belongs_to relationship in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a belongs_to association in a Rails model.

Ruby on Rails

class Comment < ApplicationRecord
  [1] :post
end

Drag options to blanks, or click blank then click option'

Abelongs_with

Bbelongs_to

Chas_one

Dhas_many

Attempts:

3 left

💡 Hint

Common Mistakes

Using has_many instead of belongs_to

Using belongs_with which is not a valid Rails method

The belongs_to method sets up a one-to-one connection with another model, indicating that each comment belongs to a single post.

2fill in blank

medium

Complete the code to add a foreign key column for the belongs_to association in a Rails migration.

Ruby on Rails

class AddPostRefToComments < ActiveRecord::Migration[7.0]
  def change
    add_reference :comments, :[1], foreign_key: true
  end
end

Drag options to blanks, or click blank then click option'

Acomment

Buser

Carticle

Dpost

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong model name for the foreign key

Forgetting to add foreign_key: true

The foreign key column should match the associated model name, which is post in this case.

3fill in blank

hard

Fix the error in the belongs_to association declaration.

Ruby on Rails

class Order < ApplicationRecord
  [1] :customer, optional: true
end

Drag options to blanks, or click blank then click option'

Abelongs_to

Bhas_many

Cbelongs

Dhas_one

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'belongs' instead of 'belongs_to'

Using 'has_many' which is for collections

The correct method to declare the association is belongs_to. The option optional: true allows the association to be nil.

4fill in blank

hard

Fill both blanks to complete the belongs_to association with a custom class name and foreign key.

Ruby on Rails

class Review < ApplicationRecord
  belongs_to :[1], class_name: '[2]', foreign_key: 'author_id'
end

Drag options to blanks, or click blank then click option'

Aauthor

Buser

CAuthor

DPost

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase for class_name

Mixing up association name and class name

The association name is author, and the class name must be the exact model name 'Author' as a string.

5fill in blank

hard

Fill all three blanks to complete a belongs_to association with a polymorphic interface.

Ruby on Rails

class Picture < ApplicationRecord
  belongs_to :[1], polymorphic: [2], optional: [3]
end

Drag options to blanks, or click blank then click option'

Aimageable

Btrue

C:true

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using string 'true' instead of boolean true

Using string 'false' instead of boolean false

Wrong association name

The association name is imageable. The polymorphic option expects a boolean true. The optional option is a boolean false here.