Association callbacks in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a callback that runs after a comment is created.

Ruby on Rails

class Comment < ApplicationRecord
  belongs_to :post
  after_[1] :notify_post_author

  def notify_post_author
    # notification logic here
  end
end

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

Asave

Bcreate

Cupdate

Ddestroy

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'after_save' which runs on both create and update, not just creation.

Using 'after_destroy' which runs after deletion, not creation.

The 'after_create' callback runs only after a new record is created, which is suitable for notifying after a comment is added.

2fill in blank

medium

Complete the code to run a callback before a post is destroyed to clean up associated comments.

Ruby on Rails

class Post < ApplicationRecord
  has_many :comments, dependent: :destroy
  before_[1] :cleanup_comments

  def cleanup_comments
    comments.destroy_all
  end
end

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Asave

Bupdate

Ccreate

Ddestroy

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'before_save' which runs on create and update, not on destroy.

Using 'after_destroy' which runs after deletion, too late for cleanup.

The 'before_destroy' callback runs before the post is deleted, allowing cleanup of associated comments.

3fill in blank

hard

Fix the error in the callback method name to correctly run after a post's comments are added.

Ruby on Rails

class Post < ApplicationRecord
  has_many :comments, after_add: :[1]

  def log_comment_addition(comment)
    # log logic here
  end
end

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Alog_comment_addition

Blog_comment_added

Clog_comment_add

Dlog_added_comment

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method name that does not match the callback symbol.

Misnaming the callback method causing it not to run.

The 'after_add' callback for the comments association runs after a comment is added. The method receives the added comment as an argument. The method name must match the symbol passed.

4fill in blank

hard

Fill both blanks to define a callback that runs before adding a tag to a post and calls the correct method.

Ruby on Rails

class Post < ApplicationRecord
  has_many :tags, [1]: :[2]

  def check_tag_limit(tag)
    # limit check logic
  end
end

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Abefore_add

Bafter_add

Ccheck_tag_limit

Dvalidate_tag_limit

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'after_add' instead of 'before_add' for pre-add checks.

Mismatching method names causing callbacks not to trigger.

The 'before_add' callback for the tags association runs before a tag is added, and the method 'check_tag_limit' (receiving the tag) is the correct handler.

5fill in blank

hard

Fill all three blanks to define callbacks that run before adding and after removing categories from a product.

Ruby on Rails

class Product < ApplicationRecord
  has_many :categories, [1]: :[2], [3]: :log_category_removal

  def log_category_addition(category)
    # log addition
  end
end

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

Abefore_add

Blog_category_addition

Cafter_remove

Dbefore_remove

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'before_remove' instead of 'after_remove' for post-removal actions.

Mismatching method names causing callbacks not to execute.

The 'before_add' callback for the categories association runs before adding a category and calls 'log_category_addition(category)'. The 'after_remove' callback runs after removing a category and calls 'log_category_removal(category)'.