flutter - 在此RestoreLocalBackupPage小部件上方找不到正确的Provider <HomeBloc>，如何以比我更简单的方式解决此问题？

我正在尝试构建具有备份和还原功能的Notes应用程序。我有一个打开应用程序时显示的主页。该页面的主体是一个脚手架，该脚手架又具有一个带有ListTiles的抽屉，用于备份和还原。我使用HomeBloc对象与保存注释的数据库进行交互，因此我使用Provider可以在任何地方访问它。

ListTiles打开MaterialPageRoute进入新屏幕，在该屏幕中，提示用户选择文件，输入密码等。

当我点击抽屉中的Restore ListTile时，出现此错误:

The following ProviderNotFoundException was thrown building RestoreLocalBackupPage(dirty, state: _RestoreLocalBackupPageState#4f937):
Error: Could not find the correct Provider<HomeBloc> above this RestoreLocalBackupPage Widget

This likely happens because you used a `BuildContext` that does not include the provider
of your choice.

这是我的main.dart，我将主页包装在提供程序中:

void main() {
  runApp(
      MyApp()
  );
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Notes',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: Provider(
        create: (_) => HomeBloc(),
        child: HomePage(),
      )
    );
  }
}

这是我的主页的构建方法:

Widget build(BuildContext context) {
    homeBloc = Provider.of<HomeBloc>(context);
    return Scaffold(
      backgroundColor: Color.fromRGBO(219, 243, 250, 1),
      appBar: AppBar(...),
      body: StreamBuilder<List<Note>>(...),
      floatingActionButton: FloatingActionButton(...),
      drawer: HomeDrawer(),
    );
  }

HomeDrawer的build方法返回一个Drawer，该子项具有一个ListView作为其子级。这是启动“还原备份”页面的ListTile的代码:

ListTile(
        title: Text('Local Backup',
            style: GoogleFonts.sourceSansPro(
                textStyle: TextStyle(fontWeight: FontWeight.w500),
                fontSize: 16)),
        onTap: () async {
          // Update the state of the app
          // ...
          // Then close the drawer
          bool permissionGranted = await _getPermissions(context);
          if (permissionGranted) {
               Navigator.of(context).push(
                MaterialPageRoute(
                  builder: (context) => CreateLocalBackupPage(
                  currentBackupDirectory: currentBackupDirectory
                  ),
                )
            );
          }
        },
      )

这是我点击上面的ListTile时遇到的错误:

The following ProviderNotFoundException was thrown building RestoreLocalBackupPage(dirty, state: _RestoreLocalBackupPageState#4f937):
Error: Could not find the correct Provider<HomeBloc> above this RestoreLocalBackupPage Widget

This likely happens because you used a `BuildContext` that does not include the provider
of your choice.

HomeDrawer()的BuildContext确实可以访问我需要的HomeBloc对象。因此，将RestoreLocalBackupPage小部件包装在另一个Provider中是可行的:

HomeBloc homebloc = Provider.of<HomeBloc>(context);
Navigator.of(context).push(
    MaterialPageRoute(
        builder: (context) => Provider(
            create: (_) => homebloc,
            child: RestoreLocalBackupPage(currentBackupDirectory: currentBackupDirectory),
        )
    )
);

我想知道是否存在使用提供程序在RestoreLocalBackupPage内部访问HomeBloc的更简单，更优雅的方法。通过构造函数进行的依赖注入(inject)是可行的，但这种方法首先破坏了使用Provider的目的，对吗？

最佳答案

用提供程序包装main.dart中的MaterialApp解决了我的问题。 I have found the solution here. Check rrousselGit's answer.

之后，main.dart现在变为:

void main() {
  runApp(
      MyApp()
  );
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    LicenseRegistry.addLicense(() async* {
      final license = await rootBundle.loadString('google_fonts/Cabin_OFL.txt');
      yield LicenseEntryWithLineBreaks(['google_fonts_Cabin'], license);
    });
    LicenseRegistry.addLicense(() async* {
      final license = await rootBundle.loadString('google_fonts/SSP_OFL.txt');
      yield LicenseEntryWithLineBreaks(['google_fonts_SSP'], license);
    });
    return Provider(
      create: (_) => HomeBloc(),
      child: MaterialApp(
          title: 'Notes',
          theme: ThemeData(
            primarySwatch: Colors.blue,
            visualDensity: VisualDensity.adaptivePlatformDensity,
          ),
          home: HomePage(),
      ),
    );
  }
}

关于flutter - 在此RestoreLocalBackupPage小部件上方找不到正确的Provider <HomeBloc>，如何以比我更简单的方式解决此问题？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/62349890/