模型类

class User_model {
    private $id;

    public function __construct( stdClass $val )
    {
        $this->id = $val->id; 
        /* ... */
        /*
          The stdClass provided by CI will have one property per db column.
          So, if you have the columns id, first_name, last_name the value the 
          db will return will have a first_name, last_name, and id properties.
          Here is where you would do something with those.
        */
    }
}

class Usermanager extends CI_Model {
     public function __construct()
     {
          /* whatever you had before; */
          $CI =& get_instance(); // use get_instance, it is less prone to failure
                                 // in this context.
          $CI->load->helper(\"user_model_helper\");
     }

     public function by_id( $id )
     {
           $q = $this->db->from(\'users\')->where(\'id\', $id)->limit(1)->get();
           return new User_model( $q->result() );
     }
}

class User extend CI_Model 
{
    function by_id($id) {
        $this->db->select(\'*\')->from(\'users\')->where(\'id\', $id)->limit(1);
        // Your additional code goes here
        // ...
        return $user_data;
    }
}


class Home extend CI_Controller
{
    function index()
    {
        $this->load->model(\'user\');
        $data = $this->user->by_id($id);
    }
}