带“外键”的Mongoid

Question

作为mongodb的老手，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中正确地映射这一点：

class User 
  include Mongoid::Document

  has_many :gifts
end

class Gift 
  include Mongoid::Document

  belongs_to :user
end

但是，映射是不正确的。G= Gift.first；未定义g.author。如何进行引用？

从技术上讲，它是：

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

(这意味着一个用户可以是许多礼物的作者，一个用户可以是许多礼物的接收者，但一个礼物只能有一个作者和接收者)。

请帮帮我！

Answer 1

如果Gift看起来像这样，你可能会更幸运地使用Rails：

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

  name: str 
  ... 
}

然后，向Gift添加一个:foreign_key：

class Gift 
  include Mongoid::Document

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