Django 如何在pre_save功能中获取旧值和新值-解网

问：

想象一下，我有一个名为的模型，它有一个名为的字段。如何在信号中获取以前的值和新值？Anamepre_save

@receiver(pre_save, sender=A)
def signal_product_manage_latest_version_id(
        sender, instance, update_fields=None, **kwargs):
    if 'name' in update_fields:
        print(instance.name)

当我调用以下内容时，是旧值还是新值？name

a = A.objects.create(name="John")
a.name = "Lee"
a.save()

django django-orm django-signals

@receiver(pre_save, sender=A)
def signal_product_manage_latest_version_id(sender, instance, update_fields=None, **kwargs):
    try:
        old_instance = A.objects.get(id=instance.id)
    except A.DoesNotExist:  # to handle initial object creation
        return None  # just exiting from signal
    # your code to with 'old_instance'

Django 如何在pre_save功能中获取旧值和新值

django how to get old value and new value in pre_save fucntion

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