自我指涉的has_many：通过与定制：主键的问题 [英] Self-referential has_many :through with customized :primary key issue

问题描述

我试图效仿Twitter的模式在我的Rails 2.3.8应用程序（红宝石1.8.7）

I'm trying to emulate the twitter model in my Rails 2.3.8 app (ruby 1.8.7)

class Connection < ActiveRecord::Base
  belongs_to :subject, :foreign_key => 'subject_id', :primary_key => 'user_id', :class_name => 'User'
  belongs_to :follower, :foreign_key => 'follower_id', :primary_key => 'user_id', :class_name => 'User'
end

class User < ActiveRecord::Base
  has_many :relations_to, :primary_key => 'user_id', :foreign_key => 'follower_id', :class_name => 'Connection'
  has_many :relations_from, :primary_key => 'user_id', :foreign_key => 'subject_id', :class_name => 'Connection'
  has_many :linked_from, :through => :relations_from, :source => :subject, :primary_key => 'user_id'
  has_many :linked_to, :through => :relations_to, :source => :follower, :primary_key => 'user_id'
end

这给了我一个SystemStackError：堆栈层次过深的错误，当我做User.first.linked_from。我之所以要使用：USER_ID代替标准号是因为我的主键必须是一个字符串

This gives me a "SystemStackError: stack level too deep" error when I do User.first.linked_from. The reason I have to use :user_id instead of the standard id is because my primary key has to be a string.

我能做些什么使关系的工作，这样我可以做User.first.linked_from和User.first.linked_to？

What can I do to make the relation work, so that I can do User.first.linked_from and User.first.linked_to?

推荐答案

我相信它应该是这样的：

I believe it should be like this:

class Connection < ActiveRecord::Base
  belongs_to :subject, :class_name => 'User'
  belongs_to :follower, :class_name => 'User'
end

class User < ActiveRecord::Base
  set_primary_key "user_id"

  has_many :relations_to, :foreign_key => 'follower_id', :class_name => 'Connection'
  has_many :relations_from, :foreign_key => 'subject_id', :class_name => 'Connection'
  has_many :linked_from, :through => :relations_from, :source => :follow 
  has_many :linked_to, :through => :relations_to, :source => :subject
end

而我删除了一些东西，它看起来像你的：源=＆GT; ：遵循和：源=＆GT; ：受进行切换，并创建了一个循环引用

while I removed a few things, it looks like your :source => :follow and :source => :subject were switched and it created a circular reference.

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