Question

An article has many articles that it refers to and many other articles can refer to it. Sometimes an article can refer to an article that also refers to it.

Answer 1

I’d do it like this:

class Article < ActiveRecord::Base   # mentions in other articles   has_many :references, :foreign_key => 'referred_article_id'   # articles that refer to it   has_many :referrers, :through => :references, :foreign_key => 'referred_article_id'   # articles it refers to   has_many :referred_articles, :through => :references, :foreign_key => 'referrer_id' end  class Reference < ActiveRecord::Base   belongs_to :referrer, :class => Article   belongs_to :referred_article, :class => Article end