如何进行“数量大于零循环”

 def order_success(self, order,
 order_item):
         log.debug(\"Order success called, creating gift certs on order:
 %s\", order)
         message = \"\"
         email = \"\"
         for detl in order_item.orderitemdetail_set.all():
             if detl.name == \"email\":
                 email = detl.value
             elif detl.name == \"message\":
                 message = detl.value

         price=order_item.unit_price
         log.debug(\"Creating gc for %s\", price)
         gc = GiftCertificate(
             order = order,
             start_balance= price,
             purchased_by = order.contact,
             valid=True,
             message=message,
             recipient_email=email
             )
         gc.save()