@api.multi
@api.constrains('event_ticket_id', 'state')
def _check_ticket_seats_limit(self):
    for record in self:
        if (record.event_ticket_id.seats_max and (record.event_ticket_id.seats_available < 0)):
            raise ValidationError(_('No more available seats for this ticket'))
@api.multi
@api.constrains('event_ticket_id', 'state')
def _check_ticket_seats_limit(self):
    for record in self:
        if (record.event_ticket_id.seats_max and (record.event_ticket_id.seats_available < 0)):
            raise ValidationError(_('No more available seats for this ticket'))