Tutorial by Examples: g

Populate a select field depending on the value another.

This is an example to show how to change the allowed choices on a subCategory select field depending on the value of the category select field. To do that you have to make your subCategory choices dynamical for both client and server side. 1. Make the form dynamic on the client side for display / ...

symfony3 • Dynamic Forms

Keywords change the implicit receiver

When you define a class or module, the implicit receiver becomes a reference to the class itself. For example: puts "I am #{self}" class Example puts "I am #{self}" end Executing the above code will print: "I am main" "I am Example"

Ruby Language • Implicit Receivers and Understanding Self

Deploying on windows

Qt provides a deployment tool for Windows: windeployqt. The tool inspects a Qt application executable for its dependecies to Qt modules and creates a deployment directory with the necessary Qt files to run the inspected executable. A possible script may look like: set PATH=%PATH%;<qt_install_pre...

Qt • Deploying Qt applications

Installing Joomla with SSH - full cycle

Setup variables JUSERID=$[ ( $RANDOM % 100 ) + 1 ] JUSERNAME="admin" JUSEREMAIL="[email protected]" JUSERPASS="qweasd" DB="joomla_3" DBUSER="jdbuser" DBPASS="dbupass" DBPREFIX="prfx_" JOOMLAVERSION="3.6.2" ...

joomla • Full Joomla installation via SSH

basic transaction skeleton with error handling

BEGIN TRY -- start error handling BEGIN TRANSACTION; -- from here on transactions (modifictions) are not final -- start your statement(s) select 42/0 as ANSWER -- simple SQL Query with an error -- end your statement(s) COMMIT TRANSACTION; -- finalize all transa...

Microsoft SQL Server • Transaction handling

Create a Basic Page

$basic_page_args = array( 'post_title' => 'My Basic Page', 'post_content' => 'This is a basic content', 'post_type' => 'page', 'post_status' => 'publish', 'post_author' => 1 ); wp_insert_post( $basic_page_args );

WordPress • Create a Post Programmatically

Setting up testing with Gulp, Webpack, Karma and Jasmine

The first thing we need is to tell karma to use Webpack to read our tests, under a configuration we set for the webpack engine. Here, I am using babel because I write my code in ES6, you can change that for other flavors, such as Typescript. Or I use Pug (formerly Jade) templates, you don't have to....

Angular 2 • Testing an Angular 2 App

getActive() - Get active spreadsheet

This returns the currently active spreadsheet, or null if there is none. var currentSheet = SpreadsheetApp.getActive(); var url = currentSheet.getUrl(); Logger.log( url );

google-apps-script • SpreadsheetApp Active Sheet

Getting the Main Bundle

Getting a reference to the main bundle using Cocoa. To get the main bundle in Cocoa application, call the mainBundle class method of the NSBundle class. NSBundle *mainBundle; // Get the main bundle for the app; mainBundle = [NSBundle mainBundle]; Getting a reference to ...

iOS • NSBundle

Getting Bundle by Path

Locating a Cocoa bundle using its path To obtain the bundle at a specific path using Cocoa, call the bundleWithPath: class method of the NSBundle NSBundle *myBundle; // obtain a reference to a loadable bundle myBundle = [NSBundle bundleWithPath:@"/Library/MyBundle.bundle...

iOS • NSBundle

Docker stats all running containers

sudo docker stats $(sudo docker inspect -f "{{ .Name }}" $(sudo docker ps -q)) Shows live CPU usage of all running containers.

Docker • Docker stats all running containers

Reading from and writing to a file

Before reading and writing text files you should know what encoding to use. See the Perl Unicode Documentation for more details on encoding. Here we show the setting of UTF-8 as the default encoding and decoding for the function open. This is done by using the open pragma near the top of your code (...

Perl Language • File I/O (reading and writing files)

Disabling HTML Import caching

HTML Import caching will sometimes mean that changes made to HTML files that get imported do not get reflected upon browser refresh. Take the following import as an example: <link rel="import" href="./my-element.html"> If a change is done to my-element.html after previo...

polymer • Debugging

Iterating over nodes

The NodeIterator interface provides methods for iterating over nodes in a DOM tree. Given a document like this one: <html> <body> <section class="main"> <ul> <li>List Item</li> <li>List Item</li> <li>Li...

DOM • Traversal

Removing a class

Modern browsers provide a classList object to ease manipulation of the element's class attribute. Older browsers require direct manipulation of the element's className property. * Note class names are not stored in the element's property in any particular order W3C DOM4 Removing one class from an...

DOM • Manipulating a list of CSS classes

Testing for a class

Modern browsers provide a classList object to ease manipulation of the element's class attribute. Older browsers require direct manipulation of the element's className property. * Note class names are not stored in the element's property in any particular order W3C DOM4 Testing if an element cont...

DOM • Manipulating a list of CSS classes

Working with columns containg NULL values

In MySQL and other SQL dialects, NULL values have special properties. Consider the following table containing job applicants, the companies they worked for, and the date they left the company. NULL indicates that an applicant still works at the company: CREATE TABLE example (`applicant_id` INT, `...

MySQL • Dealing with sparse or missing data

Optimizing Storage Layout for InnoDB Tables

In InnoDB, having a long PRIMARY KEY (either a single column with a lengthy value, or several columns that form a long composite value) wastes a lot of disk space. The primary key value for a row is duplicated in all the secondary index records that point to the same row. Create an AUTO_INCREME...

MySQL • Mysql Performance Tips

Safe reseeding

You may want to re-seed your database without affecting your previously created seeds. For this purpose, you can use firstOrCreate in your seeder: EmployeeType::firstOrCreate([ 'type' => 'manager', ]); Then you can seed the database: php artisan db:seed Later, if you want to add a...

Laravel • Seeding

Installing Ruby with RVM

The Ruby Version Manager is a command line tool to simply install and manage different versions of Ruby. rvm istall 2.3.1 for example installs Ruby version 2.3.1 on your machine. With rvm list you can see which versions are installed and which is actually set for use. user@dev:~$ rvm li...

Ruby Language • Ruby Version Manager