从推到顶部的页面更改后，不会产生 Flutter Bloc State

Question

AddWorkoutEvent 已从 PageCreateWorkout[= 正确调度47=] DbMWorkout.

这将被插入到数据库的正确 table 中。 PageCreateWorkout 将收到 WorkoutAddedState 通知使用给定的 workoutId 到 PageWorkoutDetail。路由堆叠在PageSelectWorkout上，其中WorkoutBloc 主要用于显示所有锻炼。在那里 PageSelectWorkout 应该用新的 WorkoutLoadedState 和新给定的刷新锻炼列表。（WorkoutList 包含添加的 Workout，我在记录器中检查过；但不会产生 State。请注意，我将 equatable 扩展到 WorkoutStates。）

else if (event is AddWorkoutEvent) { logger.i("AddWorkoutEvent | workout: ${event.workout}"); yield WorkoutLoadingState(); try { DbMWorkout workout = await RepositoryWorkout.repo.add(event.workout); yield WorkoutAddedState(id: workout.id); List<DbMWorkout> workoutList = await RepositoryWorkout.repo.getAll(); logger.i("AddWorkoutEvent | workoutListLength: ${workoutList.length}"); yield WorkoutLoadedState(workoutList: workoutList); // <-- this state } catch (e) { yield WorkoutErrorState(message: e.toString()); } }

PageSelectWorkout 是 indexedStack 中导航器的初始页面：

IndexedStack( sizing: StackFit.expand, index: _currentIndex, children: <Widget>[ Navigator( key: _pageOverview, initialRoute: PageOverview.routeName, onGenerateRoute: (route) => RouteGenerator.generateRoute(route)), Navigator( key: _pageSelectWorkoutNew, initialRoute: PageSelectWorkout.routeName, onGenerateRoute: (route) => RouteGenerator.generateRoute(route)), Navigator( key: _pageLog, initialRoute: PageLog.routeName, onGenerateRoute: (route) => RouteGenerator.generateRoute(route)), Navigator( key: _pageSettings, initialRoute: PageSettings.routeName, onGenerateRoute: (route) => RouteGenerator.generateRoute(route)) ]),

到 SelectWorkout 的命名路由在 BlocProvider 中用正确的 Bloc 包装：

case PageSelectWorkout.routeName: return CupertinoPageRoute( settings: settings, builder: (context) { return BlocProvider( create: (context) => WorkoutBloc(), child: PageSelectWorkout()); });

注意：在 DeleteWorkoutEvent 等其他事件中，在没有导航到另一个页面的情况下发生，更新后的状态会正确生成。

Answer 1

我在检查了一些 GitHub 问题后找到了答案，答案很简单：因为我想在 2 个不同的页面上访问同一个 Bloc，所以我不能只是将 Bloc 的新实例包装到每个页面。

相反，我应该将 BlocProvider 与 WorkoutBloc 包装在 WidgetTree 层次结构中更高的位置，例如 main.dart

之前：

case PageSelectWorkout.routeName:
    return CupertinoPageRoute(
        settings: settings,
        builder: (context) => BlocProvider(
            create: (context) => WorkoutBloc(), // <-- Instance of WorkoutBloc
            child: PageSelectWorkout()));

  case PageCreateWorkout.routeName:
    return CupertinoPageRoute(
        settings: settings,
        builder: (context) => BlocProvider(
              create: (context) => WorkoutBloc(), // <-- Instance of WorkoutBloc
              child: PageCreateWorkout(
                workoutIndex: arguments["workoutIndex"],
                workoutPosition: arguments["workoutPosition"],
              ),
            ));

之后：

case PageSelectWorkout.routeName:
    return CupertinoPageRoute(
        settings: settings, builder: (context) => PageSelectWorkout());

  case PageCreateWorkout.routeName:
    return CupertinoPageRoute(
      settings: settings,
      builder: (context) => PageCreateWorkout(
        workoutIndex: arguments["workoutIndex"],
        workoutPosition: arguments["workoutPosition"],
      ),
    );

及 Inheritance/WidgetTree 层次结构中的更高级别，例如main.dart :

return MaterialApp(
                  debugShowCheckedModeBanner: false,
                  title: Strings.appTitle,
                  theme: AppTheme.darkTheme,
                  home: MultiBlocProvider(providers: [
                    BlocProvider<WorkoutBloc>(
                      create: (context) => WorkoutBloc(), // <-- put the Instance higher
                    ),
                    BlocProvider<NavigationBloc>(
                      create: (context) => NavigationBloc(),
                    ),
                  ], child: BottomNavigationController()));

从推到顶部的页面更改后，不会产生 Flutter Bloc State

Flutter Bloc State won't be yielded after change from the Page pushed on top

dart

flutter

bloc

flutter-bloc