如何显示drupal菜单的子节点

在我的管理中，我启用了Show As Expanded复选框，但是子菜单没有显示。

$trail = menu_get_active_trail();
$leaf = $trail[1];
if(!empty($leaf['has_children'])) {
    $parameters = array(
        'active_trail' => array($leaf['plid']),
        'only_active_trail' => FALSE,
        'min_depth' => $leaf['depth'] + 1,
        'max_depth' => $leaf['depth'] + 2,
        'conditions' => array('plid' => $leaf['mlid']),
    );
    $children = menu_build_tree($leaf['menu_name'], $parameters);
    $vars['submenu'] = menu_tree_output($children); 
}

正确的代码是:

$trail = menu_get_active_trail();
$leaf = $trail[1];
if(!empty($leaf['has_children'])) {
    $parameters = array(
        'active_trail' => array($leaf['plid']),
        'min_depth' => $leaf['depth'] + 1,
        'max_depth' => $leaf['depth'] + 3,
        'conditions' => array('p1' => $leaf['mlid']),
    );
    $children = menu_build_tree($leaf['menu_name'], $parameters);
    $vars['submenu'] = menu_tree_output($children); 
}

谢谢。