Rails使用foreign_key和链接表进行建模 [英] Rails model with foreign_key and link table

问题描述

我正在尝试创建一个Ruby on Rails项目的模型，以建立不同单词之间的关系。把它看作是一个字典，其中两个单词之间的链接表明它们可以同义使用。我的数据库看起来像这样：

I am trying to create a model for a ruby on rails project that builds relationships between different words. Think of it as a dictionary where the "Links" between two words shows that they can be used synonymously. My DB looks something like this:

Words
----
id

Links
-----
id
word1_id
word2_id

如何使用链接表创建两个单词之间的关系。我试图创建模型，但不知道如何获得链接表：

How do I create a relationship between two words, using the link-table. I've tried to create the model but was not sure how to get the link-table into play:

class Word < ActiveRecord::Base
  has_many :synonyms, :class_name => 'Word', :foreign_key => 'word1_id'
end

推荐答案

如果您的关联有后缀（如1和2），则设置不正确。试试这个Word模型：

In general, if your association has suffixes such as 1 and 2, it's not set up properly. Try this for the Word model:

class Word < ActiveRecord::Base
  has_many :links, :dependent => :destroy
  has_many :synonyms, :through => :links
end

链接模式：

Link model:

class Link < ActiveRecord::Base
  belongs_to :word
  belongs_to :synonym, :class_name => 'Word'

  # Creates the complementary link automatically - this means all synonymous
  # relationships are represented in @word.synonyms
  def after_save_on_create
    if find_complement.nil?
      Link.new(:word => synonym, :synonym => word).save
    end
  end

  # Deletes the complementary link automatically.
  def after_destroy
    if complement = find_complement
      complement.destroy
    end
  end

  protected

  def find_complement
    Link.find(:first, :conditions => 
      ["word_id = ? and synonym_id = ?", synonym.id, word.id])
  end
end

表：

Tables:

Words
----
id

Links
-----
id
word_id
synonym_id

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