Eager loading (N+1 prevention) in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to eager load the associated posts for users.

Ruby on Rails

users = User.[1](:posts)

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

Awhere

Bjoins

Cselect

Dincludes

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'joins' instead of 'includes' causes N+1 queries.

Using 'select' does not load associations.

Using includes loads the associated posts in one query to prevent N+1 queries.

2fill in blank

medium

Complete the code to eager load comments for posts.

Ruby on Rails

posts = Post.[1](:comments)

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

Aincludes

Bwhere

Corder

Dgroup

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'where' filters records but does not eager load.

Using 'order' or 'group' does not load associations.

includes loads the comments with posts to prevent multiple queries.

3fill in blank

hard

Fix the error in the code to eager load authors for articles.

Ruby on Rails

articles = Article.[1](:author)

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

Aincludes

Bpluck

Cfind

Dload

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'load' or 'find' does not eager load associations.

Using 'pluck' only selects columns, no associations.

includes is the correct method to eager load the author association.

4fill in blank

hard

Fill both blanks to eager load comments and their authors for posts.

Ruby on Rails

posts = Post.[1]([2]: :author)

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

Aincludes

Bjoins

Ccomments

Dwhere

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'joins' instead of 'includes' causes N+1 queries.

Using 'where' does not eager load associations.

Use includes with nested association comments: :author to eager load both.

5fill in blank

hard

Fill all three blanks to eager load categories, tags, and their creators for articles.

Ruby on Rails

articles = Article.[1]([2], [3]: :creator)

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

Aincludes

Bcategories

Ctags

Djoins

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'joins' instead of 'includes' causes multiple queries.

Not nesting the creator association under tags.

Use includes with :categories and nested :tags => :creator to eager load all associations.