Mongoid與「外鍵」

Question

由於MongoDB中的老手，我創建了以下結構：

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

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

    name: str 
    ... 
} 

而且我想在mongoid正確映射這樣的：

class User 
    include Mongoid::Document 

    has_many :gifts 
end 

class Gift 
    include Mongoid::Document 

    belongs_to :user 
end 

然而，映射不正確。 g = Gift.first; g.author沒有定義。我如何做參考？

從技術上講，它是：

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

（這就意味着用戶可以是許多禮物的作者，並且用戶可以是許多禮物接收者，而是一個禮物只能有1個作家和接收器）。

Plz help !!!

Answer 1

你可能要使用Rails更好的運氣，如果禮物是這樣的：

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

    name: str 
    ... 
} 

，然後添加一個:foreign_key禮物：

class Gift 
    include Mongoid::Document 

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