how to avoid a QTreeView -"setUpdatesEnabled(false)" from erasing itself before restore with "setUpdatesEnabled(true)"

I use a QTreeView with QStandartItemModel,I trigger a Dlg that will change the QStandartItemModel underling structure. So I need temporarily prevent view to update which in turn call QStandartItemModel ‘s index() or sth need to read data from the underling the structure . But when I call QTreeView -“setUpdatesEnabled(false)” before the DLg.exec(). the View is erased? how can I stop view to update but not erase it? Regards!