Message Example

message.rb

class Message < ActiveRecord::Base
  belongs_to :recipient, :class => 'User'
  belongs_to :sender, :class => 'User'
end

user.rb

class User < ActiveRecord::Base
  has_many :messages, :foreign_key => :recipient_id, :dependent => :destroy
  has_many :sent_messages, :foreign_key => :sender_id, :class => 'Message', :dependent => :destroy
end