Xcode Master Detail应用程序后退按钮属性(Xcode Master Detail Application back button properties)

 一个简单的方法就是在模型中有以下关系 
 
belongs_to :master_product, :foreign_key => : master_prouduct_id, :class_name => "Product"
 
 通过在任何产品对象上调用master_product，我们可以获得主对象。 
 
 但是这种实现需要应用程序逻辑来处理是否调用master_product。 
 
 别担心，我们可以按照下面的其他方式， 
 
Product < AR::Base
    def self.find(id)
        rec = super(id)
        rec.master_product_id ? super(rec.master_product_id) : rec
    end
end
 
 但是，这样我们就不会使用find来获得儿童产品，即使我们也希望获得儿童产品。 所以，我建议为此使用不同的函数名称，或者在查找定义中有一个标志，它自己告诉要求。 
 
 仍然，您需要处理其他方案（Where，Joins，Associations等）。 
 
 我不确定rails是否对此有任何支持。 

one simple way you can do is, having following relation in model
 
belongs_to :master_product, :foreign_key => : master_prouduct_id, :class_name => "Product"
 
by calling master_product on any product object we can get master object.
 
But this implementation needs application logic to handle whether to call master_product or not.
 
Don't worry, we can follow other way as below,
 
Product < AR::Base
    def self.find(id)
        rec = super(id)
        rec.master_product_id ? super(rec.master_product_id) : rec
    end
end
 
But, In this way we wont get the child products at all using find, even if we want to get child products also. So, i suggest to use different function name for this or have a flag in find definition it self to tell the requirement.
 
Still, You need to handle other scenarios(Where, Joins, Associations etc).
 
Iam not sure whether rails had any support for this.