Dodawanie walidacji podczas budowania forma

 ->add('field_name', 'integer', array(
     'label' => 'Your label here', 
     'data' => 0, // default value
     'precision' => 0, // disallow floats
     'constraints' => array(
         new Assert\NotBlank(), 
         new Assert\Type('integer'), 
         new Assert\Regex(array(
             'pattern' => '/^[0-9]\d*$/',
             'message' => 'Please use only positive numbers.'
             )
         ),
         new Assert\Length(array('max' => 2))
     )
 ))