Django，Python：无法过滤具有传递值的产品真正获取请求并订购产品

Question

我正在尝试过滤一些产品，并按价格升序和降序对过滤后的产品进行排序。

这是我在视图中的代码：

def is_valid_queryparam(param):
    return param != '' and param is not None

def filter(request):
  if request.GET:
      price_min = request.GET.get('priceMin')
      price_max = request.GET.get('priceMax')
      sort_by = request.GET.get("sort", "l2h")

      if is_valid_queryparam(price_min):
          if sort_by == "l2h":
              products = Product.objects.filter(price__gte=price_min).order_by('price')
          elif sort_by == "h2l":
              products = Product.objects.filter(price__gte=price_min).order_by('-price')
          paginator = Paginator(products, 9)
          page = request.GET.get('page')
          paged_products = paginator.get_page(page)
          product_count = products.count()

      if is_valid_queryparam(price_max):
          if sort_by == "l2h":
              products = Product.objects.filter(price__lte=price_max).order_by('price')
          elif sort_by == "h2l":
              products = Product.objects.filter(price__lte=price_max).order_by('-price')
          paginator = Paginator(products, 9)
          page = request.GET.get('page')
          paged_products = paginator.get_page(page)
          product_count = products.count()
  else:   
      products = Product.objects.all().order_by('price')
      paginator = Paginator(products, 9)
      page = request.GET.get('page')
      paged_products = paginator.get_page(page)
      product_count = products.count()

  context={
      'products': paged_products,
      'product_count': product_count,
  }
  return render(request, 'store.html', context)

如果我尝试根据最低和最高价格进行过滤，它会起作用，但是当我尝试排序或没有应用过滤器时，我会得到这个 UnboundLocalError：

UnboundLocalError at /store/
local variable 'paged_products' referenced before assignment
Request Method: GET
Request URL:    http://127.0.0.1:8000/store/?sort=h2l
Django Version: 3.1
Exception Type: UnboundLocalError
Exception Value:    
local variable 'paged_products' referenced before assignment
Exception Location: C:\Users\store\views.py, line 299, in filter

我研究了 Django 文档、google 和 SO，但没有找到解决方案。 我试图重新排列代码，将变量声明为全局变量，从request.GET 参数中排除“排序”，但没有成功。

Answer 1

您收到UnboundLocalError 错误，因为您没有为if is_valid_queryparam(price_min): 和if is_valid_queryparam(price_max): 以及排序依据定义else 块。因此，当您不应用过滤器时，paged_products 和 product_count 永远不会被定义并引发 UnboundLocalError at /store/ local variable 'paged_products' referenced before assignment。

试试下面的代码，这将消除问题并优化代码。

def is_valid_queryparam(param):
    return param != '' and param is not None

def filter(request):
    if request.GET:
        price_min = request.GET.get('priceMin')
        price_max = request.GET.get('priceMax')
        sort_by = request.GET.get("sort", "l2h")

        if is_valid_queryparam(price_min):
            if sort_by == "l2h":
                products = Product.objects.filter(price__gte=price_min).order_by('price')
            elif sort_by == "h2l":
                products = Product.objects.filter(price__gte=price_min).order_by('-price')
            else:
                products = Product.objects.filter(price__gte=price_min)
        else:
            products = Product.objects.all().order_by('price')

        if is_valid_queryparam(price_max):
            if sort_by == "l2h":
                products = Product.objects.filter(price__lte=price_max).order_by('price')
            elif sort_by == "h2l":
                products = Product.objects.filter(price__lte=price_max).order_by('-price')
            else:
                products = Product.objects.filter(price__lte=price_max)
        else:
            products = Product.objects.all().order_by('price')
    else:
        products = Product.objects.all().order_by('price')

    paginator = Paginator(products, 9)
    page = request.GET.get('page')
    paged_products = paginator.get_page(page)
    product_count = products.count()

    context = {
        'products': paged_products,
        'product_count': product_count,
    }
    return render(request, 'store.html', context)

Answer 2

我稍微更改了 Nahidur Ra​​hman 的代码，以使最低价格过滤器起作用，有必要从最低价格查询并应用最高价格过滤器。

def is_valid_queryparam(param):
    return param != '' and param is not None

def filter(request):
if request.GET:
    price_min = request.GET.get('priceMin')
    price_max = request.GET.get('priceMax')
    sort_by = request.GET.get("sort", "l2h")

    if is_valid_queryparam(price_min):
        if sort_by == "l2h":
            products = Product.objects.filter(price__gte=price_min).order_by('price')
        elif sort_by == "h2l":
            products = Product.objects.filter(price__gte=price_min).order_by('-price')
        else:
            products = Product.objects.filter(price__gte=price_min)
    else:
        products = Product.objects.all().order_by('price')

    if is_valid_queryparam(price_max):
        if sort_by == "l2h":
            products = products.filter(price__lte=price_max).order_by('price')
        elif sort_by == "h2l":
            products = products.filter(price__lte=price_max).order_by('-price')
        else:
            products = products.filter(price__lte=price_max)
    else:
        products = products
else:
    products = Product.objects.all().order_by('price')

paginator = Paginator(products, 9)
page = request.GET.get('page')
paged_products = paginator.get_page(page)
product_count = products.count()

context = {
    'products': paged_products,
    'product_count': product_count,
}
return render(request, 'store.html', context)