has_many（不同的对象）为：一类对象

Question

我需要一种将 2 个不同对象引用为 1 个对象的方法。

我有一个需要跟踪收件人的消息对象。问题是收件人可能是用户或联系人。

模型应该是：?

class Message < ActiveRecord::Base
  has_many :users, as: :recipients
  has_many :contacts, as: :recipients
end

class User < ActiveRecord::Base
  belongs_to :recipient, polymorphic: true
end

class User < ActiveRecord::Base
  belongs_to :recipient, polymorphic: true
end

因为，我觉得多态关系的建立是为了相反的方向。

此外，这种方式不允许我引用我需要的@message.recipients。

我希望这是有道理的谢谢

Answer 1

你所做的完全不正确。我认为您需要多对多关联。我的联想是：

class Message < ActiveRecord::Base
  has_many :recipient_links
  has_many :users, through: :recipient_links, source: :recipient, source_type: 'User'
  has_many :contacts, through: :recipient_links, source: :recipient, source_type: 'Contact'
end

class Contact < ActiveRecord::Base
  has_many :recipient_links, as: :recipient
  has_many :messages, through: :recipient_links
end

class User < ActiveRecord::Base
  has_many :recipient_links, as: :recipient
  has_many :messages, through: :recipient_links
end

# fields: message_id, recipient_id, recipient_type
class RecipientLink < ActiveRecord::Base
  belongs_to :recipient, polymorphic: true
  belongs_to :message
end

Answer 2

...我还不能添加评论所以我在这里给出解决方案：当使用 up 的答案接收所有 @message.recipients 每种类型时只有 2 个请求：

RecipientLink.includes(:recipient).where(message_id: @message.id).collect(&:recipient)

has_many（不同的对象）为：一类对象

has_many (different objects) as: one type of object

ruby-on-rails

polymorphic-associations