使用Flutter和BloC更新切换按钮

Question

我正在使用youtube api并放置一个“收藏夹”切换按钮，以根据状态填充和清空图标，并将其保存在名为“收藏夹”的新页面的ListView中。在新页面中，一切正常，因为我可以看到最喜欢的图标已填充，但在当前视图中并未实时刷新/更新。如果我切换到statefulWidget，则可以使用“ setstate”使其工作，但是如果我从“收藏夹”页面中清空图标，则更改不会反映出来。

我的方法一定有问题，因为我应该使用Bloc状态来同时更改这两个状态，但实际上卡在了这里。请您看看我的代码并给我一些想法或想法吗？

Bloc文件

class MasterBloc extends Bloc<MasterEvents, MasterState> {
  @override
  MasterState get initialState => MasterState.initialState();

  @override
  Stream<MasterState> mapEventToState(MasterEvents event) async* {
    if (event is MasterSetTab) {
      yield this.state.copyWith(currentTab: event.tab);
    } else if (event is MasterAddToHistory) {
      yield* _addToHistory(event);
    } else if (event is MasterRemoveFromHistory) {
      yield* _removeFromHistory(event);
    } else if (event is MasterToggleInFavorites) {
      yield* _toggleInFavorites(event);
    } else if (event is MasterLogout) {
      yield this.state.copyWith(history: [], currentTab: 0);
    }
  }

  Stream<MasterState> _addToHistory(MasterAddToHistory event) async* {
    final int index = this
        .state
        .history
        .indexWhere((item) => item.videoId == event.youtubeVideo.videoId);

    if (index == -1) {
      final history = List<YoutubeVideo>.from(this.state.history);
      history.add(event.youtubeVideo);

      yield this.state.copyWith(history: history);
    }
  }

  Stream<MasterState> _removeFromHistory(MasterRemoveFromHistory event) async* {
    final history = List<YoutubeVideo>.from(this.state.history);
    history.removeAt(event.index);
    yield this.state.copyWith(history: history);
  }

  Stream<MasterState> _toggleInFavorites(MasterToggleInFavorites event) async* {
    final int index = this
        .state
        .favorites
        .indexWhere((item) => item.videoId == event.youtubeVideo.videoId);

    if (index == -1) {
      final favorites = List<YoutubeVideo>.from(this.state.favorites);
      favorites.add(event.youtubeVideo);
      event.youtubeVideo.isFavorite = true;

      yield this.state.copyWith(favorites: favorites);
    } else {
      final favorites = List<YoutubeVideo>.from(this.state.favorites);
      favorites.removeAt(index);
      event.youtubeVideo.isFavorite = false;

      yield this.state.copyWith(favorites: favorites);
    }
  }
}

集团状态

class MasterState extends Equatable {
  final int currentTab;
  final List<YoutubeVideo> history;
  final List<YoutubeVideo> favorites;

  MasterState(
      {@required this.currentTab, @required this.history, this.favorites});

  static MasterState initialState() =>
      MasterState(currentTab: 0, history: [], favorites: []);

  MasterState copyWith(
      {int currentTab,
      List<YoutubeVideo> history,
      List<YoutubeVideo> favorites}) {
    return MasterState(
        currentTab: currentTab ?? this.currentTab,
        history: history ?? this.history,
        favorites: favorites ?? this.favorites);
  }

  @override
  List<Object> get props => [currentTab, history, favorites];
}

BloC活动

import 'package:documentales_app/models/youtube_video.dart';

abstract class MasterEvents {}

class MasterSetTab extends MasterEvents {
  final int tab;

  MasterSetTab(this.tab);
}

class MasterAddToHistory extends MasterEvents {
  final YoutubeVideo youtubeVideo;

  MasterAddToHistory(this.youtubeVideo);
}

class MasterRemoveFromHistory extends MasterEvents {
  final int index;

  MasterRemoveFromHistory(this.index);
}

class MasterToggleInFavorites extends MasterEvents {
  final YoutubeVideo youtubeVideo;

  MasterToggleInFavorites(this.youtubeVideo);
}

class MasterLogout extends MasterEvents {}

“收藏夹”标签

class FavsTab extends StatefulWidget {
  @override
  _FavsTabState createState() => _FavsTabState();
}

class _FavsTabState extends State<FavsTab> {
  @override
  Widget build(BuildContext context) {
    final bloc = BlocProvider.of<MasterBloc>(context);
    return BlocBuilder<MasterBloc, MasterState>(
      builder: (_, state) {
        if (state.favorites.length == 0) {
          return Center(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                SvgPicture.asset('assets/icons/empty.svg',
                    width: 50, color: Colors.greenAccent),
                SizedBox(
                  height: 5,
                ),
                Text(
                  'No hay favoritos ..',
                  style: TextStyle(
                      color: Colors.greenAccent,
                      fontWeight: FontWeight.bold,
                      fontSize: 20),
                )
              ],
            ),
          );
        }
        return ListView.builder(
          itemBuilder: (_, index) {
            final YoutubeVideo item = state.favorites[index];
            return YoutubeVideoItem(
              item: item,
              onDismissed: () {
                bloc.add(MasterToggleInFavorites(item));
              },
            );
          },
          itemCount: state.favorites.length,
        );
      },
      condition: (prevState, newState) =>
          prevState.favorites.length != newState.favorites.length,
    );
  }
}

称为状态的首页标签

class HomeTab extends StatefulWidget {
  @override
  _HomeTabState createState() => _HomeTabState();
}

class _HomeTabState extends State<HomeTab> {
  AccountApi _accountApi = AccountApi();
  YoutubeApi _youtubeApi = YoutubeApi(apiKey: API_KEY);
  List<dynamic> _users = [];
  List<PlayList> _playlists = [];
  List<YoutubeVideo> _newVideos = [];
  bool _isLoading = true;

  @override
  void initState() {
    super.initState();
    _load();
  }

  _load() async {
    final users = await _accountApi.getUsers(1);
    final List<PlayList> playLists =
        await _youtubeApi.getPlaylists('UCCMksip5JfLMW4AJGsjTYUA');
    final List<YoutubeVideo> newVideos = await _youtubeApi
        .getPlaylistVideos('PLFXLg_sVKmuujWVeOmrzsM1NnDFa8uoNk');
    setState(() {
      _users.addAll(users);
      _playlists.addAll(playLists);
      _newVideos.addAll(newVideos);
      _isLoading = false;
    });
  }

  @override
  Widget build(BuildContext context) {
    return ListView(
      children: [
        _isLoading
            ? HomeTabShimmer()
            : Column(
                children: [
                  TopPlayLists(items: _playlists),
                  SizedBox(height: 10),
                  NewVideos(
                    items: _newVideos,
                  ),
                  SizedBox(height: 5),
                ],
              )
      ],
    );
  }
}

最后切换按钮

CupertinoButton(
                        padding: EdgeInsets.zero,
                        minSize: 30,
                        onPressed: () {
                          masterBloc.add(MasterToggleInFavorites(item));
                        },
                        child: CircleContainer(
                          child: Icon(
                            //Icons.playlist_add,
                            item.isFavorite
                                ? Icons.favorite
                                : Icons.favorite_border,
                            color: Colors.white,
                          ),
                          size: 35,
                        ),
                      ),