ThinkPHP中获得下上篇文章的函数

ThinkPHP中获得上下篇文章的函数，大家可以参考一下方法，稍微修改下就可以应用到其他网站上，方法一样！

//取得上下篇文章
function PrevNext($id, $name = '', $where = array(), $fields = 'id,title'){
	$array = array();
	$model = M($name);
	$map = array();
	$map = $where;
	$map['id'] = array('lt',$id);
	$prevL = $model->field($fields)->where($map)->order('id desc')->find(); //上篇
	if(!$prevL){
		$prevL['id'] = '';
		$prevL['title'] = '暂无';
	}
	$map['id'] = array('gt',$id);
	$nextL = $model->field($fields)->where($map)->order('id asc')->find(); //下篇
	if(!$nextL){
		$nextL['id'] = '';
		$nextL['title'] = '暂无';
	}
	$array['prev'] = $prevL;
	$array['next'] = $nextL;
	return $array;
}