在Flutter Hive中添加元素时出现问题

如何解决在Flutter Hive中添加元素时出现问题

第一次在Flutter中使用Hive时遇到一些问题。在此之前，我使用的是Sqflite，并且一切都按预期执行，但是我切换到Hive，以提高性能，而切换到Hive。 问题是，当我用数据初始化两个Hive框“ AvatarsPack”和“ AvatarItem”时，甚至等待DB上的每次插入，看起来Hive都会在完成所有插入之前返回，因此，我的FutureBuilder生成时没有获取值。我试图解决这个问题大约3天，然后我几乎切换回Sqflite，但是我记得这里有很棒的家伙可以在几秒钟内解决这个问题，所以这就是我在做的，我在问大家的帮助。感谢您的阅读，直到这里，下面是代码：

avatars_view.dart

  final _controller = AvatarsController();

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
        future: _controller.initializeRepository(),builder: (context,snapshot) {
          Future.delayed(Duration(seconds: 1)).then((value) => print(_controller.getAvatarsPacks()[9].avatars));

          if (snapshot.connectionState == ConnectionState.done) {
            print('@@@@@${_controller.getAvatarsPacks()[0].avatars}');
            return MyShop(
              getOwnedItems: _controller.getOwnedAvatars,ownedTabTile: 'Owned',isScrollable: true,headers: _controller.getHeaders(),bodies:
                  _controller.getAvatarsPacks().map((e) => e.avatars).toList(),);
          }

          return Container();
        });
  }
}

avatars_controller.dart

  final _repository = AvatarsRepository();

  final Map<String,int> _AVATARS_PACKS_AMOUNT = {
    'superheroes': 50,'children': 30,'halloween-1': 50,'halloween-2': 50,'halloween-3': 50,'hospital': 18,'people-1': 50,'people-2': 50,'people-3': 18,'professions': 50,};

  List<AvatarsPack> getAvatarsPacks() {
    return _repository.getAllAvatarsPacks();
  }

  Future<void> initializeRepository() async {
    await _repository
        .openBoxes()
        .then((value) => print('----Boxes are oppened'));
    await _clearBoxes().then((value) => print('----Boxes were cleared'));
    if (_repository.isEmpty()) {
      print('----boxes are empty');
      await _initializeRepositoryData().then((value) =>
          print('avatars quantity: ${_repository.getQuantityAvatarItems()}'));
    }

    return;
  }

  List<String> getHeaders() {
    return _AVATARS_PACKS_AMOUNT.keys.toList();
  }

  List<AvatarItem> getOwnedAvatars() {
    return _repository.getOwnedAvatars();
  }

  void updateAvatarItem(AvatarItem avatarItem) =>
      _repository.updateAvatarItem(avatarItem);

  Future<void> _initializeRepositoryData() async {
    print('*******_initializeRepositoryData called()');
    return _AVATARS_PACKS_AMOUNT.forEach((key,quantity) async {
      final avatarsPack = AvatarsPack.create(
          packID: key,quantity: quantity,packItemPrice: Money.all(coins: 50,diamonds: 5));
      await _repository.addPack(avatarsPack);
    });
  }

  Future<void> _clearBoxes() {
    return _repository.clearBoxes();
  }

  @override
  FutureOr onClose() {
    _repository.closeBoxes();
    super.onClose();
  }
}

avatars_repository.dart

  Box _avatarsPackBox;
  Box _avatarItemBox;

  final AVATAR_PACK = 'avatarsPack';
  final AVATAR_ITEM = 'avatarItem';

  Box get _avatarsPackInstance {
    return _avatarsPackBox ??= Hive.box(AVATAR_PACK);
  }

  Box get _avatarItemInstance {
    return _avatarItemBox ??= Hive.box(AVATAR_ITEM);
  }

  Future<void> addPack(AvatarsPack avatarsPack) async {
    await _avatarsPackInstance.add(avatarsPack.toJson());

    return avatarsPack.avatars.forEach((element) async {
      await _avatarItemInstance.add(element.toJson());
    });
  }

  List<AvatarsPack> getAllAvatarsPacks() {
    final avatarsPacks = _avatarsPackInstance.values
        .map((json) => AvatarsPack.fromJson(json))
        .toList();

    avatarsPacks.forEach((avatarPack) {
      avatarPack.avatars = getAvatarItemsFromPack(avatarPack.packID);
    });

    return avatarsPacks;
  }

  Future<void> addAvatarItem(AvatarItem avatarItem) async {
    await _avatarItemInstance.add(avatarItem.toJson());
    return;
  }

  Future<void> updateAvatarItem(AvatarItem avatarItem) {
    final index =
        getAllAvatarItems().indexWhere((e) => e.pack == avatarItem.pack);
    return _avatarItemInstance.putAt(index,avatarItem.toJson());
  }

  List<AvatarItem> getAllAvatarItems() {
    return _avatarItemInstance.values
        .map((json) => AvatarItem.fromJson(json))
        .toList();
  }

  int getQuantityAvatarItems() {
    return _avatarItemInstance.values.length;
  }

  List<AvatarItem> getAvatarItemsFromPack(String packID) {
    final List<AvatarItem> avatars = [];
    getAllAvatarItems().forEach((avatarItem) {
      if (avatarItem.pack == packID) avatars.add(avatarItem);
    });
    return avatars;
  }

  List<AvatarItem> getOwnedAvatars() {
    return getAllAvatarItems().where((element) =>
        element.isOwned()).toList();
  }

  Future<void> openBoxes() async {
    await Hive.openBox(AVATAR_PACK);
    await Hive.openBox(AVATAR_ITEM);
    return;
  }

  Future<void> closeBoxes() async {
    await _avatarsPackInstance.close();
    await _avatarItemInstance.close();
    return;
  }

  Future<void> clearBoxes() async {
    await _avatarsPackInstance.clear();
    await _avatarItemInstance.clear();
    return;
  }

  bool isEmpty() {
    return _avatarsPackInstance.isEmpty;
  }
}

关于我的头像图像，它们位于名称与它们的packID相同的文件夹中，并且每个文件夹包含以这种方式命名的X个元素img-0，img-2，...，img- [x-1]， img-x。任何反馈将不胜感激，谢谢：）

解决方法

尝试使用 ValueListenableBuilder() 而不是 FutureBuilder()。 这会观察 Box 上的变化并相应地反映这些变化。

import 'package:hive_flutter/hive_flutter.dart';


ValueListenableBuilder(
          valueListenable:
              Hive.box(YOURBOX).listenable(),builder: (context,Box box,_) {
            return SomeWidget(withSomeData);
          },