public function postIndex(Request $req)
 {
     $this->validate($req, ['kode_gudang' => 'required|unique:ref_gudang', 'nm_gudang' => 'required']);
     $gd = ref_gudang::create($req->all());
     return redirect()->back()->withNotif(['label' => 'success', 'err' => 'Gudang berhasil dibuat dengan Kode. ' . $gd->kode_gudang]);
 }