Force Reload page in CupertinoTabView in Flutter

Question

When user taps on an item in CupertinoTabView, I want to reload the page everytime. Right now, it loads only for the first time. Next time onwards it just displays the previous state. I want to force reload it. For example, when user taps on pageThree, which is 'case 2' in switch case in the code below, I want to reload that page.

Here's my code :

class HomeScreen extends StatelessWidget {

  int currentIndex = 0;
  final GlobalKey<NavigatorState> pageOneTabNavKey = GlobalKey<NavigatorState>();
  final GlobalKey<NavigatorState> pageTwoTabNavKey = GlobalKey<NavigatorState>();
  final GlobalKey<NavigatorState> pageThreeTabNavKey = GlobalKey<NavigatorState>();
  final GlobalKey<NavigatorState> pageFourTabNavKey = GlobalKey<NavigatorState>();
  final GlobalKey<NavigatorState> pageFiveTabNavKey = GlobalKey<NavigatorState>();
  @override
  Widget build(BuildContext context) {
    return CupertinoTabScaffold(
        tabBar: CupertinoTabBar(
            activeColor: AppColor.pumpkinOrange,
            inactiveColor: Colors.white,
            backgroundColor: AppColor.peacockBlue,
            items: const <BottomNavigationBarItem>[
              BottomNavigationBarItem(
                icon: Icon(Icons.home)
              ),
              BottomNavigationBarItem(
                icon: Icon(Icons.notifications_none),
              ),
              BottomNavigationBarItem(
                icon: Icon(Icons.star_border),
              ),
              BottomNavigationBarItem(
                icon: Icon(Icons.person),
              ),
              BottomNavigationBarItem(
                icon: Icon(Icons.help_outline),
              )
            ],
          onTap: (index) {

              switch (index) {
                case 0:
                  pageOneTabNavKey.currentState.popUntil((r) => r.isFirst);
                  break;
                case 1:
                  pageTwoTabNavKey.currentState.popUntil((r) => r.isFirst);
                  break;
                case 2:
                  pageThreeTabNavKey.currentState.popUntil((r) => r.isFirst);
                  break;
                case 3:
                  pageFourTabNavKey.currentState.popUntil((r) => r.isFirst);
                  break;
                case 4:
                  pageFiveTabNavKey.currentState.popUntil((r) => r.isFirst);
                  break;
              }

            currentIndex = index;

          },
        ),
        tabBuilder: (BuildContext context, int index) {
          return CupertinoTabView(builder: (BuildContext context) {
            switch (index) {
              case 0:
                return CupertinoTabView(
                  navigatorKey: summaryTabNavKey,
                  builder: (BuildContext context) {
                    return MultiBlocProvider(
                      providers: <BlocProvider>[
                        BlocProvider<PageOneBloc>(
                            create: (BuildContext context) =>
                            PageOneBloc(FetchDataRepository())..add(LoadingEvent())
                        ),
                        BlocProvider<DataBloc>(
                            create: (BuildContext context) => DataBloc()
                        )
                      ],
                      child: PageOne(),
                    );
                  },
                );
                break;
              case 1:
                return CupertinoTabView(
                  navigatorKey: pageTwoTabNavKey,
                  builder: (BuildContext context) {
                    return MultiBlocProvider(
                      providers: <BlocProvider>[
                        BlocProvider<PageTwoBloc>(
                          create: (BuildContext context) =>
                          PageTwoBloc(PageTwoManager())
                            ..add(LoadPageTwoEvent()),
                        ),
                        BlocProvider<ScrolleventnotifierBloc>(
                          create: (BuildContext context) =>
                              ScrolleventnotifierBloc(),
                        ),
                      ],
                      child: PageTwo(),
                    );
                  },
                );
                break;
              case 2:
                return CupertinoTabView(
                  navigatorKey: pageThreeTabNavKey,
                  builder: (BuildContext context) {
                    return BlocProvider<PageThreeBloc>(
                      create: (BuildContext context) =>
                      PageThreeBloc()..add(UserReachesPageThreeEvent(noOfItems:5,pageNumber: 1)),
                      child: PageThree(),
                    );
                  },
                );
                break;
              case 3:
                return CupertinoTabView(
                  navigatorKey: pageFourTabNavKey,
                  builder: (BuildContext context) {
                    return BlocProvider<ProfileBloc>(
                      create: (BuildContext context) =>
                      ProfileBloc()..add(UserReachesProfilePageEvent()),
                      child: ProfilePage(),
                    );
                  },
                );
                break;
              case 4:
                return CupertinoTabView(
                  navigatorKey: helpTabNavKey,
                  builder: (BuildContext context) {
                    return BlocProvider<HelpBloc>(
                      create: (BuildContext context) =>
                      HelpBloc(FetchHelpRepository())..add(HelpLoadEvent()),
                      child: HelpPage(),
                    );
                  },
                );
                break;
            }
            return Container();
          });
        });
  }
}

Answer 1

I am not sure what was problem in your given example, but I have changed the widget to StatefulWidget and it seems to be working. For the currentState on GlobalKey to not be null - widget must be Stateful.

Here is your code, slightly changed - https://codepen.io/pintom/pen/JjYVxbe

class _HomeScreenState extends State<HomeScreen> {
  final GlobalKey<NavigatorState> pageOneTabNavKey =
      GlobalKey<NavigatorState>();

  final GlobalKey<NavigatorState> pageTwoTabNavKey =
      GlobalKey<NavigatorState>();

  int currentIndex;

  @override
  Widget build(BuildContext context) {
    return CupertinoApp(
      home: CupertinoTabScaffold(
        tabBar: CupertinoTabBar(
          items: const <BottomNavigationBarItem>[
            BottomNavigationBarItem(
              icon: Icon(Icons.notifications_none),
            ),
            BottomNavigationBarItem(
              icon: Icon(Icons.star_border),
            ),
          ],
          onTap: (index) {
//            print('current i = $currentIndex, clicked = $index');

            if (index == currentIndex) {
              switch (index) {
                case 0:
                  pageOneTabNavKey.currentState.popUntil((r) => r.isFirst);
                  break;
                case 1:
                  pageTwoTabNavKey.currentState.popUntil((r) => r.isFirst);
                  break;
              }
            }

            currentIndex = index;
          },
        ),
        tabBuilder: (BuildContext context, int index) {
          currentIndex = index;

          return CupertinoTabView(
            builder: (BuildContext context) {
              switch (index) {
                case 0:
                  return CupertinoTabView(
                    navigatorKey: pageOneTabNavKey,
                    builder: (BuildContext context) {
                      return TabPage(index);
                    },
                  );
                  break;
                case 1:
                  return CupertinoTabView(
                    navigatorKey: pageTwoTabNavKey,
                    builder: (BuildContext context) {
                      return TabPage(index);
                    },
                  );
                  break;
                default:
                  return Container();
              }
            },
          );
        },
      ),
    );
  }
}