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[英]Rails has_many association through a belongs_to polymorphic association
[英]Setting a :has_many :through association on a belongs_to association Ruby on Rails
我有三个模型,每个模型具有以下关联:
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所看到的,我已经提到了我所需要的。
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
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
这将通过model1_id具有活动记录联接model2和model3,而将model1完全排除在模型之外,并且应该更有效。
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