A Django gCBV mixin that validates unboung (GET) forms

mixins.py

def _initial_to_data(form):
    """
    Given a form, convert its initial data into a dict that can simulate
    the request.POST that would be generated if that form was submitted as-is.

    This will respect the form's prefix and will convert all field values to
    strings.
    """
    return {f.html_name: f.value() for f in form}


class PreValidateFormMixin(object):
    """
    Performs validation on unbound forms using their initial data.
    """
    def get_form(self, *args, **kwargs):
        form = super(PreValidateFormMixin, self).get_form(*args, **kwargs)
        if form.is_bound:
            return form

        kwargs = self.get_form_kwargs()
        kwargs['data'] = _initial_to_data(form)
        form_copy = form.__class__(**kwargs)
        if form_copy.is_valid():
            return form
        else:
            return form_copy