在 dispose 方法中访问 BlocProvider.of<Bloc>(context)

Question

有人知道我该怎么做吗？

我的代码：

  @override
  void dispose() {
    final FiltersBloc filtersBloc = 
       BlocProvider.of<FiltersBloc>(context);
    super.dispose();
  }

错误是：

flutter:         BlocProvider.of() called with a context that does not contain a Bloc of type FiltersBloc.
flutter:         No ancestor could be found starting from the context that was passed to
flutter: BlocProvider.of<FiltersBloc>().
flutter:
flutter:         This can happen if:
flutter:         1. The context you used comes from a widget above the BlocProvider.
flutter:         2. You used MultiBlocProvider and didn't explicity provide the BlocProvider types.
flutter:
flutter:         Good: BlocProvider<FiltersBloc>(builder: (context) => FiltersBloc())
flutter:         Bad: BlocProvider(builder: (context) => FiltersBloc()).
flutter:
flutter:         The context used was: FiltersDrawer(dirty, state: _FiltersDrawerState#86e8a)

另外，如果我按照错误代码并使用final filtersBloc = BlocProvider<FiltersBloc>(builder: (context) => FiltersBloc())，我将无法filtersBloc.dispatch()再调用。

我知道对于 initState，我们可以didChangeDependencies改为。但我找不到相当于处置的东西。

任何帮助将不胜感激。谢谢！

Answer 1

BlockProvider 需要初始化上下文。您可以在屏幕上对其进行初始化Widget build()

late FiltersBloc filtersBloc;

@override
Widget build(BuildContext context){
  filtersBloc = BlocProvider.of<FiltersBloc>(context);
  return ...
}

...然后调用所需的方法dispose()

late FiltersBloc filtersBloc;

@override
Widget build(BuildContext context){
  filtersBloc = BlocProvider.of<FiltersBloc>(context);
  return ...
}