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DrawerHeaderのSwitchでダーク/ライトモードを切り替えられるようにしたい。しかし、私はエラーが発生しています。

エラー: このコンシューマ ウィジェットの上に正しいプロバイダが見つかりませんでした これBuildContextは、選択したプロバイダを含まない を使用したために発生する可能性があります。一般的なシナリオがいくつかあります。

  • 読み取ろうとしているプロバイダーは別のルートにあります。プロバイダーは「スコープ」です。そのため、ルート内にプロバイダーを挿入すると、他のルートはそのプロバイダーにアクセスできなくなります。
  • BuildContext読み取ろうとしているプロバイダーの祖先である を使用しました。Consumer が MultiProvider/Provider の下にあることを確認します。これは通常、プロバイダーを作成してすぐに読み取ろうとしたときに発生します。

アナサイファ・ダート

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<ThemeNotifier>(
      create: (_) => ThemeNotifier(),
      child: Consumer<ThemeNotifier>(
        builder: (context, ThemeNotifier notifier, child) {
          return MaterialApp(
            title: 'Flutter Theme Provider',
            theme: notifier.darkTheme ? dark : light,
            home: Anasayfa(),
          );
        },
      ),
    );
  }
}

class Anasayfa extends StatefulWidget {
  @override
  _AnasayfaState createState() => _AnasayfaState();
}

class _AnasayfaState extends State<Anasayfa> {
  int currentPage = 0;

  nested() {
    return NestedScrollView(
        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
          return [
            SliverAppBar(
              toolbarHeight: 40,
              expandedHeight: 92.0,
              floating: false,
              pinned: true,
              flexibleSpace: FlexibleSpaceBar(
                background: Image.asset(
                  "assets/images/besmele.jpg",
                  fit: BoxFit.cover,
                ),
              ),
              actions: [
                IconButton(
                  icon: Icon(Icons.account_circle),
                  color: Colors.white,
                  onPressed: () {},
                ),
              ],
            )
          ];
        },
        body: Container());
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: nested(),
      drawer: Drawer(
        child: DrawerDosyasi(),
      ),
      bottomNavigationBar: CurvedNavigationBar(
        color: Colors.blue,
        backgroundColor: Colors.white,
        buttonBackgroundColor: Colors.blue,
        height: 50,
        items: <Widget>[
          Icon(
            Icons.campaign,
            size: 20,
            color: Colors.white,
          ),
          Icon(
            Icons.supervisor_account,
            size: 20,
            color: Colors.white,
          ),
          Icon(
            Icons.home,
            size: 20,
            color: Colors.white,
          ),
          Icon(
            Icons.video_collection_rounded,
            size: 20,
            color: Colors.white,
          ),
          Icon(
            Icons.menu_book_rounded,
            size: 20,
            color: Colors.white,
          ),
        ],
        animationDuration: Duration(
          milliseconds: 300,
        ),
        index: 2,
        animationCurve: Curves.bounceInOut,
        onTap: (index) {
          debugPrint("Current index is $index");
        },
      ),
    );
  }
}

drawerDosyasi.dart

class DrawerDosyasi extends StatefulWidget {
  @override
  _DrawerDosyasiState createState() => _DrawerDosyasiState();
}

class _DrawerDosyasiState extends State<DrawerDosyasi> {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: ListView(
        padding: EdgeInsets.zero,
        children: <Widget>[
          DrawerHeader(
            decoration: BoxDecoration(
              color: Colors.blue,
            ),
            child: Row(
              children: [
                Expanded(
                  flex: 1,
                  child: Consumer<ThemeNotifier>(
                    builder: (context, notifier, child) => Switch(
                      onChanged: (val) {
                        notifier.toggleTheme();
                      },
                      value: notifier.darkTheme,
                    ),
                  ),
                ),
                Expanded(
                  flex: 3,
                  child: CircleAvatar(
                    radius: 60,
                    backgroundColor: Colors.white,
                  ),
                ),
                Expanded(flex: 1, child: SizedBox.expand()),
              ],
            ),
          ),
          ListTile(
            leading: Icon(Icons.home),
            title: Text('Anasayfa'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.account_circle),
            title: Text('Profil'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.campaign),
            title: Text('Duyurular'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.account_box),
            title: Text('Hocalar'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.library_books),
            title: Text('Dergiler'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.video_collection_rounded),
            title: Text('Canlı Dersler'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.menu_book_rounded),
            title: Text('Kütüphane'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.supervisor_account),
            title: Text('Tartışmalar'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.create),
            title: Text('Yazı Gönder'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.message_rounded),
            title: Text('İletişim'),
            tileColor: Colors.white,
          ),
          ListTile(
            leading: Icon(Icons.exit_to_app_rounded),
            title: Text('Çıkış'),
            tileColor: Colors.white,
          ),
        ],
      ),
    );
  }
}

theme.dart

ThemeData light = ThemeData(
    brightness: Brightness.light,
    primarySwatch: Colors.blue,
    accentColor: Colors.blue,
    scaffoldBackgroundColor: Color(0xfff1f1f1));

ThemeData dark = ThemeData(
  brightness: Brightness.dark,
  primarySwatch: Colors.indigo,
  accentColor: Colors.green[700],
);

class ThemeNotifier extends ChangeNotifier {
  final String key = "theme";
  SharedPreferences _prefs;
  bool _darkTheme;

  bool get darkTheme => _darkTheme;

  ThemeNotifier() {
    _darkTheme = true;
    _loadFromPrefs();
  }

  toggleTheme() {
    _darkTheme = !_darkTheme;
    _saveToPrefs();
    notifyListeners();
  }

pubspec.yaml

name: mto
description: A new Flutter application.

# The following line prevents the package from being accidentally published to
# pub.dev using `pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  firebase_database: ^4.3.0
  page_transition: ^1.1.7+2
  simple_animations: ^2.2.3
  curved_navigation_bar: ^0.3.4
  provider: ^4.3.2+2
  shared_preferences: ^0.5.12+4

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.0

dev_dependencies:
  flutter_test:
    sdk: flutter


# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  assets:
    - assets/images/
  #   - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

アプリケーションは次のようになります

ここに画像の説明を入力

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