Django pre_save 触发两次
我正在使用 django 信号进行数据非规范化。这是我的代码：
# vote was saved
@receiver(pre_save, sender=Vote)
def update_post_votes_on_save(sender, instance, **kwargs):
""" Update post rating """
# is vote is being updated, then we must remove previous value first
if instance.id:
old_vote = Vote.objects.get(pk=instance.id)
instance.post.rating -= old_vote.value
# now adding the new vote
instance.post.rating += instance.value
instance.post.save()
我不明白为什么，但是当保存我的 Vote 实例时，update_post_votes_on_save() 被调用两次。我认为我的代码中有一个错误，但通过管理界面保存给出了相同的结果。
文档说了一些关于 使用 dispatch_uid防止重复调用，但我无法理解是否是这种情况。如何使用dispatch_uid？我已经尝试过这个，但没有运气：
@receiver(pre_save, sender=Vote, dispatch_uid="my_unique_identifier")
任何想法为什么函数被调用两次以及如何避免它？
I am using django signals for data denormalization. Here is my code:
# vote was saved
@receiver(pre_save, sender=Vote)
def update_post_votes_on_save(sender, instance, **kwargs):
""" Update post rating """
# is vote is being updated, then we must remove previous value first
if instance.id:
old_vote = Vote.objects.get(pk=instance.id)
instance.post.rating -= old_vote.value
# now adding the new vote
instance.post.rating += instance.value
instance.post.save()
I cannot understand why, but when my Vote instance is being saved, update_post_votes_on_save() is being called twice. I thought there was a bug in my code, but saving through admin interface gives the same result.
Docs say something about using dispatch_uid to prevent duplicate calls, but I cannot understand if this is the case. How to use dispatch_uid? I've tried this, but with no luck:
@receiver(pre_save, sender=Vote, dispatch_uid="my_unique_identifier")
Any ideas why function is being called twice and how to avoid it?
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很抱歉，造成了混乱，但毕竟
dispatch_uid解决了问题。请记住，在提出有关 SO 的问题之前，您可能必须重新启动开发服务器才能看到效果:)I'm sorry, for the confusement, but
dispatch_uidsolved the problem, after all. Just remember, that you might have to restart the development server to see the effect, before asking a question on SO :)