has_one relationship in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Ruby on Rails

class User < ApplicationRecord
  [1] :profile
end

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

Abelongs_to

Bhas_one

Chas_many

Dhas_and_belongs_to_many

Attempts:

3 left

💡 Hint

Common Mistakes

Using belongs_to instead of has_one here.

Using has_many which is for multiple related objects.

The has_one method declares a one-to-one association from the User model to the Profile model.

2fill in blank

medium

Complete the code to declare the inverse belongs_to association in the related model.

Ruby on Rails

class Profile < ApplicationRecord
  [1] :user
end

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

Ahas_one

Bhas_many

Cbelongs_to

Dhas_and_belongs_to_many

Attempts:

3 left

💡 Hint

Common Mistakes

Using has_one here instead of belongs_to.

Using has_many which is for multiple related objects.

The belongs_to method declares the association from Profile back to User, indicating Profile belongs to one User.

3fill in blank

hard

Fix the error in the has_one declaration to specify the class name correctly.

Ruby on Rails

class User < ApplicationRecord
  has_one :[1], class_name: 'UserProfile'
end

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

Auserprofiles

Bprofiles

Cuser_profile

Dprofile

Attempts:

3 left

💡 Hint

Common Mistakes

Using plural form like 'profiles' for has_one.

Using underscored or concatenated names that don't match the model.

The association name should be singular and match the related model logically. 'profile' is correct here.

4fill in blank

hard

Fill both blanks to complete the has_one association with dependent destroy option.

Ruby on Rails

class User < ApplicationRecord
  [1] :profile, [2]: :destroy
end

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

Ahas_one

Bdependent

Cbelongs_to

Doptional

Attempts:

3 left

💡 Hint

Common Mistakes

Using belongs_to instead of has_one for the association.

Using optional instead of dependent for the option.

has_one declares the association, and dependent: :destroy ensures the related profile is deleted when the user is deleted.

5fill in blank

hard

Fill all three blanks to complete a has_one association with class name and foreign key options.

Ruby on Rails

class User < ApplicationRecord
  [1] :profile, class_name: '[2]', foreign_key: '[3]'
end

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

Ahas_one

BUserProfile

Cuser_id

Dbelongs_to

Attempts:

3 left

💡 Hint

Common Mistakes

Using belongs_to instead of has_one for the association.

Incorrect class name spelling or casing.

Wrong foreign key name that doesn't match the database column.

has_one declares the association. class_name specifies the related model name. foreign_key tells Rails which column links the models.