Tutorial by Examples: s

Configuration files for rails can be found in config/environments/. By default rails has 3 environments, development, production and test. By editing each file you are editing the configuration for that environment only. Rails also has a configuration file in config/application.rb. This is a common...

Suppose you have multiple lines in the same plot, each of a different color, and you wish to make a legend to tell what each line represents. You can do this by passing on a label to each of the lines when you call plot(), e.g., the following line will be labelled "My Line 1". ax.plot(...

Database configuration of a rails project lies in a file config/database.yml. If you create a project using rails new command and don't specify a database engine to be used then rails uses sqlite as the default database. A typical database.yml file with default configuration will look similar to fol...

Callbacks offer a way to extend the functionality of a function (or method) without changing its code. This approach is often used in modules (libraries / plugins), the code of which is not supposed to be changed. Suppose we have written the following function, calculating the sum of a given array ...

You can get a Model class from a Controller name this way (context is Controller class): class MyModelController < ActionController::Base # Returns corresponding model class for this controller # @return [ActiveRecord::Base] def corresponding_model_class # ... add some validation...

Testing your Active Record models through your command line interface is simple. Navigate to the app directory in your terminal and type in rails console to start the Rails console. From here, you can run active record methods on your database. For example, if you had a database schema with a User...

Consumable Managed Products are products that can be bought multiple times such as in-game currency, game lives, power-ups, etc. In this example, we are going to implement 4 different consumable managed products "item1", "item2", "item3", "item4". Steps in...

DISCLAIMER: Scaffolding is not recommended unless it's for very conventional CRUD apps/testing. This may generate a lot of files(views/models/controllers) that are not needed in your web application thus causing headaches(bad :(). To generate a fully working scaffold for a new object, including mod...

console.count([obj]) places a counter on the object's value provided as argument. Each time this method is invoked, the counter is increased (with the exception of the empty string ''). A label together with a number is displayed in the debugging console according to the following format: [label]: ...

Debug.log's second argument is always returned, so you could write code like the following and it would just work: update : Msg -> Model -> (Model, Cmd Msg) update msg model = case Debug.log "The Message" msg of Something -> ... Replacing case msg o...

{{1,2}, {3,4}} leads to: TypeError: unhashable type: 'set' Instead, use frozenset: {frozenset({1, 2}), frozenset({3, 4})}

The Java language provides 4 operators that perform bitwise or logical operations on integer or boolean operands. The complement (~) operator is a unary operator that performs a bitwise or logical inversion of the bits of one operand; see JLS 15.15.5.. The AND (&) operator is a binary operat...

By default, all the .panel does is apply some basic border and padding to contain some content. <div class="panel panel-default"> <div class="panel-body"> Basic panel example </div> </div>

The following example can be tested on https://ellie-app.com/m9tk39VpQg/0. import Html exposing (..) import Json.Decode payload = """ ["fu", "bar"] """ main = Json.Decode.decodeString decoder payload -- Ok ["fu","b...

The following examples can be tested on https://ellie-app.com/m9vmQ8NcMc/0. import Html exposing (..) import Json.Decode payload = """ [ { "bark": true, "tag": "dog", "name": "Zap", "playful": true } , { "w...

Content scripts can be declared in manifest.json to be always injected into pages that match a set of URL patterns. Minimal example "content_scripts" : [ { "js": ["content.js"], "css": ["content.css"] "matches": [&quot...

If, instead of always having a content script injected based on the URL, you want to directly control when a content script is injected, you can use Programmatic Injection. Minimal example JavaScript chrome.tabs.executeScript({file: "content.js"}); CSS chrome.tabs.insert...

Same conditions, multiple scripts If you need to inject multiple files with all other conditions being the same, for example to include a library, you can list all of them in the "js" array: "content_scripts" : [ { "js": ["library.js", "conten...

There are two basic styles of type conversion in Go: // Simple type conversion var x := Foo{} // x is of type Foo var y := (Bar)Foo // y is of type Bar, unless Foo cannot be cast to Bar, then compile-time error occurs. // Extended type conversion var z,ok := x.(Bar) // z is of type Bar, o...

As Go uses implicit interface implementation, you will not get a compile-time error if your struct does not implement an interface you had intended to implement. You can test the implementation explicitly using type casting: type MyInterface interface { Thing() } type MyImplementer struct {} ...