box-o-sand/rails/map-mash/app/models/mash.rb

class Mash < ActiveRecord::Base
  belongs_to :map_a, :class_name => 'Map'
  belongs_to :map_b, :class_name => 'Map'
  belongs_to :winner, :class_name => 'Map'
  has_one :tournament, :class_name => 'MashTournament'
  has_one :round, :class_name => 'MashTournamentRound'

  named_scope :unplayed, :conditions => [%{
        winner_id IS NULL
        AND map_a_id IS NOT NULL
        AND map_b_id IS NOT NULL
    }]
end