Python .delete（）不处理从signals.py Django调用的记录

我正在创建一个计费面板。在将重复的帐单地址分配给订单实例的部分中，它会自动删除，并将以前的帐单地址分配给订单。虽然前一个账单实例被分配给订单，但重复的账单地址实例不会被删除。我是个笨蛋。模型中没有重写的delete方法

models.py：-

class BillingAddress(models.Model):
      #Contains address and email and other info

class Order(models.Model):
      billingAddress = billingAddress = models.ForeignKey(BillingAddress, 
                                     null=True,on_delete=models.SET_NULL
                                    )

signals.py：-

@receiver(post_save, sender=Order)
def dont_save_if_all_fields_matching(sender, instance, created, **kwargs):
    if created:
        currentOrder = instance
        previousBilling = BillingAddress.objects.filter(user=currentOrder.user,
                                                        firstname=currentOrder.billingAddress.firstname,
                                                        lastname=currentOrder.billingAddress.lastname,
                                                        phonenumber=currentOrder.billingAddress.phonenumber,
                                                        address1=currentOrder.billingAddress.address1,
                                                        address2=currentOrder.billingAddress.address2,
                                                        city=currentOrder.billingAddress.city,
                                                        country=currentOrder.billingAddress.country,
                                                        state=currentOrder.billingAddress.state,
                                                        pincode=currentOrder.billingAddress.pincode
                                                        )
        if len(previousBilling) > 0:
            currentBillingId = currentOrder.billingAddress.id
            currentOrder.billingAddress = previousBilling[0]
            currentOrder.save()
            BillingAddress.objects.get(id=currentBillingId).delete()
            #The above code is not working

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previousBilling=BillingAddress.objects.get（id=currentBillingId） previousBilling.delete（）