There are different ways you could do this. Here's one option:
class User
include DataMapper::Resource
property :id, Serial
# Other properties...
has 1, :referee, :required => false
has 1, :player, :required => false
end
class Referee
include DataMapper::Resource
# DON'T include "property :id, Serial" here
# Other properties...
belongs_to :user, :key => true
end
class Player
include DataMapper::Resource
# DON'T include "property :id, Serial" here
# Other properties...
belongs_to :user, :key => true
end
Act on the referee/player models like:
u = User.create(...)
u.referee = Referee.create(...)
u.player = Player.create(...)
u.player.kick_ball() # or whatever you want to call
u.player.homeruns
u.referee.flag_play() # or whatever.
See if this works. I haven't actually tested it but it should be good.