升级hydrated_bloc/flutter_bloc遇__storage未初始化LateInitializationError

Error Stack #

DartError: LateInitializationError: Field '__storage' has not been initialized.
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 307:3  throw_
errors.dart:307
packages/hydrated_bloc/src/hydrated_bloc.dart 107:22                         get [__storage]
hydrated_bloc.dart:107
packages/hydrated_bloc/src/hydrated_bloc.dart 154:19                         onChange
hydrated_bloc.dart:154
packages/bloc/src/bloc_base.dart 103:7                                       emit
bloc_base.dart:103

My Code #

initServices function #

Future<void> initServices({String? env}) async {
  WidgetsFlutterBinding.ensureInitialized();
  HydratedBloc.storage = await HydratedStorage.build(
    storageDirectory: kIsWeb
        ? HydratedStorageDirectory.web
        : HydratedStorageDirectory((await getTemporaryDirectory()).path),
  );

  final from = getParams();
  await EnvCubit.instance.init(from.fromBrand, env: env);
}

main function #

void main() async {
  await initServices(env: 'dev');
  runApp(const MyApp());
}

Solution #

hydrated_bloc 10移除了直接赋值HydratedBloc.storage的支持，必须通过HydratedBloc.initialize或HydratedBlocOverrides.runZoned方法，在所有HydratedBloc/Cubit实例创建前完成存储初始化。

Option 1: 使用HydratedBloc.initialize #

修改initServices和main函数如下：

Future<void> initServices({String? env}) async {
  WidgetsFlutterBinding.ensureInitialized();
  
  // 使用HydratedBloc.initialize初始化存储
  await HydratedBloc.initialize(
    storage: () async => HydratedStorage.build(
      storageDirectory: kIsWeb
          ? HydratedStorageDirectory.web
          : HydratedStorageDirectory((await getTemporaryDirectory()).path),
    ),
  );

  final from = getParams();
  await EnvCubit.instance.init(from.fromBrand, env: env);
}

void main() async {
  await initServices(env: 'dev');
  runApp(const MyApp());
}

Option 2: 用HydratedBlocOverrides.runZoned包裹初始化逻辑 #

如果希望将存储初始化封装在zone内：

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  
  final storage = await HydratedStorage.build(
    storageDirectory: kIsWeb
        ? HydratedStorageDirectory.web
        : HydratedStorageDirectory((await getTemporaryDirectory()).path),
  );

  await HydratedBlocOverrides.runZoned(
    () async {
      final from = getParams();
      await EnvCubit.instance.init(from.fromBrand, env: 'dev');
      runApp(const MyApp());
    },
    storage: storage,
  );
}

原因说明 #

hydrated_bloc 10中不再允许直接赋值静态字段HydratedBloc.storage，新的初始化方法能确保存储实例在所有HydratedBloc/Cubit尝试访问前完成设置，从而避免出现你遇到的LateInitializationError。

内容的提问来源于stack exchange，提问作者Alin1233