Ruby on Rails的HAS_MANY：通过协会，与同型号的两列 [英] ruby on rails has_many :through association which has two columns with same model

问题描述

我有以下型号：

class UserShareTag < ActiveRecord::Base
  attr_protected :sharee_id, :post_id, :sharer_id

  belongs_to :sharer, :class_name => "User"
  belongs_to :post
  belongs_to :sharee, :class_name => "User"

  validates :sharer_id, :presence => true
  validates :sharee_id, :presence => true
  validates :post_id, :presence => true
end

在Post模型，我有以下行：

In the Post model, I have the following line:

has_many :user_share_tags, :dependent => :destroy
has_many :user_sharers, :through => :user_share_tags, :uniq => true, :class_name => "User"
has_many :user_sharees, :through => :user_share_tags, :uniq => true, :class_name => "User"

我如何传达：user_sharers应符合下列条件：sharer_id？和：user_sharees应该对应于：sharee_id？由于它们两者是相同的用户模型，我不知该怎么办。

How do I convey that :user_sharers should correspond to :sharer_id? and :user_sharees should correspond to :sharee_id? Since they both are the same User model, I am unsure what to do.

有些相关的问题 - 在用户模式，我有：

Somewhat related problem - in the User model I have:

has_many :user_share_tags, :dependent => :destroy
has_many :user_shared_posts, :through => :user_share_tags, :uniq => true, :class_name => "Post"
has_many :recommended_posts, :through => :user_share_tags, :uniq => true, :class_name => "Post"

我如何合并的附加逻辑：user_shared_posts应该包含的职位，其中：sharer_id是USER_ID？和：recommended_posts应该包含的职位，其中：sharee_id是USER_ID

How do I incorporate the additional logic that :user_shared_posts should contain the posts where the :sharer_id is the user_id? and :recommended_posts should contain the posts where the :sharee_id is the user_id?

在此先感谢！

推荐答案

您只需要一个补充：源参数到你的的has_many 协会（你不需要：CLASS_NAME 选项）：

You just need to add a :source parameter to your has_many associations (and you don't need the :class_name option):

has_many :user_sharers, :through => :user_share_tags, :source => :sharer, :uniq => true, :class_name => "User"
has_many :user_sharers, :through => :user_share_tags, :source => :sharee, :uniq => true, :class_name => "User"

然后在你的用户模型，需要一个额外的的has_many 关联：

Then in your User model, you need an extra has_many association:

has_many :user_share_tags_as_sharee, :class_name => "UserShareTag", :foreign_key => :sharee_id, :dependent => :destroy
has_many :user_share_tags_as_sharer, :class_name => "UserShareTag", :foreign_key => :sharer_id, :dependent => :destroy
has_many :user_shared_posts, :source => :post, :through => :user_share_tags_as_sharer, :uniq => true
has_many :recommended_posts, :source => :post, :through => :user_share_tags_as_sharee, :uniq => true

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