public function editAction($id)
    {
        $instance = $this->getManager()->find($id);
        if(!$instance) {
            return new RedirectResponse($this->generateUrl('ringo_php_redmon'));
        }
        $form = $this->getForm($instance);
        return $this->render(
            $this->getTemplatePath().'edit.html.twig',
            array(
                'form' => $form->createView(),
                'id'   => $id,
                'errors' => array()
            )
        );
    }