如何将一个模型两次关联到另一个模型

Question

嗨我正在制作一个小网站,以帮助我和朋友学习语言.典型用途:

亚当是英国人,但正在学习日语.亚当可以通过撰写和提交用日语写的文章来练习他的日语.Adam(不允许)提交用他的母语撰写的任何文章.亚当可以阅读正在学习英语的其他用户的文章(用英语写的)

我试图思考如何模拟这个并且证明比标准轨道更困难,许多属于我习以为常的协会.

我需要像这样的功能

-show all articles written in adams native language
@adam.native_language.articles

-show all posts written by users just like adam (i.e. learning the same language)
@adam.foreign_language.articles

-perhaps showing all posts written by language learners in one particular language
@language => Japanese
@langauge.posts

我需要一个用户,文章和语言模型.但是,我如何关联语言和用户模型？感觉语言应该与用户模型相关联两次,一次用于native_language,一次用于foreign_language.

Answer 1

是啊,你说得对.用户和语言之间的关联是双重的.使用Rails模拟这种情况非常容易:

class Language < AR::Base
  has_many :native_speakers, :class_name => "User", :foreign_key => "native_language_id"
  has_many :second_language_speakers, :class_name => "User", :foreign_key => "second_language_id"
  has_many :articles
end

class User < AR::Base
  # we expect the users table to have native_language_id and second_language_id columns
  belongs_to :native_language, :class_name => "Language"
  belongs_to :second_language, :class_name => "Language"
  has_many :second_language_articles, :through => :second_language, :source => :articles
  has_many :native_language_articles, :through => :native_language, :source => :articles
end

class Article < AR::Base
  belongs_to :language
end

这样的事情应该有效.