问题状态未在Flutter Bloc中更新

分类：编程问答

如何解决问题状态未在Flutter Bloc中更新

我正在使用Bloc软件包来更新Flutter应用上的窗口小部件。我尝试更新一个变量，它是收藏夹列表。为此，我要获取状态并将其修改为新值，然后产生新的one（state）。结果是无法在当前页面中看到反映的更改，但正在克隆状态下工作（因为它已正确加载到新选项卡中）。我做错了什么，因为我看不到当前状态中反映的更改，但能够在克隆中完成更改？如果有不清楚的地方，请告诉我，否则我应该从我的代码库中分享其他内容。

更新1：如果我手动进行热重装，我可以看到更改，但是我想自动完成。

主州

import 'package:meta/meta.dart' show required;
import 'package:documentales_app/models/youtube_video.dart';
import 'package:equatable/equatable.dart';

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];
}

大师BLOC 

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);
    }
  }

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,

“收藏夹”标签

import 'package:cached_network_image/cached_network_image.dart';
import 'package:documentales_app/blocs/pages/master_bloc/master_bloc.dart';
import 'package:documentales_app/blocs/pages/master_bloc/master_events.dart';
import 'package:documentales_app/models/youtube_video.dart';
import 'package:share/share.dart';
import 'package:documentales_app/widgets/circle_container.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_youtube/flutter_youtube.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import '../utils/keys.dart';

class YoutubeVideoItem extends StatelessWidget {
  final VoidCallback onDismissed;
  final YoutubeVideo item;

  const YoutubeVideoItem({@required this.item,this.onDismissed})
      : assert(item != null);

  Widget _getView(MasterBloc masterBloc) {
    return Container(
      child: CupertinoButton(
        padding: EdgeInsets.zero,onPressed: () {
          masterBloc.add(MasterAddToHistory(item));
          FlutterYoutube.playYoutubeVideoByUrl(
              apiKey: API_KEY,videoUrl: "https://www.youtube.com/watch?v=${item.videoId}",autoPlay: true,//default falase
              fullScreen: true //default false
              );
        },child: AspectRatio(
          aspectRatio: 12 / 3,child: Container(
            margin: EdgeInsets.symmetric(vertical: 5,horizontal: 10),padding: EdgeInsets.all(5),decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(10),color: Colors.greenAccent,boxShadow: [
                BoxShadow(color: Colors.black26,blurRadius: 5),],child: Row(
              children: [
                Expanded(
                  flex: 4,child: ClipRRect(
                    borderRadius: BorderRadius.circular(10),child: CachedNetworkImage(
                      imageUrl: item.banner,fit: BoxFit.cover,height: double.infinity,Expanded(
                  flex: 5,child: Container(
                    padding: EdgeInsets.all(10),child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,children: [
                        Text(
                          item.title,maxLines: 2,style: TextStyle(
                              fontWeight: FontWeight.w500,fontSize: 14),SizedBox(
                          height: 5,Expanded(
                          child: Text(
                            item.description,overflow: TextOverflow.fade,style: TextStyle(
                                fontWeight: FontWeight.w300,color: Colors.grey[600],fontSize: 13),Expanded(
                  flex: 1,child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,children: [
                      CupertinoButton(
                        padding: EdgeInsets.zero,CupertinoButton(
                        padding: EdgeInsets.zero,onPressed: () {
                          Share.share(
                              'https://www.youtube.com/watch?v=${item.videoId}',subject: 'Mira este impresionante documental');
                        },child: CircleContainer(
                          child: Icon(
                            Icons.share,);
  }

  @override
  Widget build(BuildContext context) {
    final masterBloc = BlocProvider.of<MasterBloc>(context);

    if (onDismissed != null) {
      return Dismissible(
        key: Key(item.videoId),onDismissed: (_) {
          if (onDismissed != null) {
            onDismissed();
          }
        },child: _getView(masterBloc),);
    }
    return _getView(masterBloc);
  }
}

主页标签

import 'package:cached_network_image/cached_network_image.dart';
import 'package:documentales_app/api/account_api.dart';
import 'package:documentales_app/api/youtube_api.dart';
import 'package:documentales_app/models/play_list.dart';
import 'package:documentales_app/models/youtube_video.dart';
import 'package:documentales_app/pages/home_page_widgets/home_tab_shimmer.dart';
import 'package:documentales_app/pages/home_page_widgets/new_videos.dart';
import 'package:documentales_app/pages/home_page_widgets/top_play_lists.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import '../../utils/keys.dart';

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('jklnvfyyklhjh');
    final List<YoutubeVideo> newVideos = await _youtubeApi
        .getPlaylistVideos('PLFXLg_sbbjkGKJbkjgkkGKkgk');
    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),)
      ],);
  }
}

解决方法

只有一种状态吗？
我知道状态不会更改为同名状态。

如果要使用当前结构（如代码）。
在状态更改之间，您需要一个状态，例如“ MasterStateChanging”。

loadCloudWatchLogs(nextToken?: string) {
  // Set the region
  AWS.config.update({
    region: 'sa-east-1',credentials: {
      accessKeyId: environment.awsAccessKeyId,secretAccessKey: environment.awsSecretAccessKey,},});

  // Create the CloudWatchLogs service object
  const cloudwatchlogs = new AWS.CloudWatchLogs({ apiVersion: '2014-03-28' });

  // Defines the params attributes pattern.
  let params: AWSCloudWatchParams;

  // Check if token was provided to permorm a next query to AWSCloudWatchLogs.
  if (nextToken) {
    params = {
      logGroupName: 'group-name' /* required */,startTime: this.startTime,endTime: this.endTime,logStreamNamePrefix: this.device,filterPattern: `{ ($.device="${this.device}") }`,nextToken,};
  } else {
    params = {
      logGroupName: 'group-name' /* required */,};
  }

  // Execute a filter for logs.
  cloudwatchlogs.filterLogEvents(params,(err,data) => {
    if (err) {
      console.log(err,err.stack);
    } else {
      if (data.searchedLogStreams.length > 0) {
        // Chegk if exists more logs for query.
        const loadMoreLogs = !data.searchedLogStreams[
          data.searchedLogStreams.length - 1
        ].searchedCompletely;

        // Update the token for the next query.
        this.nextToken = data.nextToken;

        data.events.forEach(log => {
          // log proccessing...
        });
      }
    }
  });
}

<State File>
class MasterStateChanging extends Equatable {
  
}

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