has_many :through question

This isn't has_many :through, it's just a simple has_many association.

class User
  has_many :sent_messages, :class_name => 'Message', :foreign_key => 'sender_id'
  has_many :received_messages, :class_name => 'Message', :foreign_key
=> 'receiver_id'
end

class Message
  belongs_to :sender, :class_name => 'User'
  belongs_to :receiver, :class_name => 'User'
end