Question

In Django/Python, when you make a custom form, does it need to have a clean() method, or will calling .is_valid() perform a default validation?

if request.method == 'POST':
        filter = FilterForm(request.POST)
        if filter.is_valid():
            print 'Month is ' + filter.cleaned_data['month']
            print 'Type is ' + filter.cleaned_data['type']
            print 'Number is ' +filter.cleaned_data['number']
        else:
            print 'Invalid form'
            print filter.errors

“Invalid Form” gets printed but no errors get printed.

class FilterForm(forms.Form):
    months = [('January','January'),
                  ('February','February'),
                  ('March','March'),
                  ('April','April'),
                  ('May','May'),
                  ('June','June'),
                  ('July','July'),
                  ('August','August'),
                  ('September','September'),
                  ('October','October'),
                  ('November','November'),
                  ('December','December'),]
    types = [('text','Text'),
                 ('call','Call'),] 

    month = forms.ChoiceField(months)
    type = forms.ChoiceField(choices=types,widget=forms.CheckboxSelectMultiple)

    def __init__(self,numbers,*args, **kwargs):
        super(FilterForm,self).__init__(*args, **kwargs)
        self.fields['number'] = forms.ChoiceField(choices=numbers)

    def clean(self):
        return self.cleaned_data

I’ve tried it with and without the clean method.

Answer 1

does it need to have a clean() method

No. Completely optional.

There’s a big list of things that Django does in a specific order when it validates forms. You can learn about the process here:

http://docs.djangoproject.com/en/dev/ref/forms/validation/

As for finding your problem, if you stick a {{form.errors}} on your template, you’ll see which field is blowing up. I have a feeling it could be that your choices is defined in a place that something can’t get a handle on when it needs to (Move them out of the class).

Edit: Almost missed this. Look at this line:

def __init__(self,numbers,*args, **kwargs)

And then look at this line:

filter = FilterForm(request.POST)

You need to pass the numbers argument in this time too. It’s a completely new instance. it can’t validate because it doesn’t know what numbers is.