django-'NoneType' 对象不可调用

Question

重定向到结果页面时出现此错误。是不是因为在重定向页面中，“POST.get”函数在重定向之前无法获取用户在表单中输入的内容？

views.py

class InputFormView(FormView):
    template_name = 'inputform.html'
    form_class = InputForm

    def get_success_url(self):
        return ''.join(
        [
            reverse('result'),
            '?company=',self.request.POST.get('company'),
            '&region=',self.request.POST.get('region')  <is there anything wrong here---？       
        ]
        )


class ReulstView(FormView):
    context_object_name = 'result_list'
    template_name = 'result_list.html'
    model = Result

    if form.is_valid():
        company = form.cleaned_data['company']
        region = form.cleaned_data['region']

        self.queryset=Result.objects.filter(region=region)

        return render(request, 'result_list.html', {'form': form})

    def get_context_data(self, **kwargs):
        context = super(ReulstView, self).get_context_data(**kwargs)
        context["sales"] = self.get_queryset().aggregate(Sum('sales'))

        context["company"] = self.request.POST.get("company")
        context["region"] = self.request.POST.get("region")

        return context

    def get_queryset(self):
        return Result.objects.all()

追溯：

File "C:\Python27\lib\site-packages\django-1.8.3-py2.7.egg\django\core\handlers\base.py" in get_response
  132.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Python27\lib\site-packages\django-1.8.3-py2.7.egg\django\views\generic\base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)
File "C:\Python27\lib\site-packages\django-1.8.3-py2.7.egg\django\views\generic\base.py" in dispatch
  89.         return handler(request, *args, **kwargs)
File "C:\Python27\lib\site-packages\django-1.8.3-py2.7.egg\django\views\generic\edit.py" in get
  205.         form = self.get_form()
File "C:\Python27\lib\site-packages\django-1.8.3-py2.7.egg\django\views\generic\edit.py" in get_form
  74.         return form_class(**self.get_form_kwargs())

Exception Type: TypeError at /result_list/
Exception Value: 'NoneType' object is not callable

输入表单

class InputForm(forms.ModelForm):
    company=forms.CharField(widget=forms.TextInput, label="Company",error_messages={'required': 'Please enter the company name'},required=True)

    #region   This form can display correctly with drop down list
    iquery = Dupont.objects.values_list('region', flat=True).distinct()
    iquery_choices = [('', 'None')] + [(region,region)  for region in iquery]
    region = forms.ChoiceField(choices=iquery_choices)

对于同样的功能，我尝试了另一个代码，即使没有错误但无法显示表单数据，它显示为无。希望您能通过以下链接回答我的问题：

django- why after redirecting, the form display "None"

Answer 1

我认为这是您的问题：您使用的是FormView，但尚未定义要使用的表单类。在类上设置form_class attr，或者覆盖get_form_class 方法：

class ReulstView(FormView):
    context_object_name = 'result_list'
    template_name = 'result_list.html'
    model = Result
    form_class = InputForm

另外，form_valid 方法会接收表单实例，你不需要手动实例化它：

def form_valid(self, form, **kwargs):
    form = InputForm(self.request.POST)  # <- remove this line
    if form.is_valid():
    ...

Answer 2

让我们再写一个线程。 :) 获得“返回函数外”错误的唯一方法 - 您试图返回不是从函数中返回的东西。 :) 这通常是由于输入错误或缩进错误而发生的。 您能否提供出现此错误的代码？我认为那里的缩进有问题。

class ReulstView(FormView):
    context_object_name = 'result_list'
    template_name = 'result_list.html'
    model = Result

    if form.is_valid(): # <- it is not a function or method
                        #  it is a class declaration  
        company = form.cleaned_data['company']
        region = form.cleaned_data['region']

        self.queryset=Result.objects.filter(region=region)

        return render(request, 'result_list.html', {'form': form})
     def get_context_data(self, **kwargs): #<- and this is a method
        #... all your following code

我不熟悉 Django FormViews，但看起来正确的代码可能是这样的：

class ResultView(FormView):
    context_object_name = 'result_list'
    template_name = 'result_list.html'
    model = Result

    def form_valid(self, form):
        company = form.cleaned_data['company']
        region = form.cleaned_data['region']
        self.queryset=Result.objects.filter(region=region)    
        return render(request, 'result_list.html', {'form': form})

Answer 3

问题可能出在您的 forms.py 文件上。当您在 forms.py 文件中导入和使用模型时，您正在使用括号来定义您不应该使用的模型。例如，如果您的模型是假设 Post， 应该定义为Post 而不是Post()