三人在Ruby中加入on Rails的 [英] Triple join in Ruby on Rails

问题描述

我有一个关于Ruby on Rails中的关联问题。在应用有项目，用户，角色和组。该项目属于与用户的组，用户可以属于多个不同的组，但只能有该组中的一个具体的作用。例如：

I have question regarding associations in Ruby on Rails. In the application there are projects, users, roles and groups. The project belongs to a group with users, a user can belong to many different groups but can only have one specific role within that group. For example:

在一组用户是项目业主，但在另外一组，他是一个作家。

In one group the user is the project owner, but in another group he is a writer.

什么是实现这个使用内置的功能在Rails中的最佳方式是什么？

What is the best way to implement this using the built in functions in Rails?

感谢

推荐答案

下面是一个非常快的一套模式，可以满足您的需要：

Here is a very quick set of models that should fulfill your requirements:

class User < ActiveRecord::Base
  has_many :group_memberships
  has_many :groups, :through => :group_memberships
end

class GroupMembership < ActiveRecord::Base
  belongs_to :user
  belongs_to :role
  belongs_to :group
end

class Role < ActiveRecord::Base
  has_many :group_memberships
end

class Group < ActiveRecord::Base
  has_many :group_memberships
  has_many :users, :through > :group_memberships
end

基本上没有，有一个用户，组和角色ID在它连接表。我会离开的迁移作为练习提问

Basically there is a join table that has a user, group and role id in it. I'll leave the migrations as an exercise for the questioner

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