Maybe I am missing something, but in symfony examples, in form submission action there's nothing which indicates form data is saved to database. (link). How can I save everything to db?

Example from the link:

public function executeSubmit($request)
{
  $this->forward404Unless($request->isMethod('post'));

  $params = array(
    'name'    => $request->getParameter('name'),
    'email'   => $request->getParameter('email'),
    'message' => $request->getParameter('message'),
  );

  $this->redirect('contact/thankyou?'.http_build_query($params));
}