Mongoid 关系多态关联

Question

有谁知道如何在Mongoid中做多态关联这是关系的好处，但不是嵌入的。

例如，这是我的 Assignment模型:

class Assignment
  include Mongoid::Document
  include Mongoid::Timestamps

  field :user
  field :due_at, :type => Time

  referenced_in :assignable, :inverse_of => :assignment
end

可以与多个模型具有多态关系:

class Project
  include Mongoid::Document
  include Mongoid::Timestamps

  field :name, :type => String

  references_many :assignments
end

这会引发错误，指出未知常量可分配。当我更改 reference至 embed ，这一切都如 Mongoid's documentation 中所述，但我需要它是 reference .

谢谢!

Answer 1

回答一个古老的帖子，但有人可能会发现它很有用。

现在还有一个多态 belongs_to :

class Action                                                                                                                           
  include Mongoid::Document                                                                                                            
  include Mongoid::Timestamps::Created                                                                                                 

  field :action, type: Symbol

  belongs_to :subject, :polymorphic => true                                                                                            
end

class User                                                                                                                             
  include Mongoid::Document                                                                                                            
  include Mongoid::Timestamps                                                                                                          
  field :username, type: String
  has_many :actions, :as => :subject   
end

class Company                                                                                                                          
  include Mongoid::Document                                                                                                            
  include Mongoid::Timestamps                                                                                                          

  field :name, type: String                                                                                                            

  has_many :actions, :as => :subject
end