为什么我在执行大额求和时在 DJango 中收到“无法解析关键字”错误？

Question

我正在开发一个电子商务网站，只有登录用户才能下订单。我想在结帐时获取所有订单的总价（即

order_price_total

），但出现错误：

Cannot resolve keyword 'order_price_total' into field. Choices are: delivered, id, order_date, paid, product, product_id, quantity, ready_for_delivery, shipped, user, user_id

下面是我的代码摘录（模型和视图）：

class Product(models.Model):
    supplier = models.ForeignKey(Shop, on_delete=models.CASCADE)
    product_name = models.CharField(max_length=100, null=True, blank=True)
    brand_name = models.CharField(max_length=100, null=True, blank=True)
    image = models.FileField(upload_to='meadia/product-image', null=True)
    key_features = models.TextField(max_length=1000, null=True, blank=True)
    specifications = models.TextField(max_length=1000, null=True, blank=True)
    description = models.TextField(max_length=1000, null=True, blank=True)
    creation_date = models.DateTimeField(auto_now_add=True)
    
    def __str__(self):
        return self.product_name


class Order(models.Model):
    user = models.ForeignKey(CustomUser, on_delete=models.DO_NOTHING)
    product = models.ForeignKey(Product, on_delete=models.DO_NOTHING)
    quantity = models.IntegerField(default=1, null=True, blank=True)
    order_date = models.DateTimeField(auto_now_add=True)
    
    paid = models.BooleanField(default=False)
    shipped = models.BooleanField(default=False)
    ready_for_delivery = models.BooleanField(default=False)
    delivered = models.BooleanField(default=False)

    def order_price_total(self):
        if self.paid == False:
            total_price = self.product.current_price * self.quantity
        return (total_price)
        
    def __str__(self):
        return self.product.product_name



##VIEW
@login_required(login_url='login')
def orders(request):
    order = Order.objects.filter(user=request.user)
    total_amount = Order.objects.filter(user=request.user, paid=False, delivered=False).aggregate(TOTAL = Sum('order_price_total'))['TOTAL'] or 0

    context={
            'order':order,
            'total_amount':total_amount,
        }
    return render(request, 'mainapp/cart.html', context)

Answer 1

使用属性标签
如下

class Order(models.Model):
        user = models.ForeignKey(CustomUser, on_delete=models.DO_NOTHING)
        product = models.ForeignKey(Product, on_delete=models.DO_NOTHING)
        quantity = models.IntegerField(default=1, null=True, blank=True)
        order_date = models.DateTimeField(auto_now_add=True)
    
    paid = models.BooleanField(default=False)
    shipped = models.BooleanField(default=False)
    ready_for_delivery = models.BooleanField(default=False)
    delivered = models.BooleanField(default=False)


    @property
    def order_price_total(self):
        if self.paid == False:
            total_price = self.product.current_price * self.quantity
        return (total_price)
        
    def __str__(self):
        return self.product.product_name

在模板中您可以使用 order.order_price_total