title: Django forms clean data
body: <p>I'm trying to clean data in using clean method in forms, but when I did it then I dont see validation errors in my form its only error page from django.</p>
  
  <p>I have edit and create form and I would like to have this clean in one place but not copy to 2 views.</p>
  
  <p>Can you give me some advice?
  I read docs about clean and valid in forms but I have still problems with that. I give example of it:</p>
  
  <p><strong>Views.py</strong></p>
  
  <pre><code>@user_passes_test(lambda u: u.is_staff, login_url='/account/login/')
  def client_create(request):
  
      dict = {}
  
      if request.method == 'POST':
          form_user = ClientUserCreateForm(request.POST, prefix="user")
          form_client = ClientForm(request.POST, prefix="client")
          if form_user.is_valid() and form_client.is_valid():
              obj_user = form_user.save(commit=False)
              obj_client = form_client.save(commit=False)
  
              obj_user.username = form_client.cleaned_data['vat']
              obj_user.set_password(form_client.cleaned_data['vat'])
              obj_user.is_active = 1
              obj_user.save()
  
              obj_client.id_id = obj_user.id
              obj_client.save()
  
                  # Redirect to Client profile
                  return HttpResponseRedirect(reverse('client_profile', args={obj_client.id_id}))
  
          # If forms have error show view again with errors
          dict['form_user'] = form_user
          dict['form_client'] = form_client
          return render(request, 'panel/client/form.html', dict)
      else:
          dict['form_user'] = ClientUserCreateForm(prefix="user")
          dict['form_client'] = ClientForm(prefix="client")
          return render(request, 'panel/client/form.html', dict)
  </code></pre>
  
  <p><strong>Forms.py</strong></p>
  
  <pre><code>class ClientUserCreateForm(forms.ModelForm):
      first_name = forms.CharField(required=True)
      last_name = forms.CharField(required=True)
      email = forms.CharField(required=True)
  
      class Meta:
          model = User
          fields = ('first_name', 'last_name', 'email')
  
      def __init__(self, *args, **kwargs):
          super(ClientUserCreateForm, self).__init__(*args, **kwargs)
          self.fields['first_name'].widget.attrs.update({
              'type': 'text',
              'class': 'form-control',
              'id': 'input-text',
          })
          self.fields['last_name'].widget.attrs.update({
              'type': 'text',
              'class': 'form-control',
              'id': 'input-text',
          })
          self.fields['email'].widget.attrs.update({
              'type': 'text',
              'class': 'form-control',
              'id': 'input-text',
          })
  
      def clean(self):
          data = self.cleaned_data
  
          first_name = data.get('first_name')
          last_name = data.get('last_name')
          email = data.get('email')
  
          data['first_name'] = first_name[0].upper() + first_name[1:].lower()
          data['last_name'] = last_name[0].upper() + last_name[1:].lower()
          data['email'] = email.lower()
  
          return data
  
  
  class ClientForm(forms.ModelForm):
      tags = forms.CharField(widget=forms.Textarea, required=False)
  
      class Meta:
          model = Client
          fields = ('address', 'zip_code', 'city', 'country', 'forwarding_address',
                    'forwarding_zip_code', 'forwarding_city', 'forwarding_country',)
  
      def __init__(self, *args, **kwargs):
          super(ClientForm, self).__init__(*args, **kwargs)
          self.fields['country'].queryset = CountriesChoices.objects.all()
          self.fields['forwarding_country'].queryset = CountriesChoices.objects.all()
          self.fields['country'].initial = 1
          self.fields['address'].widget.attrs.update({
              'type': 'text',
              'class': 'form-control',
              'id': 'input-text',
          })
          self.fields['zip_code'].widget.attrs.update({
              'type': 'text',
              'class': 'form-control',
              'id': 'input-text',
          })
          self.fields['city'].widget.attrs.update({
              'type': 'text',
              'class': 'form-control',
              'id': 'input-text',
          })
          self.fields['country'].widget.attrs.update({
              'class': 'form-control',
          })
  
