多级下拉菜单

/*
 * 权限分组目录树
 */
public function getGroupTree(){
    $data = $this->select();
    $arrOptions = array();
    $this->getOptions($data, 0, $arrOptions, 0);
    $strOptions = implode('', $arrOptions);
    return '<select name="user_role">'.$strOptions.'</select>';
}

private function getOptions($data, $pid, &$arrOptions, $level){
    foreach ($data as $v){
        if($v['pid']==$pid){
            $arrOptions[] = $this->getHtmlOption($v['name'], $v['id'], $level);
            $this->getOptions($data, $v['id'], $arrOptions, $level+1);
        }
    }
}


private function getHtmlOption($name, $id, $level){
    $pxValue = 10*$level;
    $option = '<option value="'.$id.'" style="padding-left: '.$pxValue.'px">' . $name . '</option>';
    return $option;
}