Django基于类的视图：视图polls.views.ChoiceView未返回HttpResponse对象。它返回了None

Question

我是django的新手，我创建了一个基于函数的视图，为一个问题创建了选择。

def create_choice(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    if request.method == 'POST':
        form = ChoiceForm(request.POST)
        if form.is_valid():
            choice = form.save(commit=False)
            choice.question = question
            choice.save()
            return HttpResponseRedirect(urlresolvers.reverse('polls:detail', kwargs={'question_id':question_id}))
    else:
        form = ChoiceForm()
    context = {'form':form, 'question':question}
    return render(request, 'polls/add_choice.html', context)

然后我尝试将其转换为基于类的视图......

class ChoiceView(generic.DetailView):
    template_name = 'polls/add_choice.html'

    def get(self, request, *args, **kwargs):
        form = ChoiceForm()
        question_id = self.kwargs['pk']
        question = get_object_or_404(Question, pk=question_id)

        context = {'form':form, 'question':question}
        return render(request, 'polls/add_choice.html', context)

    def post(self, request, *args, **kwargs):
        form = QuestionForm(request.POST)
        if form.is_valid():
            choice = form.save(commit=False)
            choice.question = question
            choice.save()
            return HttpResponseRedirect(urlresolvers.reverse('polls:detail', kwargs={'question_id':question_id}))

但是当我在runserver中添加一个选项时，我得到“视图polls.views.ChoiceView没有返回一个HttpResponse对象。它返回了None。”我做错了什么？为什么我没有获得GET数据？