UpdateView

class ModelFormView(FormView):
    """ Use (?P<id>[\-0-9]*) urls.py lookups to populate form instance """

    lookups = ['id', ]

    def get_form_kwargs(self):
       """ Override to add instance """
        self.get_instance()
        kwargs = {'initial': self.get_initial()}
        if self.request.method in ('POST', 'PUT'):
            kwargs.update({
                'instance': self.instance,
                'data': self.request.POST,
                'files': self.request.FILES,
            })
        return kwargs

    def get_instance(self):
        """ Add in self.lookups list of attributes to search for instance """
        model = self.get_form_class()._meta.model
        for lookup in self.lookups:
            look = self.kwargs.get(lookup, '')
            if look:
                try:
                    self.instance = model.objects.get(*((lookup, look),))
                    self.pk = self.instance.pk
                    return self.pk
                except ObjectDoesNotExist:
                    self.instance = None
                                                                                                                          
        return 0