整蛊活动记录的关系 - 多态的双向自我指涉 [英] Tricky active record relationships - polymorphic bi-directional self-referential

问题描述

你会如何模拟引用和引文的出版物（文章，书籍，章节，等...）？

How would you model the references and citations to publications (articles, books, chapters, etc...)?

一个出版物可以是一篇文章，书籍或一章，它有许多参考其他出版物和其他出版物引用它（调用这些引文）

A publication can be an article, book or a chapter and it has many references to other publications and other publications refer to it (call these citations)

我需要能够列出出版物之间的关系：从其他出版物在出版物引用和引文本刊物

I need to be able to list the relationships among the publications: The references in a publication and the citations from other publications to this publication

我最初的理解是，这将是一个多态的关系，处理不同类型的出版物，它需要一个bidirectionalself加入。

My initial understanding is that this would be a polymorphic relationship to handle the different types of publications and that it would require a bidirectionalself join.

我吧刺

Publication
belongs_to :writing, :polymorphic =>true
has_and_belongs_to_many :references 
   :class_name => "Publication"
   :join_table => 'reference_citation' 
   :foreign_key => 'reference_id'
   :foreign_key => 'citation_id'

Book,    Chapter,    Article all have:
has_many :publications :as =>writing

我觉得这有点混乱，所以任何建议，这将有助于澄清这将是巨大的。即使对象的字段命名建议。

I find this a bit confusing so any suggestions that would help clarify it would be great. Even object and field naming suggestions.

[我问了一个不太清楚这个版本的问题<一href="http://stackoverflow.com/questions/499934/how-would-you-model-articles-with-references-and-citations-in-rails-activerecord">here.]

[I asked a less clear version of this question here.]

我还可能需要使用有许多通过，因为我需要破坏关系的能力

I also probably need to use has many through because I will need the ability to destroy the relationship

推荐答案

下面是一个使用单表继承使用自引用关系的解决方案。使用这些命令来创建应用程序：

Here's a solution using a self-referential relationship using single table inheritance. Use these commands to create the app:

$ rails myproject
$ cd myproject
$ script/generate model publication type:string name:string
$ script/generate model citation publication_id:integer reference_id:integer

该设置的关系是这样的：

The setup the relationships this way:

class Publication < ActiveRecord::Base
  has_many :citations
  has_many :cited_publications, :through => :citations, :source => :reference
  has_many :references, :foreign_key => "reference_id", :class_name => "Citation"
  has_many :refered_publications, :through => :references, :source => :publication
end

class Citation < ActiveRecord::Base
  belongs_to :publication
  belongs_to :reference, :class_name => "Publication"
end

class Article < Publication
end

class Book < Publication
end

class Chapter < Publication
end

现在，我们可以创建数据库，并尝试从控制台：

Now we can create the DB and try it out from the console:

$ rake db:migrate
$ script/console 
Loading development environment (Rails 2.2.2)
>> a = Article.create!(:name => "Article")
=> #<Article id: 1, ...>
>> b = Book.create!(:name => "Book")
=> #<Book id: 2, ...>
>> a.citations.create(:reference => b)
=> #<Citation id: 1, publication_id: 1, reference_id: 2, created_at: "2009-02-15 14:13:15", updated_at: "2009-02-15 14:13:15">
>> a.citations
=> [#<Citation id: 1, ...>]
>> a.references
=> []
>> b.citations
=> []
>> b.references
=> [#<Citation id: 1, publication_id: 1, reference_id: 2, created_at: "2009-02-15 14:13:15", updated_at: "2009-02-15 14:13:15">]    
>> a.cited_publications
=> [#<Book id: 2, type: "Book", name: "Book", created_at: "2009-02-15 14:11:00", updated_at: "2009-02-15 14:11:00">]
>> a.refered_publications
=> []
>> b.cited_publications
=> []
>> b.refered_publications
=> [#<Article id: 1, type: "Article", name: "Article", created_at: "2009-02-15 14:10:51", updated_at: "2009-02-15 14:10:51">]

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