Mongoid与“外键”

Question

作为mongodb的资深人士，我创建了以下结构：

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中正确映射这个：

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。我该如何进行参考？

从技术上讲，它是：

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

（意味着用户可以是许多礼物的作者，用户可以是许多礼物的接收者，但礼物只能有1位作者和接收者）。

Plz帮助!!!

Answer 1

如果Gift看起来像这样，你可能会有更好的运气：

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

  name: str 
  ... 
}

然后，在礼物中添加:foreign_key：

class Gift 
  include Mongoid::Document

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