如果你真的想使用信号来实现这一目标，这里简单介绍一下，
from django.db.models.signals import post_savefrom django.dispatch import receiverclass TransactionDetail(models.Model): product = models.ForeignKey(Product)# method for updating@receiver(post_save, sender=TransactionDetail, dispatch_uid="update_stock_count")def update_stock(sender, instance, **kwargs): instance.product.stock -= instance.amount instance.product.save()
