Rails 3 - 从相关模型中获取和排序模型的对象

Question

我有两个模型，教师和教师领袖：

#  id        :integer
#  last_name :string(255)
class Teacher < ActiveRecord::Base 
  has_one :teacher_leader
end

#  teacher_id :integer
class TeacherLeader < ActiveRecord::Base  
  belongs_to :teacher
end

我想让所有老师领导的老师通过last_name对他们进行排序。我怎么能这样做？

Answer 1

Teacher.joins(:teacher_leader).uniq.order(:last_name)