mengatasi error pada php

A PHP Error was encountered

Severity: Notice

Message: Undefined property: Data_barang::$upload

Filename: admin/Data_barang.php

Line Number: 29

Backtrace:

File: C:\xampp\htdocs\toko_online\application\controllers\admin\Data_barang.php

Line: 29

Function: _error_handler

File: C:\xampp\htdocs\toko_online\index.php

Line: 315

Function: require_once

An uncaught Exception was encountered

Type: Error

Message: Call to a member function do_upload() on null

Filename: C:\xampp\htdocs\toko_online\application\controllers\admin\Data_barang.php

Line Number: 29

Backtrace:

File: C:\xampp\htdocs\toko_online\index.php

Line: 315

Function: require_once