构建期间调用的 Flutter Provider setState() 或 markNeedsBuild()

我想加载事件列表，并在获取数据时显示加载指示器.

我正在try Provider模式(实际上是重构现有的应用程序).

因此，根据提供程序中管理的状态，事件列表显示是有条件的.

问题是，当我太快地拨打notifyListeners()时，会得到这样的异常:

═异常被基础库═捕获

为EventProvider调度通知时引发以下断言:

在生成过程中调用setState()或markNeedsBuild().

...

发送通知的EventProvider是:"EventProvider"的实例

═

在调用notifyListeners()之前等待几毫秒即可解决问题(请参阅下面Provider类中的注释行).

这是一个基于我的代码的简单示例(希望不要过于简化):

main function :

Future<void> main() async {
    runApp(
        MultiProvider(
            providers: [
                ChangeNotifierProvider(create: (_) => LoginProvider()),
                ChangeNotifierProvider(create: (_) => EventProvider()),
            ],
            child: MyApp(),
        ),
    );
}

root widget:

class MyApp extends StatelessWidget {

    @override
    Widget build(BuildContext context) {
        final LoginProvider _loginProvider = Provider.of<LoginProvider>(context, listen: true);
        final EventProvider _eventProvider = Provider.of<EventProvider>(context, listen: false);

        // load user events when user is logged
        if (_loginProvider.loggedUser != null) {
            _eventProvider.fetchEvents(_loginProvider.loggedUser.email);
        }

        return MaterialApp(
            home: switch (_loginProvider.status) { 
                case AuthStatus.Unauthenticated:
                    return MyLoginPage();
                case AuthStatus.Authenticated:
                    return MyHomePage();
            },
        );

    }
}

home page:

class MyHomePage extends StatelessWidget {

    @override
    Widget build(BuildContext context) {
        final EventProvider _eventProvider = Provider.of<EventProvider>(context, listen: true);

        return Scaffold(
            body: _eventProvider.status == EventLoadingStatus.Loading ? CircularProgressIndicator() : ListView.builder(...)
        )
    }
}

event provider:

enum EventLoadingStatus { NotLoaded, Loading, Loaded }

class EventProvider extends ChangeNotifier {

    final List<Event> _events = [];
    EventLoadingStatus _eventLoadingStatus = EventLoadingStatus.NotLoaded;

    EventLoadingStatus get status => _eventLoadingStatus;

    Future<void> fetchEvents(String email) async {
        //await Future.delayed(const Duration(milliseconds: 100), (){});
        _eventLoadingStatus = EventLoadingStatus.Loading;
        notifyListeners();
        List<Event> events = await EventService().getEventsByUser(email);
        _events.clear();
        _events.addAll(events);
        _eventLoadingStatus = EventLoadingStatus.Loaded;
        notifyListeners();
    }
}

有人能解释一下发生了什么事吗？