One way to do it would be:
class CreateWizard(SessionWizardView):
file_storage = FileSystemStorage(location=os.path.join(settings.MEDIA_ROOT))
def done(self, form_list, **kwargs):
id = form_list[0].cleaned_data['id']
try:
thing = Thing.objects.get(pk=id)
instance = thing
except:
thing = None
instance = None
if thing and thing.user != self.request.user:
raise HttpResponseForbidden()
if not thing:
instance = Thing()
for form in form_list:
for field, value in form.cleaned_data.iteritems():
setattr(instance, field, value)
instance.user = self.request.user
instance.save()
return render_to_response('wizard-done.html', {
'form_data': [form.cleaned_data for form in form_list],})