如何从Django模型中删除记录

我有一个Django模型，如下所示：

class Calculations(models.Model):
    category = models.CharField(max_length=127)
    make = models.CharField(max_length=127)
    model = models.CharField(max_length=127)
    customer = models.ForeignKey(to=Customer, null=True, blank=True)
    data = models.TextField(null=True, blank=True)

class Customer(models.Model):
    title = models.CharField(max_length=4, null=True)
    firstname = models.CharField(max_length=30)
    lastname = models.CharField(max_length=30)
    email = models.EmailField(null=True)
    address = models.CharField(max_length=80)

Customer.objects.filter(id=some_id).delete()

客户模型如下：

class Calculations(models.Model):
    category = models.CharField(max_length=127)
    make = models.CharField(max_length=127)
    model = models.CharField(max_length=127)
    customer = models.ForeignKey(to=Customer, null=True, blank=True)
    data = models.TextField(null=True, blank=True)

class Customer(models.Model):
    title = models.CharField(max_length=4, null=True)
    firstname = models.CharField(max_length=30)
    lastname = models.CharField(max_length=30)
    email = models.EmailField(null=True)
    address = models.CharField(max_length=80)

Customer.objects.filter(id=some_id).delete()

我想从客户中删除一条记录。我的做法如下：

class Calculations(models.Model):
    category = models.CharField(max_length=127)
    make = models.CharField(max_length=127)
    model = models.CharField(max_length=127)
    customer = models.ForeignKey(to=Customer, null=True, blank=True)
    data = models.TextField(null=True, blank=True)

class Customer(models.Model):
    title = models.CharField(max_length=4, null=True)
    firstname = models.CharField(max_length=30)
    lastname = models.CharField(max_length=30)
    email = models.EmailField(null=True)
    address = models.CharField(max_length=80)

Customer.objects.filter(id=some_id).delete()

但这会删除

客户

和

计算

我可能应该在_delete上使用

，例如：

customer = models.ForeignKey(to=Customer, null=True, blank=True, on_delete=models....)

但是，我想要的是：


如果我删除
计算
，那么我还想删除客户
但是，如果我从
customer
中删除一条记录，我只希望删除该客户，并删除计算中的
customer\u id
，因此不会删除整个计算记录

你知道怎么做吗
 要在删除
计算时删除
客户
：

def delete(self, *args, **kwargs):
    self.customer.delete()
    super(Calculations, self).delete(*args, **kwargs)

要避免在删除
客户时删除
计算
：

customer = models.ForeignKey(to=Customer, null=True, blank=True, on_delete=models.SET_NULL)