What is active support concern?
ActiveSupport’s Concern module allows us to mix in callbacks, class and instance methods, and create associations on target objects. This module has an included method, which takes a block, as well as an append_features method and class_methods block, which you can read about in the source code.
What is the reason for using concern in rails?
According to the Rails docs, we want to encapsulate the code in a different module to reuse that code in different places when that same functionality is needed. We use concerns when we feel that one file is overwhelmed with the functionality, so we extract some part of the code and save it into another file or module.
What is the difference between extend and include in Ruby?
In simple words, the difference between include and extend is that ‘include’ is for adding methods only to an instance of a class and ‘extend’ is for adding methods to the class but not to its instance.
What is prepend in Ruby?
Available since Ruby 2, prepend is a bit less known to Rubyists than its two other friends. It actually works like include, except that instead of inserting the module between the class and its superclass in the chain, it will insert it at the bottom of the chain, even before the class itself.
How do you call a concern in Rails?
To use this concern, you include the module as usual. For example, if the Post model wanted the visibility functionality, it would include the Visible concern. Including this concern adds the visible_to attribute, is_visible instance method, and the count_all_visible class method to the Post class.
What are services 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 credentials Yml ENC?
credentials. yml. enc – This is an encrypted file that stores all the credentials. It is a YAML file that is encrypted by using the master key. Since this is encrypted, it is safe to push this file to the remote repository.
Can modules inherit Ruby?
The Ruby class Class inherits from Module and adds things like instantiation, properties, etc – all things you would normally think a class would have. Because Module is literally an ancestor of Class , this means Modules can be treated like classes in some ways.
What is difference between load and require in Ruby?
You should use load function mainly for the purpose of loading code from other files that are being dynamically changed so as to get updated code every time. Require reads the file from the file system, parses it, saves to the memory, and runs it in a given place.
What is super in Ruby?
Ruby uses the super keyword to call the superclass implementation of the current method. Within the body of a method, calls to super acts just like a call to that original method. The search for a method body starts in the superclass of the object that was found to contain the original method.
What is inject in Ruby?
Inject applies the block result + element. to each item in the array. For the next item (“element”), the value returned from the block is “result”. The way you’ve called it (with a parameter), “result” starts with the value of that parameter. So the effect is adding the elements up.
What is ActiveSupport :: concern in Rails?
A Rails Concern is a module that extends the ActiveSupport::Concern module. Concerns allow us to include modules with methods (both instance and class) and constants into a class so that the including class can use them.
What are modules in Rails?
Modules provide a structure to collect Ruby classes, methods, and constants into a single, separately named and defined unit. This is useful so you can avoid clashes with existing classes, methods, and constants, and also so that you can add (mix in) the functionality of modules into your classes.
What are Initializers in Rails?
An initializer is any file of ruby code stored under /config/initializers in your application. You can use initializers to hold configuration settings that should be made after all of the frameworks and plugins are loaded.
How do I open a credential file?
To open Credential Manager, type credential manager in the search box on the taskbar and select Credential Manager Control panel. Select Web Credentials or Windows Credentials to access the credentials you want to manage.
How do you add credentials in rails?
Rails for Beginners Part 23: Rails Credentials – YouTube
What is multiple inheritance in OOP?
Multiple inheritance is a feature of some object-oriented computer programming languages in which an object or class can inherit features from more than one parent object or parent class. It is distinct from single inheritance, where an object or class may only inherit from one particular object or class.
What is difference between class and module in Ruby?
What is the difference between a class and a module? Modules are collections of methods and constants. They cannot generate instances. Classes may generate instances (objects), and have per-instance state (instance variables).
What is difference between include and require?
Use require when the file is required by the application. Use include when the file is not required and application should continue when file is not found.
What is the difference between modules and classes in Ruby?
What is self in Ruby?
self is a reserved keyword in Ruby that always refers to the current object and classes are also objects, but the object self refers to frequently changes based on the situation or context. So if you’re in an instance, self refers to the instance. If you’re in a class, self refers to that class.
What is the difference between calling super and calling super ()?
When you call super with no arguments, Ruby sends a message to the parent of the current object, asking it to invoke a method with the same name as where you called super from, along with the arguments that were passed to that method. On the other hand, when called with super() , it sends no arguments to the parent.
What is splat in Ruby?
Parameter with splat operator (*) in Ruby (part 1/2)
A parameter with the splat operator allows us to work with an undefined number of arguments. A parameter with the splat operator takes only those arguments for which there were no other parameters. A parameter with the splat operator is optional.
What does :+ mean in Ruby?
inject(:+) is not Symbol#to_proc, :+ has no special meaning in the ruby language – it’s just a symbol.
What is polymorphic association in Rails?
Polymorphic relationship in Rails refers to a type of Active Record association. This concept is used to attach a model to another model that can be of a different type by only having to define one association.