How do you create a many-to-many relationship in rails?

In Rails, there are two main ways of creating many-to-many relationships between models:

1. using a has_and_belongs_to_many association.
2. using has_many :through association.

What is the difference between Has_one and Belongs_to?

They essentially do the same thing, the only difference is what side of the relationship you are on. If a User has a Profile , then in the User class you’d have has_one :profile and in the Profile class you’d have belongs_to :user .

Does Ruby have many relationships in Rails?

Many-to-many is one of the most common relationship in Rails(database). The concept is simple. When both 2 models have has_many association to each other, we say they are many-to-many relationship.

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.

What does @variable mean in Ruby?

This means that only one variable value exists for all objects instantiated from this class. If one object instance changes the value of the variable, that new value will essentially change for all other object instances.

What is Has_many in Ruby on Rails?

A has_many association indicates a one-to-many connection with another model. This association generally is located on the other side of a belongs_to association. This association indicates that each instance of the model has zero or more instances of another model.

Does rails have one relationship?

A has_one association indicates that one other model has a reference to this model. That model can be fetched through this association. This relation can be bi-directional when used in combination with belongs_to on the other model.

Does Association have one rails?

Ruby on Rails ActiveRecord Associations has_one This association indicates that each instance of a model contains or possesses one instance of another model. In Active Record, when you have a has_one relation, active record ensures that the only one record exists with the foreign key.

What does dependent destroy do rails?

If you set the :dependent option to: :destroy, when the object is destroyed, destroy will be called on its associated objects. :delete, when the object is destroyed, all its associated objects will be deleted directly from the database without calling their destroy method.

What is Attr_accessor in Ruby?

Nouman Abbasi. In Ruby, object methods are public by default, while data is private. To access and modify data, we use the attr_reader and attr_writer . attr_accessor is a shortcut method when you need both attr_reader and attr_writer .

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.

How to make many-to-many relationships work in Rails 3?

Basically there two approaches to make many-to-many work, either has_and_belongs_to_many or has_many :through (recommended). Show activity on this post. In Rails 3 you want to make a join table for many to many relationships, using the plural names of the tables you want to join in alphabetical order. So in this case it would be groups_users.

What’s in your rails app folder?

Most of the work in this tutorial will happen in the app folder, but here’s a basic rundown on the function of each of the files and folders that Rails creates by default: Contains the controllers, models, views, helpers, mailers, channels, jobs, and assets for your application.

How to join many to many relationships in a table?

In Rails 3 you want to make a join table for many to many relationships, using the plural names of the tables you want to join in alphabetical order. So in this case it would be groups_users. Show activity on this post.

How do I check if my Rails application is running?

To see your application in action, open a browser window and navigate to http://localhost:3000. You should see the Rails default information page: When you want to stop the web server, hit Ctrl+C in the terminal window where it’s running.