What is concern folder in Rails?

If you have been building Rails applications for a while, you have likely noticed a folder called concerns . This folder gets created inside the app/controllers and app/models directories whenever you generate a new Rails application.

What is the difference between module and concern?

Essentially you create a module which you mix-in to a class. Doesn’t matter if this module extends AS::Concern, the mechanism is the same. when you write in concern that mean you are making one module. Both can be used by way include or extend into a class.

What is active support Concern Rails?

The ActiveSupport::Concern wrapper is an interesting way of encapsulating…well, certain functionality that you might be concerned with. These concerns take advantage of two directories that are automatically part of the load path within a Rails application: app/models/concerns and app/controllers/concerns .

What are scopes in Rails?

Scopes are custom queries that you define inside your Rails models with the scope method. Every scope takes two arguments: A name, which you use to call this scope in your code. A lambda, which implements the query.

What is delegate in Ruby on Rails?

delegate provides a delegate class method to easily expose contained objects’ public methods as your own. Simply say, through delegation you can use public methods in other model directly. And the name of the target object via the :to option(also a symbol or string).

What is mixin in Ruby?

Mixins in Ruby allows modules to access instance methods of another one using include method. Mixins provides a controlled way of adding functionality to classes. The code in the mixin starts to interact with code in the class. In Ruby, a code wrapped up in a module is called mixins that a class can include or extend.

What does ActiveSupport :: concern do?

ActiveSupport::Concern provides the mechanics to encapsulate a cohesive chunk of functionality into a mixin that can extend the behavior of the target class by annotating the class’ ancestor chain, annotating the class’ singleton class’ ancestor chain, and directly manipulating the target class through the included() …

What are services in Rails?

What is a service object in Rails? A service object in Rails is a plain old Ruby object created for a specific business action. It usually contains code that doesn’t fit in the model or view layer, e.g., actions via a third-party API like posting a tweet.

What is scope in Ruby?

Scope defines where in a program a variable is accessible. Ruby has four types of variable scope, local, global, instance and class. In addition, Ruby has one constant type. These are nil which is assigned to uninitialized variables and self which refers to the currently executing object.

What is scopes how should you use it Ruby?

Scoping allows you to specify commonly-used queries(it can be considered as a shortcut for long or most frequently used queries) which can be referenced as method calls on the association objects or models. With these scopes, you can use every method previously covered such as where, joins and includes.

What is alias in Ruby?

To alias a method or variable name in Ruby is to create a second name for the method or variable. Aliasing can be used either to provide more expressive options to the programmer using the class or to help override methods and change the behavior of the class or object.

Why We Use delegate in rails?

delegate provides a delegate class method to easily expose contained objects’ public methods as your own. Simply say, through delegation you can use public methods in other model directly. And the name of the target object via the :to option(also a symbol or string). …