() didn't work because for some reason the transition happened before history.back() occured so I had to wrap my transition in a timeout function like so.

setTimeout(function() {
  $state.transitionTo(""); }, 100);

This fixed my issue.

Div not expanding even with content inside

Floated elements don’t take up any vertical space in their containing element.

All of your elements inside #albumhold are floated, apart from #albumhead, which doesn’t look like it’d take up much space.

However, if you add overflow: hidden; to #albumhold (or some other CSS to clear floats inside it), it will expand its height to encompass its floated children.

How to concatenate items in a list to a single string?

def eggs(someParameter):
    del spam[3]
    someParameter.insert(3, ' and cats.')

spam = ['apples', 'bananas', 'tofu', 'cats']
spam =(','.join(spam))

Postgres: SQL to list table foreign keys

I upgraded answer of @ollyc which is currently at top. I agree with @fionbio because key_column_usage and constraint_column_usage has no relative information at column level.

If constraint_column_usage has ordinal_positon column like key_column_usage, it can be joined with this column. So I made a ordinal_position to constraint_column_usage as below.

I cannot confirm this manually created ordinal_position is exactly in same order with key_column_usage. But I checked it is exactly same order at least in my case.

    ccu.table_schema AS foreign_table_schema,
    ccu.table_name AS foreign_table_name,
    ccu.column_name AS foreign_column_name
    information_schema.table_constraints AS tc 
    JOIN information_schema.key_column_usage AS kcu
      ON tc.constraint_name = kcu.constraint_name
      AND tc.table_schema = kcu.table_schema
    JOIN (select row_number() over (partition by table_schema, table_name, constraint_name order by row_num) ordinal_position,
                 table_schema, table_name, column_name, constraint_name
          from   (select row_number() over (order by 1) row_num, table_schema, table_name, column_name, constraint_name
                  from   information_schema.constraint_column_usage
                 ) t
         ) AS ccu
      ON ccu.constraint_name = tc.constraint_name
      AND ccu.table_schema = tc.table_schema
      AND ccu.ordinal_position = kcu.ordinal_position
WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_name = 'mytable'

Easiest way to toggle 2 classes in jQuery

Here's another 'non-conventional' way.

  • It implies the use of underscore or lodash.
  • It assumes a context where you:
    • the element doesn't have an init class (that means you cannot do toggleClass('a b'))
    • you have to get the class dynamically from somewhere

An example of this scenario could be buttons that has the class to be switched on another element (say tabs in a container).

// 1: define the array of switching classes:
var types = ['web','email'];

// 2: get the active class:
var type = $(mybutton).prop('class');

// 3: switch the class with the other on (say..) the container. You can guess the other by using _.without() on the array:
$mycontainer.removeClass(_.without(types, type)[0]).addClass(type);

Can one class extend two classes?

Familiar with multilevel hierarchy?

You can use subclass as superclass to your another class.

You can try this.

public class PreferenceActivity extends AbstractBillingActivity {}


public class Preferences extends PreferenceActivity {}

In this case, Preferences class inherits both PreferencesActivity and AbstractBillingActivity as well.

How to change date format from DD/MM/YYYY or MM/DD/YYYY to YYYY-MM-DD?

String dt = Date.Now.ToString("yyyy-MM-dd");

Now you got this for dt, 2010-09-09

Laravel 5 Application Key

From the line

'key' => env('APP_KEY', 'SomeRandomString'),

APP_KEY is a global environment variable that is present inside the .env file.

You can replace the application key if you trigger

php artisan key:generate

command. This will always generate the new key.

The output may be like this:

Application key [Idgz1PE3zO9iNc0E3oeH3CHDPX9MzZe3] set successfully.

Application key [base64:uynE8re8ybt2wabaBjqMwQvLczKlDSQJHCepqxmGffE=] set successfully.

Base64 encoding should be the default in Laravel 5.4

Note that when you first create your Laravel application, key:generate is automatically called.

If you change the key be aware that passwords saved with Hash::make() will no longer be valid.

is there any IE8 only css hack?

So a recent question prompted me to notice a selector set hack for excluding IE 8 only.

.selector, #excludeIE8::before {} will cause IE 8 to throw out the entire selector set, while 5-7 and 9-11 will read it just fine. Any of the :: selectors (::first-line, ::before, ::first-letter, ::selection) will work, I've merely chosen ::before so the line reads accurately. Note that the goal of the fake ::before selector is to be fake, so be sure to change it to something else if you actually have an element with the ID excludeIE8

Interestingly enough, in modern browsers (FF 45-52, GC 49-57, Edge 25/13) a bad :: selector eats the entire selector set (dabblet demo). It seems that the last Windows version of Safari (and LTE IE 7, lol) doesn't have this behavior while still understanding ::before. Additionally, I can't find anything in the spec to indicate that this is intended behavior, and since it would cause breakage on any selector set containing: ::future-legitimate-pseudoelement... I'm inclined to say this is a bug- and one that'll nibble our rears in the future.

However, if you only want something at the property level (rather than the rule level), Ziga above had the best solution via appending  \9 (the space is key; do NOT copypaste that inline as it uses an nbsp):

/*property-level hacks:*/
/*Standards, Edge*/
/*lte ie 11*/
/*lte ie 8*/
prop:val \9;
/*lte ie 7*/
/*lte ie 6*/

/*other direction...*/
/*gte ie 8, NOT Edge*/

Side note, I feel like a dirty necromancer- but I wanted somewhere to document the exclude-IE8-only selector set hack I found today, and this seemed to be the most fitting place.

Omitting all xsi and xsd namespaces when serializing an object in .NET?

XmlSerializer sr = new XmlSerializer(objectToSerialize.GetType());
TextWriter xmlWriter = new StreamWriter(filename);
XmlSerializerNamespaces namespaces = new XmlSerializerNamespaces();
namespaces.Add(string.Empty, string.Empty);
sr.Serialize(xmlWriter, objectToSerialize, namespaces);