跨模型链的named_scopes？ （ActiveRecord的，Rails）的

Question

Class ModelA < ActiveRecord::Base
    has_many :modelb
end
Class ModelB < ActiveRecord::Base
   has_many :modelc
end
Class ModelC < ActiveRecord::Base
   has_many :modeld
   named_scope :due_on, lambda {|date| { :conditions => {:due_date => date}}}
end
Class ModelD
   named_scope :has_feature, lambda {|feature| { :conditions => {:feature => feature}}}
end

我可以做以下

a = ModelA.find(1)

a.modelb.modelc.due_on(today).modeld.has_feature(somefeature).should return_an_array_of_instances_of_ModelD

如果没有，从modela对象引用相关的modeld对象的最佳做法是什么。

Answer 1

您可能希望避免违反Demeter法则，并为其创建抽象。

即。 a.modelb.ending(today).with_feature(feature)

很高兴看到它：http://devblog.avdi.org/2011/07/05/demeter-its-not-just-a-good-idea-its-the-law/