CODEWITHSUNDEEP
ruby-on-railsactiverecordruby-on-rails-4
Jeff
Jeff

Reputation: 14279

Getting all records two `has_many, through` relationships away

I have a couple models

class AAA < ActiveRecord::Base
  has_many :bbbs, through: :some_other_model
end

class BBB < ActiveRecord::Base
  has_many :cccs, through: :yet_another_model
end

Assuming I have a reference to an instance of AAA, how can I get a flat list of all CCCs without resorting to inefficient patterns like a.bbbs.map { |x| x.cccs }?

Upvotes: 0

Views: 76

Answers (1)

mechanicalfish
mechanicalfish

Reputation: 12836

Since RoR 3.1 you can nest has_many :through associations.

From 3.1 release notes:

Associations with a :through option can now use any association as the through or source association, including other associations which have a :through option and has_and_belongs_to_many associations.

In your example:

class AAA < ActiveRecord::Base
  has_many :bbbs, through: :some_other_model
  has_many :cccs, through: :bbbs
end

AAA.first.cccs # => [ccc1, ccc2, ...]

Upvotes: 2

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