  
      def clean(self):
          data = self.cleaned_data
  
          address = data.get('address')
          zip_code = data.get('zip_code')
          city = data.get('city')
          forwarding_address = data.get('forwarding_address')
          forwarding_zip_code = data.get('forwarding_zip_code')
          forwarding_city = data.get('forwarding_city')
  
          data['address'] = address[0].upper() + address[1:].lower()
          data['zip_code'] = zip_code
          data['city'] = city[0].upper() + city[1:].lower()
  
          if len(forwarding_address) &gt; 0:
              data['forwarding_address'] = forwarding_address[0].upper() + forwarding_address[1:].lower()
          else:
              data['forwarding_address'] = address[0].upper() + address[1:].lower()
  
          if len(forwarding_zip_code) &gt; 0:
              data['forwarding_zip_code'] = forwarding_zip_code
          else:
              data['forwarding_zip_code'] = zip_code
  
          if len(forwarding_city) &gt; 0:
              data['forwarding_city'] = forwarding_city[0].upper() + forwarding_city[1:].lower()
          else:
              data['forwarding_city'] = city[0].upper() + city[1:].lower()
  
          return data
  </code></pre>
  
  <p>For example i leave field "first_name" empty and then i got error django page with: 'NoneType' object is not subscriptable(traceback below) except form page with error "This field is required"(when i comment clean method).</p>
  
  <p><strong>Traceback</strong></p>
  
  <pre><code>Environment:
  
  
  Request Method: POST
  Request URL: http://127.0.0.1:8000/panel/client/edit/6/
  
  Django Version: 1.8.8
  Python Version: 3.5.1
  Installed Applications:
  ('django.contrib.admin',
   'django.contrib.auth',
   'django.contrib.contenttypes',
   'django.contrib.sessions',
   'django.contrib.messages',
   'django.contrib.staticfiles',
   'core',
   'api',
   'client',
   'registration',
   'avatar',
   'filer',
   'mptt',
   'easy_thumbnails',
   'reversion')
  Installed Middleware:
  ('django.contrib.sessions.middleware.SessionMiddleware',
   'django.middleware.common.CommonMiddleware',
   'django.middleware.csrf.CsrfViewMiddleware',
   'django.contrib.auth.middleware.AuthenticationMiddleware',
   'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
   'django.contrib.messages.middleware.MessageMiddleware',
   'django.middleware.clickjacking.XFrameOptionsMiddleware',
   'django.middleware.security.SecurityMiddleware')
  
  
  Traceback:
  File "C:\Users\loc\dJangoEnvironment\lib\site-packages\django\core\handlers\base.py" in get_response
    132.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\loc\dJangoEnvironment\lib\site-packages\django\contrib\auth\decorators.py" in _wrapped_view
    22.                 return view_func(request, *args, **kwargs)
  File "C:\Users\loc\PycharmProjects\pro\core\views.py" in client_edit
    192.         if form_user.is_valid() and form_client.is_valid():
  File "C:\Users\loc\dJangoEnvironment\lib\site-packages\django\forms\forms.py" in is_valid
    184.         return self.is_bound and not self.errors
  File "C:\Users\loc\dJangoEnvironment\lib\site-packages\django\forms\forms.py" in errors
    176.             self.full_clean()
  File "C:\Users\loc\dJangoEnvironment\lib\site-packages\django\forms\forms.py" in full_clean
    393.         self._clean_form()
  File "C:\Users\loc\dJangoEnvironment\lib\site-packages\django\forms\forms.py" in _clean_form
    417.             cleaned_data = self.clean()
  File "C:\Users\loc\PycharmProjects\pro\core\forms.py" in clean
    421.         data['first_name'] = first_name[0].upper() + first_name[1:].lower()
  
  Exception Type: TypeError at /panel/client/edit/6/
  Exception Value: 'NoneType' object is not subscriptable
  </code></pre>