My Upload button doesnt show

Hello @evan0014 and welcome to our forums

From the code that I can see the field names are not the correct ones. They all need to be the ones that are from the database name and not the displayed ones. More specifically instead of having:

->fields('Barang', 'Harga', 'Deskripsi','Gambar');

should change to:

->fields('barang', 'harga', 'deskripsi','gambar'); 

(all lowercases)

same goes for the field_upload, instead of having:

->set_field_upload('Gambar', 'assets/uploads/poster');

you should have:

 ->set_field_upload('gambar', 'assets/uploads/poster');