ActiveRecord having 2 FKs from the same column in a table

问题

Hi I want to allow my users to message each other and I thought of having a table structure like

User: ID | Name

Message: To | From | Body

I'm relatively new to rails and I'm not sure what my model should look like or how to build the relation where I have two FKs from the same column. To & From are the user who sent the message and the receiver. I'm using ActiveRecord for my models.

Can anyone get me pointed in the right direction here? I have a feeling I should be using have_many through but I would like to have the relationship has exactly 2.

回答1:

You can do like this

#user.rb
Class User < ActiveRecord::Base

has_many :messages

end

#message.rb
Class Message < ActiveRecord::Base

belongs_to :sender,class_name => "User",foreign_key => 'from'

belongs_to :receiver,class_name => "User",foreign_key => 'to'

end

Note: It is preferable and also recommended to have integer foreign_keys.If you would like to change the foreign_keys,i would recommend the names sender_id and receiver_id.

来源：https://stackoverflow.com/questions/23714766/activerecord-having-2-fks-from-the-same-column-in-a-table