ruby on rails - Foreign Keys pointing to same Model -

i have user model

class user < activerecord::base   attr_accessible :email, :name    has_many :client_workouts end 

and clientworkout model

class clientworkout < activerecord::base   attr_accessible :client_id, :trainer_id, :workout_id    belongs_to :client, :class_name => user, :foreign_key => 'client_id'    belongs_to :trainer, :class_name => user, :foreign_key => 'trainer_id'   end 

i first want know or if i'm doing wrong when writing associations. ideally want able call query find user's clients workouts user's id matches client_id or trainer_id. so...

user.client_workouts.trainer??? 

this not work rails assumes clientworkout have user_id column. don't think there way make has_many relation matches 2 columns... instead create method this:

class user < activerecord::base   attr_accessible :email, :name    has_many :client_workouts, :foreign_key => "client_id"    has_many :trainer_workouts, :foreign_key => "trainer_id"    def client_and_trainer_workouts     clientworkouts.where("client_id = ? or trainer_id = ?", id, id)   end end 

otherwise create scope on clientworkout model this:

class clientworkout < activerecord::base   attr_accessible :client_id, :trainer_id, :workout_id    belongs_to :client, :class_name => user, :foreign_key => 'client_id'    belongs_to :trainer, :class_name => user, :foreign_key => 'trainer_id'      scope :workouts_for_user,        lambda {|user| where("client_id = ? or trainer_id = ?", user.id, user.id) } end 

you both, , let method on use call scope on clientworkout.