public function nav_list()

    {

        $this->load->database();

        /*

        测试demo json传值

        $query = $this->db->query('select nav_name,nav_desc from nav');

        $row = $query->result_array();

        $json = json_encode($row);

        echo $json;

        */

        /**

         * 异步加载

         */    

        $id = isset($_POST['id']) ? intval($_POST['id']) : 0;

        $result = array();

        $query = $this->db->query("select id,nav_name,nav_desc,pid from nav where pid =$id");

        foreach($query->result_array() as $row)

        {

            $node = array();

            $node['id'] = $row['id'];

            $node['text'] = $row['nav_desc'];

            $node['state'] = $this->has_child($row['id']) ? 'closed' : 'open';

            array_push($result,$node);

        }    

        echo json_encode($result);

    }

    public function has_child($id)

    {

        $this->load->database();

        $query = $this->db->query("select pid from nav where pid=$id");

        $row = $query->num_rows();

        return $row > 1 ? true : false;

    }

        <!-- 导航 -->

        <ul id="nav"  class="easyui-tree"  url="nav_list">

        </ul>