/**
  * Delete a single custom option contained in the page or tab.
  *
  * @since 0.4.0
  * @param string $handle The element handle.
  */
 protected function _delete_single_field($handle)
 {
     ev_delete_option($handle);
 }
 /**
  * When the page is refreshed, save the custom data contained in the admin page.
  *
  * @since 0.1.0
  * @param string $group The group of the page that is being saved.
  */
 public function save($group = '')
 {
     /* This should run on admin only. */
     if (!is_admin()) {
         return;
     }
     /* Verify that we're submitting any data. */
     if (empty($_POST)) {
         return;
     }
     /* Verify the validity of the supplied nonce. */
     $nonce = isset($_POST['nonce']) ? $_POST['nonce'] : '';
     $action = 'ev_admin_page';
     $is_valid_nonce = wp_verify_nonce($nonce, $action);
     /* Check the user has the capability to save the page. */
     $is_valid_cap = current_user_can($this->capability());
     /* Exit if the nonce is invalid or the user doesn't have the required capability to save the page. */
     if (!$is_valid_nonce || !$is_valid_cap) {
         return;
     }
     $elements = $this->elements();
     if (!empty($elements)) {
         foreach ($elements as $index => $element) {
             if ($element['type'] === 'group' && $element['handle'] === $group) {
                 foreach ($element['fields'] as $field) {
                     if (!ev_is_skipped_on_saving($field['type'])) {
                         if (!isset($_POST[$field['handle']])) {
                             ev_delete_option($field['handle']);
                         } else {
                             $this->_save_single_field($field, $_POST[$field['handle']]);
                         }
                     }
                 }
                 break;
             } else {
                 if (!ev_is_skipped_on_saving($element['type'])) {
                     if (!isset($_POST[$element['handle']])) {
                         ev_delete_option($element['handle']);
                     } else {
                         $this->_save_single_field($element, $_POST[$element['handle']]);
                     }
                 }
             }
         }
         $type = 'success';
         $message = apply_filters('ev_save_options_tab_response_message', __('All saved!', 'ev_framework'), $type);
         $heading = apply_filters('ev_save_options_tab_response_heading', '', $type);
         $args = apply_filters("ev_save_options_tab_response_args[tab:{$group}]", array());
         ev_ajax_message($message, $type, $heading, $args);
     }
 }