Tutorial by Examples: o

If you want to display to your users meaningful errors instead of simple "sorry, something went wrong", Rails has a nice utility for the purpose. Open the file app/controllers/application_controller.rb and you should find something like this: class ApplicationController < ActionContro...

If you ever wanted to determine the html content to be printed on a page during run time then, rails has a very good solution for that. It has something called the content_for which allows us to pass a block to a rails view. Please check the below example, Declare content_for <div> <%=...

Accessibility of symbols declared in a module can be controlled using private and public attributes and statement. Syntax of the statement form: !all symbols declared in the module are private by default private !all symbols declared in the module are public by default public !symbols in t...

You can rollback and then migrate again using the redo command. This is basically a shortcut that combines rollback and migrate tasks. Run command: 5.0 rake db:migrate:redo 5.0 rails db:migrate:redo You can use the STEP parameter to go back more than one version. For example, to go ba...

The border-radius property allows you to change the shape of the basic box model. Every corner of an element can have up to two values, for the vertical and horizontal radius of that corner (for a maximum of 8 values). The first set of values defines the horizontal radius. The optional second ...

The border-style property sets the style of an element's border. This property can have from one to four values (for every side of the element one value.) Examples: border-style: dotted; border-style: dotted solid double dashed; border-style can also have the values none and hidden. They ...

It is possible to limit the tests executed by manage.py test by specifying which modules should be discovered by the test runner: # Run only tests for the app names "app1" $ python manage.py test app1 # If you split the tests file into a module with several tests files for an app $ p...

Drupal Console The new CLI for Drupal. A tool to generate boilerplate code, interact with and debug Drupal. First, we need to install Drupal Console. Drupal Console is needed not only for this time, but for future installations. # Run this in your terminal to get the latest project version: cur...

<PROJECT_ROOT>\app\build.gradle is specific for app module. <PROJECT_ROOT>\build.gradle is a "Top-level build file" where you can add configuration options common to all sub-projects/modules. If you use another module in your project, as a local library you would have another...

/** * The buildscript {} block is where you configure the repositories and * dependencies for Gradle itself--meaning, you should not include dependencies * for your modules here. For example, this block includes the Android plugin for * Gradle as a dependency because it provides the addition...

/** * The first line in the build configuration applies the Android plugin for * Gradle to this build and makes the android {} block available to specify * Android-specific build options. */ apply plugin: 'com.android.application' /** * The android {} block is where you configure all...

You can define the signing configuration to sign the apk in the build.gradle file using these properties: storeFile : the keystore file storePassword: the keystore password keyAlias: a key alias name keyPassword: A key alias password In many case you may need to avoid this kind of info in ...

Looping over an iterable defined inside of your viewmodel or passed through as a bindable (if a Custom Attribute or Custom Element) can be done like so. An array of string values export class MyViewModel { myIterable = ['String 1', 'String 2', 'String 3', 'String 4']; } <template> ...

import pandas as pd import numpy as np np.random.seed(0) rng = pd.date_range('2015-02-24', periods=10, freq='T') df = pd.DataFrame({'Val' : np.random.randn(len(rng))}, index=rng) print (df) Val 2015-02-24 00:00:00 1.764052 2015-02-24 00:01:00 0.400157 2015-02...

Each pair in the dictionary is an instance of KeyValuePair with the same type parameters as the Dictionary. When you loop through the dictionary with For Each, each iteration will give you one of the Key-Value Pairs stored in the dictionary. For Each kvp As KeyValuePair(Of String, String) In curren...

Dim extensions As New Dictionary(Of String, String) _ from { { "txt", "notepad" }, { "bmp", "paint" }, { "doc", "winword" } } This creates a dictionary and immediately fills it with three KeyValuePairs. You can also add new val...

When you want to allow only certain keys in your arrays, especially when the array comes from request parameters, you can use array_intersect_key together with array_flip. $parameters = ['foo' => 'bar', 'bar' => 'baz', 'boo' => 'bam']; $allowedKeys = ['foo', 'bar']; $filteredParameters =...

Dictionaries are implemented in a Dict core library. A dictionary mapping unique keys to values. The keys can be any comparable type. This includes Int, Float, Time, Char, String, and tuples or lists of comparable types. Insert, remove, and query operations all take O(log n) time. Unlike Tu...

Comparable types are primitive types that can be compared using comparison operators from Basics module, like: (<), (>), (<=), (>=), max, min, compare Comparable types in Elm are Int, Float, Time, Char, String, and tuples or lists of comparable types. In documentation or type definitio...

Record is a set of key-value pairs. greeter = { isMorning: True , greeting: "Good morning!" } It is impossible to access a value by an non-existent key. It is impossible to dynamically modify Record's structure. Records only allow you to update values by constant keys....