GetX - Sample Translation with GetStorage, GetxService, DropDownButton and PopMenuButton

main.dart

import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:get_storage/get_storage.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await initialConfig();

  final storage = Get.find<StorageService>();

  runApp(GetMaterialApp(
    debugShowCheckedModeBanner: false,
    translations: AppTranslations(),
    // Get.deviceLocale with problem in iOS
    // Not return countryCode, only return languageCode
    // On the first load of the Application
    // (flutter problem, not GetX)
    locale: storage.languageCode != null
        ? Locale(storage.languageCode, storage.countryCode)
        : Locale('pt', 'BR'), // Not Get.deviceLocale
    fallbackLocale: Locale('en', 'US'),
    initialRoute: '/home',
    getPages: [GetPage(name: '/home', page: () => Home())],
    initialBinding: InitialBinding(),
  ));
}

Future<void> initialConfig() async {
  await Get.putAsync(() => StorageService().init());
  // DBService, ...
}

class StorageService extends GetxService {
  String languageCode;
  String countryCode;

  Future<StorageService> init() async {
    await GetStorage.init();
    languageCode = await GetStorage().read('languageCode');
    countryCode = await GetStorage().read('countryCode');
    return this;
  }

  void write(String key, dynamic value) {
    GetStorage().write(key, value);
  }
}

class Home extends StatelessWidget {
  @override
  Widget build(context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("${'hello'.tr}"),
        actions: [LanguageMenu()],
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Center(child: Text("${'welcome'.tr}")),
          SizedBox(height: 32),
          LanguageDropDown(),
        ],
      ),
    );
  }
}

class InitialBinding implements Bindings {
  @override
  void dependencies() {
    Get.put(LanguageController(), permanent: true);
  }
}

class LanguageController extends GetxController {
  final storage = Get.find<StorageService>();
  final RxString locale = Get.locale.toString().obs;

  final Map<String, dynamic> optionsLocales = {
    'en_US': {
      'languageCode': 'en',
      'countryCode': 'US',
      'description': 'English'
    },
    'de_DE': {
      'languageCode': 'de',
      'countryCode': 'DE',
      'description': 'German'
    },
    'pt_BR': {
      'languageCode': 'pt',
      'countryCode': 'BR',
      'description': 'Português'
    },
  };

  void updateLocale(String key) {
    final String languageCode = optionsLocales[key]['languageCode'];
    final String countryCode = optionsLocales[key]['countryCode'];
    // Update App
    Get.updateLocale(Locale(languageCode, countryCode));
    // Update obs
    locale.value = Get.locale.toString();
    // Update storage
    storage.write('languageCode', languageCode);
    storage.write('countryCode', countryCode);
  }
}

class LanguageDropDown extends GetView<LanguageController> {
  @override
  Widget build(BuildContext context) {
    return Obx(
      () => DropdownButton<String>(
        value: controller.locale.value,
        icon: Icon(Icons.arrow_downward),
        iconSize: 24,
        elevation: 16,
        style: TextStyle(color: Colors.deepPurple),
        underline: Container(
          height: 2,
          color: Colors.deepPurpleAccent,
        ),
        onChanged: (String newValue) {
          controller.updateLocale(newValue);
        },
        items: controller.optionsLocales.entries.map((item) {
          return DropdownMenuItem<String>(
            value: item.key,
            child: Text(item.value['description']),
          );
        }).toList(),
      ),
    );
  }
}

class LanguageMenu extends GetView<LanguageController> {
  @override
  Widget build(BuildContext context) {
    return PopupMenuButton(
      icon: Icon(Icons.language),
      offset: Offset(0, 30),
      itemBuilder: (context) => controller.optionsLocales.entries.map((item) {
        return PopupMenuItem(
          value: item.key,
          child: Text(item.value['description']),
        );
      }).toList(),
      onSelected: (newValue) {
        controller.updateLocale(newValue);
      },
    );
  }
}

class AppTranslations extends Translations {
  @override
  Map<String, Map<String, String>> get keys => {
        'en_US': {
          'hello': 'Hello World',
          'welcome': 'Welcome',
        },
        'de_DE': {
          'hello': 'Hallo Welt',
          'welcome': 'willkommen',
        },
        'pt_BR': {
          'hello': 'Alo Mundo',
          'welcome': 'Bem-vindo',
        },
      };
}

I got a error in storage service languageCode and countryCode always return a null i fix it like this
languageCode = await GetStorage().read('languageCode') ?? 'en';
countryCode = await GetStorage().read('countryCode') ?? 'US';
but i think it's wrong

and error in LanguageDropDown onChange i fix it like this
onChanged: (String? newValue) {
controller.updateLocale(newValue!);
}
if this is a better solution let me know