如何通过第三个模型声明两个模型之间的“直接” has_many关联？

Question

I am using Ruby on Rails 4.1 and I would like to implement a "direct" has_many association between Article and CommentRequest in the following case:

class Article < ActiveRecord::Base
  has_many :comment_associations
  has_many :comments, :through => :comment_associations
end

class Comment < ActiveRecord::Base
  has_many :article_associations
  has_many :articles, :through => :article_associations

  has_many :comment_request_associations
  has_many :comment_requests, :through => :comment_request_associations
end

class CommentRequest < ActiveRecord::Base
  has_many :comment_associations
  has_many :comments, :through => :comment_associations
end

That is, I would like to state a has_many association in both Article and CommentRequest in order to make it possible to run code as-like the following:

@article.comment_requests
@comment_request.articles

If it is possible, how to make that?

Answer 1

You should be able to do

class Article < ActiveRecord::Base
  has_many :comment_associations
  has_many :comments, :through => :comment_associations
  has_many :comment_requests, :through => :comments
end

since rails allows you to nest has_many :through relationships

and similarly

class CommentRequest < ActiveRecord::Base
  has_many :comment_associations
  has_many :comments, :through => :comment_associations
  has_many :articles, :through => :comments
end