Rails 4 : Access attributes from model -

i have model reservation 2 columns, user_id , teleporter_id.

i want lock creation of reservation 3 same teleporter_id don't know how access attribute teleporter_id model i'm creation.

here code :

class reservation < activerecord::base   # relations   belongs_to :teleporter   belongs_to :user    # validations   validate :max_reservation    def max_reservation     if reservation.where(:teleporter_id => self.teleporter_id).count >= 3       errors.add(:base, t('reservation.model.error.max_reservation'))     end   end end 

i think problem self.teleporter_id don't know how access attribut teleporter_id current model.

try this:

def max_reservation   _id = self.teleporter_id   errors.add(:base, t('reservation.model.error.max_reservation')) unless reservation.where(teleporter_id: _id).count <= 3 end