HABTM多态关系 [英] HABTM Polymorphic Relationship

问题描述

我是pretty的新的Rails，我试图做一个多态HABTM关系。问题是，我有三个车型，我想有关。

第一个是事件模型，然后是2种与会者：用户和联系人

我想要做的是能够涉及的与会者用户和联系人。那么，是什么我现在在我的code是：

事件模型

  has_​​and_belongs_to_many：参加者，多态=＆GT;真正
 

用户模型

  has_​​and_belongs_to_many：事件：为=＆GT; ：参加者
 

联系型号

  has_​​and_belongs_to_may：事件：为=＆GT; ：参加者
 

1. 如何HABTM表迁移需要呢？我有点困惑，我发现在没有任何帮助。
2. 难道是去上班？

解决方案

没有，你不能这样做，有没有这样的东西作为一个多态has_and_belongs_to_many关联。

你可以做的是建立一个中间模式。或许，这将是这样的：

 类认购＆LT;的ActiveRecord :: Base的
  belongs_to的：与会者，多态=＆GT;真正
  belongs_to的：事件
结束

类事件＆LT;的ActiveRecord :: Base的
  的has_many：订阅
结束

类用户的LT;的ActiveRecord :: Base的
  的has_many：订阅：如=＆GT; ：与会者
  的has_many：事件：通过=＆GT; ：订阅
结束

一流的联系与LT;的ActiveRecord :: Base的
  的has_many：订阅：如=＆GT; ：与会者
  的has_many：事件：通过=＆GT; ：订阅
结束
 

这种方式认购模型表现像A N链接表：N的关系，但可以让你拥有多态行为的事件

。

I'm pretty new to Rails, and i'm trying to do a polymorphic HABTM relationship. The problem is that I have three models that I want to relate.

The first one is the Event model and then are two kind of attendees: Users and Contacts.

What I want to do is to be able to relate as an attendee both users and contacts. So, what i have right now in my code is:

Event Model

has_and_belongs_to_many :attendees, :polymorphic => true

User Model

has_and_belongs_to_many :events, :as => :attendees

Contact Model

has_and_belongs_to_may :events, :as => :attendees

1. How the HABTM table migration needs to be? I'm a little confused and i have found no help on that.
2. Is it going to work?

解决方案

No, you can't do that, there's no such thing as a polymorphic has_and_belongs_to_many association.

What you can do is create a middle model. It would probably be something like this:

class Subscription < ActiveRecord::Base
  belongs_to :attendee, :polymorphic => true
  belongs_to :event
end

class Event < ActiveRecord::Base
  has_many :subscriptions
end

class User < ActiveRecord::Base
  has_many :subscriptions, :as => :attendee
  has_many :events, :through => :subscriptions
end

class Contact < ActiveRecord::Base
  has_many :subscriptions, :as => :attendee
  has_many :events, :through => :subscriptions
end

This way the Subscription model behaves like the link table in a N:N relationship but allows you to have the polymorphic behavior to the Event.

这篇关于HABTM多态关系的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！