Polymorphic associations in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Ruby on Rails

class Comment < ApplicationRecord
  belongs_to :[1], polymorphic: true
end

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

Acommentable

Bcomment

Cpostable

Dcommented

Attempts:

3 left

💡 Hint

Common Mistakes

Using the model name 'comment' instead of the polymorphic association name.

Using a non-standard association name that doesn't match other models.

The association name commentable is the conventional name used for polymorphic belongs_to in Rails.

2fill in blank

medium

Complete the code to declare a polymorphic has_many association in a Rails model.

Ruby on Rails

class Post < ApplicationRecord
  has_many :[1], as: :commentable
end

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Acommentables

Bcomments

Ccomment

Dposts

Attempts:

3 left

💡 Hint

Common Mistakes

Using singular form instead of plural for has_many.

Using a name that does not match the polymorphic association.

The has_many association should be plural and match the polymorphic association name in the related model.

3fill in blank

hard

Fix the error in the migration to create a polymorphic reference.

Ruby on Rails

create_table :comments do |t|
  t.references :[1], polymorphic: true, null: false
  t.text :content
  t.timestamps
end

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

Acommentable

Bcomment

Ccommented

Dcomments

Attempts:

3 left

💡 Hint

Common Mistakes

Using the model name 'comment' instead of the polymorphic association name.

Using plural form in the reference name.

The reference name must match the polymorphic association name, which is commentable.

4fill in blank

hard

Fill both blanks to complete the polymorphic association in the model and migration.

Ruby on Rails

class Picture < ApplicationRecord
  belongs_to :[1], polymorphic: true
end

create_table :pictures do |t|
  t.references :[2], polymorphic: true, null: false
  t.string :image_url
  t.timestamps
end

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Aimageable

Bpictureable

Cimage

Dpicture

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names in model and migration.

Using singular or plural inconsistently.

Both the model and migration must use the same polymorphic association name imageable.

5fill in blank

hard

Fill all three blanks to create a polymorphic association with validations.

Ruby on Rails

class Tag < ApplicationRecord
  belongs_to :[1], polymorphic: true

  validates :[2], presence: true
  validates :[3], presence: true
end

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

Ataggable

Btaggable_id

Ctaggable_type

Dtag

Attempts:

3 left

💡 Hint

Common Mistakes

Validating the association name instead of the foreign key and type columns.

Using incorrect column names for validations.

The polymorphic association is named taggable. The validations ensure presence of taggable_id and taggable_type, which are required for polymorphic associations.