Rails order by associated data

问题

Is it possible to order the results of school.classrooms by the teacher's name? I want to do this directly in the association, and not a separate call.

class School < ActiveRecord::Base
  has_many :classrooms
end


class Classroom < ActiveRecord::Base
  belongs_to :school
  belongs_to :teacher
end


class Teacher < ActiveRecord::Base
  has_one :classroom
end

回答1:

This should work if you are using rails 3.x

school.classrooms.includes(:teacher).order("teachers.name")

来源：https://stackoverflow.com/questions/8875184/rails-order-by-associated-data