收到新事件时，Flutter Bloc取消跑步活动

发布于 2025-01-21 04:29:35 字数 783 浏览 1 评论 0原文

当FetchDevicEseVent事件触发时，我有follwing集团

class DeviceBloc extends Bloc<DeviceEvent, DeviceState> {
  DataRepository repository;

  DeviceBloc({@required this.repository}) : super(DeviceInitialState()) {
    on<FetchDevicesEvent>(onFetchResources);
  }

  Future<void> onFetchResources(
      FetchDevicesEvent event, Emitter<DeviceState> emit) async {
    emit.call(DeviceLoadingState());

    try {
      List<DeviceResource> devices = await repository.getResources(event.type);
      emit.call(DeviceLoadedState(devices: devices));
    } catch (e) {
      emit.call(DeviceErrorState(message: e.toString()));
    }
  }
}

，如果在运行任务完成之前收到了其他FetchDevicEsevent事件，则会开始长期运行的任务。我该如何暂停已久的任务，并在收到新的Fetchdevicesevent后始终立即开始新的任务？

原文

I have the follwing Bloc

class DeviceBloc extends Bloc<DeviceEvent, DeviceState> {
  DataRepository repository;

  DeviceBloc({@required this.repository}) : super(DeviceInitialState()) {
    on<FetchDevicesEvent>(onFetchResources);
  }

  Future<void> onFetchResources(
      FetchDevicesEvent event, Emitter<DeviceState> emit) async {
    emit.call(DeviceLoadingState());

    try {
      List<DeviceResource> devices = await repository.getResources(event.type);
      emit.call(DeviceLoadedState(devices: devices));
    } catch (e) {
      emit.call(DeviceErrorState(message: e.toString()));
    }
  }
}

When FetchDevicesEvent event is triggered it starts a long running task, if additional FetchDevicesEvent events are recieved before the running task is completed the wrong result are returned to the caller. How can I suspend the awaited task and always start a new as soon as a new FetchDevicesEvent is recieved?

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浅听莫相离 2025-01-28 04:29:35

通过使用transformer：Bloc_concurrency软件包的Restartable（）我自己找到解决方案

class DeviceBloc extends Bloc<DeviceEvent, DeviceState> {
  DataRepository repository;

  DeviceBloc({@required this.repository}) : super(DeviceInitialState()) {
    on<FetchDevicesEvent>(
      onFetchResources,
      transformer: restartable(),
    );
  }

  Future<void> onFetchResources(
      FetchDevicesEvent event, Emitter<DeviceState> emit) async {
    emit.call(DeviceLoadingState());

    try {
      final List<DeviceResource> devices =
          await repository.getResources(event.type);
      emit.call(DeviceLoadedState(devices: devices));
    } catch (e) {
      emit.call(DeviceErrorState(message: e.toString()));
    }
  }

}

Found the solution myself by using transformer: restartable() from bloc_concurrency package

class DeviceBloc extends Bloc<DeviceEvent, DeviceState> {
  DataRepository repository;

  DeviceBloc({@required this.repository}) : super(DeviceInitialState()) {
    on<FetchDevicesEvent>(
      onFetchResources,
      transformer: restartable(),
    );
  }

  Future<void> onFetchResources(
      FetchDevicesEvent event, Emitter<DeviceState> emit) async {
    emit.call(DeviceLoadingState());

    try {
      final List<DeviceResource> devices =
          await repository.getResources(event.type);
      emit.call(DeviceLoadedState(devices: devices));
    } catch (e) {
      emit.call(DeviceErrorState(message: e.toString()));
    }
  }

}

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