Rails透明子关系

class ScheduledEvent < ActiveRecord::Base
    belongs_to :scheduleable, polymorphic:true
    #has column names like #starts_at, #ends_at
end
class AppointmentTypeOne < ActiveRecord::Base
    has_one :scheduled_event, :as=>:scheduleable, :dependent=>:destroy
end
class AppointmentTypeTwo < ActiveRecord::Base
    has_one :scheduled_event, :as=>:scheduleable, :dependent=>:destroy
end

AppointmentTypeOne

AppointmentTypeTwo

#starts_at

#ends_at

#starts_at

#starts_at=

AppointmentX

ScheduledEvent

AppointmentTypeOne.where(\'starts_at IS NOT NULL\')

include