Q:

Django forms clean data

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.
I have edit and create form and I would like to have this clean in one place but not copy to 2 views.
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:
Views.py
@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)

Forms.py
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) > 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) > 0:
            data['forwarding_zip_code'] = forwarding_zip_code
        else:
            data['forwarding_zip_code'] = zip_code

        if len(forwarding_city) > 0:
            data['forwarding_city'] = forwarding_city[0].upper() + forwarding_city[1:].lower()
        else:
            data['forwarding_city'] = city[0].upper() + city[1:].lower()

        return data

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).
Traceback
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

A:

You should do validation like that in the individual clean_<fieldname> methods. Those will only be called if the content is already valid and populated. So:
def clean_firstname(self):
    first_name = self.cleaned_data['first_name']
    return first_name[0].upper() + first_name[1:].lower()

def clean_last_name(self):
    last_name = self.cleaned_data['last_name']
    return last_name[0].upper() + last_name[1:].lower()

def clean_email(self):
    email = self.cleaned_data['email']
    return email.lower()

Note also your first_name and last_name validation could be simplified by using last_name.capitalize(), which converts to exactly the format you want.

