mengatasi error pada php

 A PHP Error was encounteredSeverity: NoticeMessage: Undefined property: Data_barang::$uploadFilename: admin/Data_barang.phpLine Number: 29Backtrace: 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 encounteredType: ErrorMessage: Call to a member function do_upload() on nullFilename: C:\xampp\htdocs\toko_online\application\controllers\admin\Data_barang.phpLine Number: 29Backtrace: File: C:\xampp\htdocs\toko_online\index.php
 Line: 315
 Function: require_once