Has_many，通过关联 [英] Has_many, through association

问题描述

警告:Total Rails Newb (TRN).这应该是一个非常基本的问题，所以我希望有人能抽出几分钟来帮助阐明.

Warning:Total Rails Newb (TRN). This should be a pretty basic question so I'm hoping someone can spare a couple mins to help shed some light.

假设我有以下模型:用户、组和成员一个用户可以有很多组(比如朋友、家人等)一个群组可以有多个成员，即其他用户.

Let's say I have the following models: User, Group, and Member A user can have many groups (let's say friends, family, etc) A group can have many members, namely other users.

我将如何构建它?

最初我试过这个:

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

class Groups < ActiveRecord::Base
  has_many :users, :through => :members
  belongs_to :user
end

class Member < ActiveRecord::Base
  belongs_to :group
  belongs_to :user
end

但是这给了我一个用户错误，所以我改变了

However this gave me an error in User so I changed

has_many :groups, :through => :members

到

has_many :memberships, :through => :members, :source => :groups

当我尝试执行时仍然收到关于缺少关联的错误

Still getting an error about missing association when I try to do

group = Group.new
group.user.new

推荐答案

它会很有用:http://railscasts.com/episodes/47-two-many-to-many

class User < ActiveRecord::Base
  has_many :members
  has_many :groups, :through => :members
  has_many :groups_as_owner, :class_name => "Group"
end

class Groups < ActiveRecord::Base
  has_many :members
  has_many :users, :through => :members
  belongs_to :owner, :class_name => "User", :foreign_key => :user_id
end

class Member < ActiveRecord::Base
  belongs_to :group
  belongs_to :user
end

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