ActiveRecord includes. Specify included columns

Question

I have model Profile. Profile has_one User. User model has field email. When I call

Profile.some_scope.includes(:user)

it calls

<         


        

Answer 1

You need extra belongs to in the model.

For simple association:

belongs_to :user_restricted, -> { select(:id, :email) }, class_name: 'User'

For Polymorphic association (for example, :commentable):

belongs_to :commentable_restricted, -> { select(:id, :title) }, polymorphic: true, foreign_type: :commentable_type, foreign_key: :commentable_id

You can choose whatever belongs_to name you want. For the examples given above, you can use them like Article.featured.includes(:user_restricted), Comment.recent.includes(:commentable_restricted) etc.