includes(*args) public

Specify relationships to be included in the result set. For example:

users = User.includes(:address)
users.each do |user|

allows you to access the address attribute of the User model without firing an additional query. This will often result in a performance improvement over a simple join.


If you want to add conditions to your included models you’ll have to explicitly reference them. For example:

User.includes(:posts).where('posts.name = ?', 'example')

Will throw an error, but this will work:

User.includes(:posts).where('posts.name = ?', 'example').references(:posts)
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