python - 如何排除Django中的数据

Question

我试图排除在我的 orderRequest 表中的订单，但它只显示在 orderRequest 表中的订单并排除其他订单。Function 获得正确的订单 ID，但不排除该订单。它排除其他订单并显示已经在 orderRequest 表中的订单
查看.py

class OrderProduct_View(TemplateView):

     template_name = 'purchase/orderProduct.html'

     def get(self, request, *args, **kwargs):
         allOrder = OrderProduct.objects.all()
         allOrd = Order.objects.all()
         categories = Category.objects.all()
         categoryId = self.request.GET.get('SelectCategory')
         product = Product.objects.filter(category_id=categoryId)

     def filter_order(order):
         try:
            orderReq = order.orderRequest
            return orderReq
         except:
            return True

     filteredOrders = list(filter(filter_order, allOrd))
   
     args = {'categories': categories, 'product': product, 'filteredOrders': filteredOrders}

     return render(request, self.template_name, args)

模型.py

class OrderProduct(models.Model):
     product = models.ForeignKey(Product, on_delete=models.CASCADE)
     description = models.CharField(max_length=90)
     quantity = models.IntegerField()
     order_cancel = models.BooleanField(default=False)

class Order(models.Model):
     orderProduct = models.ForeignKey(OrderProduct, on_delete=models.CASCADE)
     created_by = models.CharField(max_length=20)
     created_at = models.DateTimeField(auto_now_add=True)
     destination = models.CharField(max_length=30)
     vendor = models.ForeignKey(Vendor, on_delete=models.CASCADE)
     shipping_cost = models.IntegerField()


class OrderRequest(models.Model):
     order_status = models.CharField(max_length=10)
     order = models.OneToOneField(Order, related_name='orderRequest', on_delete=models.CASCADE)

HTML

  {% for allOrders in filteredOrders%}
       {{ allOrders.orderProduct.id }} 
       {{ allOrders.orderProduct.product.name }}
       {{ allOrders.orderProduct.quantity }}
       <button><a href="{% url 'allVendor' %}?product_id={{ allOrders.orderProduct.product.id }}&orderProducts_id={{ allOrders.orderProduct.id }}">Place Order</a></button>
  {% endfor %}

Answer 1

您可以使用 isnull lookup [Django docs]查找没有相关实例的实例，因此要查找 Order没有 OrderRequest 的实例您可以使用的实例:

Order.objects.filter(orderRequest__isnull=True)

因此，您可以将 View 写为:

class OrderProduct_View(TemplateView):
    template_name = 'purchase/orderProduct.html'
    
    def get(self, request, *args, **kwargs):
        filteredOrders = Order.objects.filter(orderRequest__isnull=True)
        categories = Category.objects.all()
        categoryId = self.request.GET.get('SelectCategory')
        product = Product.objects.filter(category_id=categoryId)
        args = {'categories': categories, 'product': product, 'filteredOrders': filteredOrders}
        return render(request, self.template_name, args)

Note: Class names should be in PascalCase so OrderProductView instead of OrderProduct_View. Variable names should be insnake_case so filtered_orders instead of filteredOrders,etc. See PEP 8 -- Style Guide for PythonCode