ROR - 包括的has_many和belongs_to的两端外键？ [英] ror - include foreign key at both ends of has_many and belongs_to?

问题描述

我继承code有：

 类图形＆LT;的ActiveRecord :: Base的
  的has_many：评论：foreign_key =＆GT; ASSET_ID，
  ：条件=＆GT; 'asset_type_id = 5'，
  ：为了=＆GT; 'created_at'属性，：依赖=＆GT; ：破坏

一流的注释和LT;的ActiveRecord :: Base的
  belongs_to的：图形：foreign_key =＆GT; ：ASSET_ID
 

在我看来，像的has_many不应该有foreign_key（它在belongs_to的好，我相信，引用），但我不知道，你知道吗？

即。它应该是

 类图形＆LT;的ActiveRecord :: Base的
  的has_many：评论，
  ：条件=＆GT; 'asset_type_id = 5'，
  ：为了=＆GT; 'created_at'属性，：依赖=＆GT; ：破坏

一流的注释和LT;的ActiveRecord :: Base的
  belongs_to的：图形：foreign_key =＆GT; ：ASSET_ID
 

解决方案

我认为你正在尝试做的东西是已经烤轨。您应该使用多态关联这里。

 类评论
  belongs_to的：资产，多态=＆GT;真正
结束

一流的图形
  的has_many：评论：为=＆GT; ：资产
结束
 

这样，你需要声明foreign_key对双方都不利。

I'm inheriting code which has:

class Graphic < ActiveRecord::Base
  has_many :comments, :foreign_key => 'asset_id',  
  :conditions => 'asset_type_id = 5', 
  :order => 'created_at', :dependent => :destroy

class Comment < ActiveRecord::Base
  belongs_to :graphic, :foreign_key => :asset_id

It seems to me like the has_many should not have the foreign_key (it's referenced in the belongs_to ok I believe) but I am not sure, do you know?

i.e. should it be

class Graphic < ActiveRecord::Base
  has_many :comments,  
  :conditions => 'asset_type_id = 5', 
  :order => 'created_at', :dependent => :destroy

class Comment < ActiveRecord::Base
  belongs_to :graphic, :foreign_key => :asset_id

解决方案

I think you are trying to do something that is already baked in Rails. You should use Polymorphic Associations here.

class Comment
  belongs_to :asset, :polymorphic => true
end

class Graphic
  has_many :comments, :as => :assets
end

This way, you need to declare foreign_key on neither side.

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