Question

晚上好。目的是在创建 Transfer 模型时，将 sum 字段从 whom_from 中减去并添加到 whom_to Bill的模型。据我了解，这需要通过save（）完成，但是显然我没有正确设置它。可能是什么问题？

models.py

class Bill(models.Model):
    title = models.CharField(max_length=100)
    amount = models.DecimalField(max_digits=19, decimal_places=2, 
                                 validators=[MinValueValidator(0)], default=0)

    def __str__(self):
        return self.title


class Transfer(models.Model):
    whom_from = models.ForeignKey(Bill, on_delete=models.CASCADE, related_name='whom_from')
    whom_to = models.ForeignKey(Bill, on_delete=models.CASCADE, related_name='whom_to')
    sum = models.DecimalField(max_digits=19, decimal_places=2, validators=[MinValueValidator(0)], default=0)

    def save(self, *args, **kwargs):
        self.whom_to.amount = self.whom_to.amount + self.sum
        self.whom_from.amount = self.whom_from.amount - self.sum
        super(Transfer, self).save(*args, **kwargs)

如何从另一个表字段更改数据？

0 个答案: