symfony - Form: I don't get errors when I submit wrong data -

i have controller code validate form (i'm using ajax reques). problem: dont error when submit wrong data, can see in output belower:

$app->post('/contacto', function (request $request) use ($app) {       $form = $app['form.factory']->createbuilder('form', $data)         ->add('nombre', 'text', array(             'constraints' => new assert\notblank(array('message' => 'el campo nombre es obligatorio'))         ))         ->add('email', 'text', array(             'required' => false,             'constraints' => new assert\email(array('message' => 'has introducido un email no válido. revísalo, por favor.')),         ))         ->add('telefono', 'text', array(             'label' => 'teléfono',             'constraints' => array(                 new assert\regex(array('pattern' => "/^(?:\d\s*){8}\d$/", 'message' => 'el teléfono debe tener 9 dígitos')),                 new assert\notblank(array('message' => 'el campo teléfono es obligatorio')),             )))             ->add('texto', 'textarea', array(                 'constraints' => new assert\notblank(array('message' => 'el campo texto es obligatorio')),                 'attr' => array('cols' => '76', 'rows' => '8'),             ))             ->getform();      $post = $request->request->get('form');      $form->bind($post);      if ($form->isvalid()) {         $data = $form->getdata();           $app['mailer']->send($message);          $my_array = array('gracias, hemos recibido tu mensaje, te contactaremos lo antes posible');          return new response('true');     } else {         var_dump($form->getdata());         var_dump($form->geterrors());         die("jfklas");         return new response(json_encode($form));     } }); 

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array(4) {   ["nombre"]=>   string(8) "fasdfasd"   ["email"]=>   string(5) "fasdf"   ["telefono"]=>   string(7) "9999999"   ["texto"]=>   string(7) "fasdfas" } array(0) { } jfklas 

$form->geterrors() return returns errors of form itself, , not errors child fields. can errors if specify field, example $form['telefono']->geterrors() or using $form->geterrorsasstring()