Custom style plugin. Can't get raw data of field when selected more than one grouping field.

I've written quick hack, but still not sure if it could handle all situations.

<?php
  // ...

  function render() {
    $sets = $this->render_grouping($this->view->result, $this->options['grouping']);
    // Turn this all into an $options array for the jump menu.
    $this->view->row_index = 0;
    $fields = array();

    foreach ($sets as $title => $records) {
      // walk through groups and get rows
      $rows = $this->get_group_rows($records);
      // prepare objects for view
      foreach ($rows as $row_index => $row) {
        $this->view->row_index = $row_index;
        $fields[] = $this->view->style_plugin->get_field_value($this->view->row_index, $this->options['data_field']);
        $this->view->row_index++;
      }
    }
    unset($this->view->row_index);

    return var_export($fields, TRUE);
  }

  /**
   * Get rows from groups.
   */
  function get_group_rows($target) {
    $first = reset($target);
    // get rows if its a group
    if (is_array($first) && isset($first['group'])) {
      return $this->get_group_rows($first['rows']);
    }
    // return rows
    else {
      return $target;
    }
  }

  // ...
?>