ruby-on-rails - 带有 "Foreign Key"的 Mongoid

Question

作为mongodb的老手，我创建了如下结构:

User: { 
  name: str, 
  email: ... 
}

Gift: { 
  # author and receiver refer to User objects obviously
  author: object_id(...),     
  receiver: object_id(...), 

  name: str 
  ... 
}

我想在 mongoid 中正确映射它:

class User 
  include Mongoid::Document

  has_many :gifts
end

class Gift 
  include Mongoid::Document

  belongs_to :user
end

但是，映射不正确。 g = Gift.first; g.author 未定义。我如何做引用？

从技术上讲，它是:

User <--- 1: N via author---> Gift <--- N:1 via receiver---> User

(意思是一个用户可以是很多礼物的作者，一个用户可以是很多礼物的接收者，但是一个礼物只能有一个作者和接收者)。

请帮忙!!!

Answer 1

如果 Gift 看起来像这样，你可能会更喜欢 Rails:

Gift: { 
  # author and receiver refer to User objects obviously
  author_id: object_id(...),     
  receiver_id: object_id(...), 

  name: str 
  ... 
}

然后，在 Gift 中添加一个 :foreign_key:

class Gift 
  include Mongoid::Document

  belongs_to :user, :foreign_key => 'author_id'
end