has_one 有两个外键？

我有两个类“消息”和“用户”。消息具有 sender_id 和recipient_id 这两个用户的外键。如何建立关系，使我能够获取发件人和收件人的用户，例如 @message.sender.name 和 @message.recipient.name

我尝试通过这种方式做到这一点：

class Message < ActiveRecord::Base  

  belongs_to :sender, :class_name => 'User', :foreign_key => 'sender'
  belongs_to :recipient, :class_name => 'User', :foreign_key => 'recipient'

end   

class User < ActiveRecord::Base

  has_many :recivied_messages, :class_name => 'Message', :foreign_key => 'recipient'
  has_many :send_messages, :class_name => 'Message', :foreign_key => 'sender'
end

但这并没有帮助，例如，当我尝试访问 @message.recipient.name 时，它​​说“未定义的方法‘名称’”

您可以使用:class_name属性来设置哪个类用作外键：

class Message < ActiveRecord::Base
  has_one :sender, :class_name => User
  has_one :recipient, :class_name => User
end

class User < ActiveRecord::Base
  belongs_to :sent_messages, :class_name => Message
  belongs_to :received_messages, :class_name => Message
end

另外，你说你正在使用sender_id and recipient_id对于外键，但在您的代码中您有:foreign_key => 'sender' and :foreign_key => 'recipient'。您是否尝试过将它们更改为:foreign_key => 'sender_id' and :foreign_key => 'recipient_id'? So:

class Message < ActiveRecord::Base
  has_one :sender, :class_name => User, :foreign_key => 'sender_id'
  has_one :recipient, :class_name => User, :foreign_key => 'recipient_id'
end

class User < ActiveRecord::Base
  belongs_to :sent_messages, :class_name => Message, # ...etc
  belongs_to :received_messages, :class_name => Message, # ...etc
end