Django 信号 dispatch_uid

Question

我对 dispatch_uid 的用法有疑问为信号。

目前，我通过简单地添加 if not instance.order_reference 来防止信号的多次使用。 .我现在想知道是否dispatch_uid具有相同的功能，我可以删除“if not ”子句。

信号.py

def reserveditem_create_order_reference(sender, instance, **kwargs):
    if not instance.order_reference:
        instance.order_reference = unique_order_reference_generator()

app.py

class OrdersConfig(AppConfig):
    name = 'orders'

    def ready(self):

        #Pre save signal for ReservedItem model
        reserved_model = self.get_model('ReservedItem')
        pre_save.connect(
            reserveditem_create_order_reference,
            sender=reserved_model,
            dispatch_uid="my_unique_identifier"
        )

Answer 1

正如 the docs ,

In some circumstances, the code connecting receivers to signals may run multiple times. This can cause your receiver function to be registered more than once, and thus called multiple times for a single signal event. If this behavior is problematic (such as when using signals to send an email whenever a model is saved), pass a unique identifier as the dispatch_uid argument to identify your receiver function

所以是的，删除 if条款和设置独特的信号接收器 dispatch_uid相反，将阻止您的处理程序被多次连接(以及此后被调用)。