Question

以下是我的模特的摘录：

class Order(models.Model):
    ...
    content_type = models.ForeignKey(ContentType)
    user = models.ForeignKey('auth.User')


class OrderItem(models.Model):
    ...
    unit_price = models.DecimalField(max_digits=7, decimal_places=2, blank=True)
    quantity = models.SmallIntegerField()
    order = models.ForeignKey(Order)

我有一个仪表板，我想显示已售商品的总数。我正在努力将unit_price乘以quantity。

Answer 1

您可以使用extra()查询执行此操作：

OrderItem.objects.extra(select={'total': 'unit_price * quantity'})

您可以将属性total添加到OrderItem：

class OrderItem(models.Model):
    ...
    unit_price = models.DecimalField(max_digits=7, decimal_places=2, blank=True)
    quantity = models.SmallIntegerField()

    @property
    def total(self):
        return unit_price * quantity

# you can then access it like any other field (but you cannot filter on it)
print OrderItem.objects.get(pk=1).total

获得单价*总数

1 个答案: