在belongs_to关联上设置 :has_many :through 关联 Ruby on Rails

Question

我有三个模型，每个模型都有以下关联：

class Model1 < ActiveRecord::Base
  has_many :model2s
  has_many :model3s
end

class Model2 < ActiveRecord::Base
  belongs_to :model1
  has_many :model3s, :through => :model1  # will this work? is there any way around this?
end

class Model3 < ActiveRecord::Base
  belongs_to :model1
  has_many :model2s, :through => :model1  # will this work? is there any way around this?
end

正如您在评论文本中看到的，我已经提到了我需要的东西。

Answer 1

您只需创建访问它的方法

class Model2 < ActiveRecord::Base
  belongs_to :model1

  def model3s
    model1.model3s
  end
end

或者，您可以将 model3s 方法委托给 model1

class Model2 < ActiveRecord::Base
  belongs_to :model1

  delegate :model3s, :to => :model1

end

Answer 2

为什么不尝试：

class Model1 < ActiveRecord::Base
  has_many :model2s
  has_many :model3s
end

class Model2 < ActiveRecord::Base
 belongs_to :model1
 has_many   :model3s, :primary_key => :model1_id,
                      :foreign_key => :model1_id

end

class Model3 < ActiveRecord::Base
  belongs_to :model1
  has_many   :model2s, :primary_key => :model1_id,  
                       :foreign_key => :model1_id
end

这将使活动记录通过 model1_id 连接 model2 和 model3，而将 model1 完全排除在外，并且应该更高效。