protected function validateRequestParameters(Request $request)
    {
        $data = $request->request->all();
        if (isset($data['id'])) {
            unset($data['id']);
        }

        // we explicitly do not load existing data; an edit is a PUT and should supply all valid data!
        $this->form->submit($data);
        if (!$this->form->isValid()) {
            throw new BadRequestHttpException($this->form->getErrorsAsString());
        }

        return $this->form;
    }