Django自定义验证导致视图返回None

我正在制作一个拍卖应用程序，需要检查表单上输入的出价金额是否等于或大于起始出价（如果有0个出价），或者是否大于当前出价

我使用clean（）进行自定义验证：

在views.py中：

def listing_page(request, listing_id):
    listing_selected = Listing.objects.get(pk=listing_id)
    if request.method == "POST":
        # Since I don't want the user to have to fill out a field specifying what listing page
        # they're on, and since I don't have access to that information in the model class
        # definition, I did that here:

        request.POST._mutable = True
        form = BidForm(request.POST)
        form.data['listing'] = listing_selected
        if form.is_valid():
            # ...process clean data...
            return HttpResponseRedirect(reverse('auctions:listing_page', args=(listing_id,)))

现在，当我使用此自定义验证正在检查的值提交表单时，我得到了“ValueError:view auctions.views.listing_页面没有返回HttpResponse对象，而是返回了None”。我检查了is_valid（）是否使用print语句计算为False。如果我提交了一个默认的无效值，如10.1111或“abcd”，我会收到正确的错误消息。当is_valid（）由于我的自定义验证而计算为False时，不应该发生这种情况吗？我错过了什么

编辑：根据要求，完整视图（我想我最初包括了所有相关部分，但谁知道呢）：

也可根据要求使用html：

<form class="bidform" action="{% url 'auctions:listing_page' listing.id %}" method="POST">
    {% csrf_token %}
    {{  form.amount  }}
    <input class="button bid_button" type="submit" value="Place Bid" name="make_bid">
</form>

---

如果我在is_valid（）调用中执行“单步执行”和“单步执行”，就会发生这种情况。为什么会这样做？

这是您的完整视图？向我们展示您的模板too@binpy我为您添加了整个视图。@BiploveLamichhane我为您添加了html。在html中，

，您的完整视图是

}

之后的

是什么too@binpy我为您添加了整个视图。@BiploveLamichhane我为您添加了html。在html中，
，在
POST
def listing_page(request, listing_id):
    listing_selected = Listing.objects.get(pk=listing_id)
    bids = Bid.objects.filter(listing=listing_selected)
    if request.method == "POST":
        if request.POST.get('add_to_watchlist') and request.user.is_authenticated:
            request.user.person.watchlist.add(listing_selected) 
            return HttpResponseRedirect(reverse('auctions:listing_page', args=(listing_id,)))
        elif request.POST.get('remove_from_watchlist') and request.user.is_authenticated:
            request.user.person.watchlist.remove(listing_selected)
            return HttpResponseRedirect(reverse('auctions:listing_page', args=(listing_id,)))
        elif (request.POST.get('close_listing') and request.user.is_authenticated 
        and request.user == listing_selected.user):
            listing_selected.active = False
            listing_selected.save()
            return HttpResponseRedirect(reverse('auctions:listing_page', args=(listing_id,)))
        elif request.POST.get('make_comment') and request.user.is_authenticated:
            comment_form = CommentForm(request.POST)
            if comment_form.is_valid():
                comment = Comment()
                comment.user = request.user
                comment.listing = listing_selected
                comment.comment = comment_form.cleaned_data['comment']
                comment.save()
                return HttpResponseRedirect(reverse('auctions:listing_page', args=(listing_id,)))
        elif request.POST.get('make_bid') and request.user.is_authenticated:
            request.POST._mutable = True
            form = BidForm(request.POST)
            form.data['listing'] = listing_selected
            if form.is_valid():
                bid = Bid()
                bid.listing = listing_selected
                bid.user = request.user
                bid.amount = form.cleaned_data['amount']
                bid.save()
                listing_selected.current_bid = bid
                listing_selected.save()
                request.session['bid_success_message'] = "Bid placed successfully."
                return HttpResponseRedirect(reverse('auctions:listing_page', args=(listing_id,)))
    else:
        form = BidForm()
        comment_form = CommentForm()
        winning = False
        if request.user.is_authenticated:
            person = Person.objects.filter(user=request.user).filter(watchlist=listing_selected)
        else: 
            person = False    
        if listing_selected.current_bid and listing_selected.current_bid.user == request.user:
            winning = True
        comments = Comment.objects.filter(listing=listing_selected)
        category = None
        if listing_selected.category:
            for value, label in Listing.Category.choices:
                if value == listing_selected.category:
                    category = label
        context = {
                "listing": listing_selected,
                "person": person,
                "num_bids": len(bids),
                "winning": winning,
                "form": form,
                "comment_form": comment_form,
                "comments": comments,
                "category": category
            }
        if "bid_fail_message" in request.session:
            message = request.session['bid_fail_message']
            del request.session['bid_fail_message']
            messages.error(request, message)
        if "bid_success_message" in request.session:
            message = request.session['bid_success_message']
            del request.session['bid_success_message']
            messages.success(request, message)
        return render(request, "auctions/listing_page.html", context)

<form class="bidform" action="{% url 'auctions:listing_page' listing.id %}" method="POST">
    {% csrf_token %}
    {{  form.amount  }}
    <input class="button bid_button" type="submit" value="Place Bid" name="make_bid">
</form>

class Listing(models.Model):

    def __str__(self):
        return f"Listing '{self.title}' created by user '{self.user.username}' \
                 on {self.time_created.date()}"