Bi-directional associations inverse_of option on belongs_to side

rubyonrails-docs
1

Hi everyone, I’ve been reading the Active Record Associations guide and came across the section on Bi-directional Associations. The guide explains that we should define the inverse_of option when using non-conventional foreign keys so Rails can correctly identify the bi-directional relationship between associated models. According to Rails guide example we should define inverse_of option on has_many relation side.

class Author < ApplicationRecord
  has_many :books, inverse_of: "writer"
end

class Book < ApplicationRecord
  belongs_to :writer, class_name: "Author", foreign_key: "author_id"
end

This works perfectly fine, and Rails identifies the bi-directional association correctly.

However, in the API documentation for belongs_to, I found a note suggesting that it’s also a good idea to specify inverse_of on the belongs_to side when using the foreign_key option.

That confused me little bit and because of this, I’ve started adding inverse_of on the belongs_to side whenever I use the foreign_key option, like so:

class Author < ApplicationRecord
  has_many :books, inverse_of: "writer"
end

class Book < ApplicationRecord
  belongs_to :writer, class_name: "Author", foreign_key: "author_id", inverse_of: :books
end

So far, this has worked well for me. Do we need define it like that are should I just follow Rails Guides?