Views with custom filter and fields [closed]

Question

I have crated a custom view and add some fields from database by these code but whenever i am using string fields and filter it gives me error "Broken/missing handler"

$data['coupons']['name'] = array(
    'title' => t('Name'),
    'help' => t('Name of coupon.'),
    'field' => array(
       'handler' => 'views_handler_field_string',
     ),
      'sort' => array(
       'handler' => 'views_handler_sort',
      ),
      'filter' => array(
        'handler' => 'views_handler_filter_string',
      ),
   );

This problem is appear whenever i am fetching string type data from database. please help me, Thanks in advanced :)