Question

我正在使用Bloc模式开发Flutter应用程序。成功认证后，UserSate具有User对象。在所有其他Bloc中，我需要在UserState中访问User对象。我尝试在其他Bloc的构造函数参数上获取UserBloc并访问User对象。但是它表明User对象为null。任何人都有更好的解决方案吗？

class SectorHomeBloc extends Bloc<SectorHomeEvent, SectorHomeState> {
  final OutletRepository outletRepository;
  UserBloc userBloc;
  final ProductRepository productRepository;
  final ProductSubCategoryRepository productSubCategoryRepository;
  final PromotionRepository promotionRepository;
  final ProductMainCategoryRepository mainCategoryRepository;

  SectorHomeBloc({
    @required this.outletRepository,
    @required this.userBloc,
    @required this.productSubCategoryRepository,
    @required this.productRepository,
    @required this.promotionRepository,
    @required this.mainCategoryRepository,
  });
  @override
  SectorHomeState get initialState => SectorHomeLoadingState();

  @override
  Stream<SectorHomeState> mapEventToState(SectorHomeEvent event) async* {
    try {
      print(userBloc.state.toString());
      LatLng _location = LatLng(
          userBloc.state.user.defaultLocation.coordinate.latitude,
          userBloc.state.user.defaultLocation.coordinate.longitude);
      String _token = userBloc.state.user.token;

      if (event is GetAllDataEvent) {
        yield SectorHomeLoadingState();
        List<Outlet> _previousOrderedOutlets =
            await outletRepository.getPreviousOrderedOutlets(
                _token, _location, event.orderType, event.sectorId);

        List<Outlet> _featuredOutlets =
            await outletRepository.getFeaturedOutlets(
                _token, _location, event.orderType, event.sectorId);
        List<Outlet> _nearestOutlets = await outletRepository.getOutletsNearYou(
            _token, _location, event.orderType, event.sectorId);

        List<Product> _newProducts = await productRepository.getNewItems(
            _token, _location, event.orderType, event.sectorId);

        List<Product> _trendingProducts =
            await productRepository.getTrendingItems(
                _token, _location, event.orderType, event.sectorId);

        List<Promotion> _promotions = await promotionRepository
            .getVendorPromotions(_token, event.sectorId);
        yield SectorHomeState(
          previousOrderedOutlets: _previousOrderedOutlets,
          featuredOutlets: _featuredOutlets,
          nearByOutlets: _nearestOutlets,
          newItems: _newProducts,
          trendingItems: _trendingProducts,
          promotions: _promotions,
        );
      }
    } on SocketException {
      yield SectorHomeLoadingErrorState('could not connect to server');
    } catch (e) {
      print(e);
      yield SectorHomeLoadingErrorState('Error');
    }
  }
}

mapEventToState方法中的打印语句[print（userBloc.state.toString（））;]显示UserSate的初始状态。但是，在执行此代码时，UserState位于UserLoggedInState中。

Answer 1

有一种正式的方法可以执行此操作，如文档Bloc-to-Bloc Communication中所述这是文档中的示例

class MyBloc extends Bloc {
  final OtherBloc otherBloc;
  StreamSubscription otherBlocSubscription;

  MyBloc(this.otherBloc) {
    otherBlocSubscription = otherBloc.listen((state) {
        // React to state changes here.
        // Add events here to trigger changes in MyBloc.
    });
  }

  @override
  Future<void> close() {
    otherBlocSubscription.cancel();
    return super.close();
  }
}

如何从另一个集团访问处于集团状态的数据

1 个答案: