Tutorial by Examples: u

Pagination by passing parmeter with custom query in spring data JPA

I use Spring Boot 1.4.4.RELEASE , with MySQL as the Database and Spring Data JPA abstraction to work with MySQL. Indeed ,it is the Spring Data JPA module that makes it so easy to set up Pagination in a Spring boot app in the first place. Scenario expose an endpoint /students/classroom/{id} . It wi...

spring-data • Pagination with Spring Data

Looking before you leap with processor-intensive function

A program can easily waste time by calling a processor-intensive function multiple times. For example, take a function which looks like this: it returns an integer if the input value can produce one, else None: def intensive_f(value): # int -> Optional[int] # complex, and time-consuming cod...

Python Language • Python Anti-Patterns

Custom inheritance column

By default STI model class name is stored in a column named type. But its name can be changed by overriding inheritance_column value in a base class. E.g.: class User < ActiveRecord::Base self.inheritance_column = :entity_type # can be string as well end class Admin < User; end Migr...

Ruby on Rails • Single Table Inheritance

Rails model with type column and without STI

Having type column in a Rails model without invoking STI can be achieved by assigning :_type_disabled to inheritance_column: class User < ActiveRecord::Base self.inheritance_column = :_type_disabled end

Ruby on Rails • Single Table Inheritance

Custom mix task with command line arguments

In a basic implementation the task module must define a run/1 function that takes a list of arguments. E.g. def run(args) do ... end defmodule Mix.Tasks.Example_Task do use Mix.Task @shortdoc "Example_Task prints hello + its arguments" def run(args) do IO.puts "Hello ...

Elixir Language • Mix

Setup perlbrew for the first time

Create setup script ~/.perlbrew.sh: # Reset any environment variables that could confuse `perlbrew`: export PERL_LOCAL_LIB_ROOT= export PERL_MB_OPT= export PERL_MM_OPT= # decide where you want to install perlbrew: export PERLBREW_ROOT=~/perlbrew [[ -f "$PERLBREW_ROOT/etc/bashrc" ]...

Perl Language • Perlbrew

Set up the Project

We'll assume you're doing this in Visual Studio 2015 (VS 2015 Community, in my case). Create an empty Console project in VS. In Project | Properties change the Output Type to Windows Application. Next, use NuGet to add FsXaml.Wpf to the project; this package was created by the estimable Reed Cop...

F# • Using F#, WPF, FsXaml, a Menu, and a Dialog Box

Add the "Business Logic"

Presumably, your program will do something. Add your working code to the project in place of Program.fs. In this case, our task is to draw spirograph curves on a Window Canvas. This is accomplished using Spirograph.fs, below. namespace Spirograph // open System.Windows does not automatically o...

F# • Using F#, WPF, FsXaml, a Menu, and a Dialog Box

Installing an unlisted package

By unlisted package, I mean a package that is not available through Package Control (yet). So, you can't find it in packagecontrol.io. BUT, you can still install it using Package Control, so you'll get all the advantages. For example, they'll be automatically updated, just like a "regular&quot...

sublimetext3 • Package Control

Version Numbers

As of Salt version 2014.1.0, Salt uses a date based system for version numbers. Version numbers are in the format YYYY.MM.R. The year (YYYY) and month (MM) indicate when the release was created. The bugfix release number (R) increments within that feature release. In order to distinguish future rel...

salt-stack • Getting started with salt-stack

Defining and using a plugin

package main import "fmt" var V int func F() { fmt.Printf("Hello, number %d\n", V) } This can be built with: go build -buildmode=plugin And then loaded and used from your application: p, err := plugin.Open("plugin_name.so") if err != nil { panic(e...

Go • Plugin

HTTP GET request and looping through data

The following example shows how a set of data obtained from a remote source can be rendered into a component. We make an AJAX request using fetch, which is build into most browsers. Use a fetch polyfill in production to support older browsers. You can also use any other library for making requests ...

React • React AJAX call

Move a date a number of months consistently by months

Let's say we want to move a given date a numof months. We can define the following function, that uses the mondate package: moveNumOfMonths <- function(date, num) { as.Date(mondate(date) + num) } It moves consistently the month part of the date and adjusting the day, in case the date re...

R Language • Date and Time

List running service on Ubuntu

To get a list of the service on your system, you may run: service --status-all The output of service --status-all lists the state of services controlled by System V. The + indicates the service is running, - indicates a stopped service. You can see this by running service SERVICENAME status for...

GNU/Linux • Services

Scaffolding a New Angular CLI Project

ng new NewProject or ng init NewProject

Angular 2 • Brute Force Upgrading

Flexbox Introduction

The Flexbox (Flexible box) layout, introduced in CSS3 provides a more efficient way to lay out, align and distribute space among children elements(flex items) within a container element(flex container). Most importantly even when their sizes are unknown or dynamic and hence the term "flex"...

flexbox • Getting started with flexbox