Using custom_result_object

Hi!

I'm trying to figure out how to use the "custom_result_object" and I need something which is very similar to the example in the documentation. The date is stored in a table as a unix timestamp and would like to have it returned as a human readable date.

https://codeigniter.com/user_guide/datab...lt-objects

So I figured I'd give "custom_result_object" a try because it could come in handy in some other spots.

Model:

PHP Code:

public function get_shortlink_list($team = 0, $order = 0, $limit = 0, $offset = 0) {
        $this->db->where('owner',$this->session->usr_id);

        if($order)
            $this->db->order_by($order);

        if($limit)
            $this->db->limit($limit,$offset);

        $data = $this->db->get('entries');

        if($data->num_rows() > 0) {
            require(APPPATH.'/models/custom_results/Shortlink_List.php');

            return $data->custom_result_object('Shortlink_List');
        }

        return false;
    } 


The Shortlink_List.php contains:

PHP Code:

<?php

defined('BASEPATH') OR exit('No direct script access allowed');

class Shortlink_list {

    public $id;
    public $url;
    public $custom;

    protected $timestamp;

    public function timestamp($format)
    {
        return $this->timestamp->format($format);
    }

    public function __set($name, $value)
    {
        if ($name === 'timestamp')
        {
            $this->timestamp = DateTime::createFromFormat('U', $value);
        }
    }

    public function __get($name)
    {
        if (isset($this->$name))
        {
            return $this->$name;
        }
    }
} 


The part of the controller using this:

PHP Code:

public function links() {
        
        $result = $this->shortlink->get_shortlink_list();
        
        foreach($result as $row) {
            echo $row->id.':';
            echo $row->timestamp('Y-m-d').'<br />';

        }

    } 


The result I'm getting is: 

Fatal error: Call to a member function format() on string in

Even though I've followed the example in the documentation very closely. Any ideas / hints would be appricated.

Thanks,

jay