@override
void didUpdateWidget(convariant MyWidget oldWidget) {
 super.didUpdateWidget(oldWidget);
 
 if (oldWidget.path != widget.path) {
 _pagingController.removePageRequestListener(_pageRequestListener!);
 _pageRequestListener = null;
 _pageRequestListener = (pageKey) async {
 // This is where we use viewModel.
 }
 _pagingController.addPageRequestListener(_pageRequestListener!);
 _pagingController.refresh();
 }
}