Flutter Getx - "Xxx" 未找到。您需要调用 "Get.put(Xxx())" - 但我调用了 Get.put(Xxx())

Question

我有这个全局绑定 class 来初始化一些服务，我需要立即初始化它：

import 'package:get/get.dart';
import 'package:vepo/data/data_provider/local_data_provider.dart';
import 'package:vepo/data/data_source/local_data_source.dart';

import 'services/authentication_service.dart';

class GlobalBindings extends Bindings {
  final LocalDataProvider _localDataProvider = LocalDataProvider();
  @override
  void dependencies() {
    Get.put<AuthenticationService>(AuthenticationService(), permanent: true);
    Get.put<LocalDataProvider>(_localDataProvider, permanent: true);
    Get.put<LocalDataSource>(LocalDataSource(_localDataProvider),
        permanent: true);
  }
}

在我的 initialBindings 中：

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      title: 'Vepo',
      initialRoute: AppPages.INITIAL,
      initialBinding: GlobalBindings(),
      transitionDuration: const Duration(milliseconds: 500),
      defaultTransition: Transition.rightToLeft,
      getPages: AppPages.routes,
      home: Root(),
      theme: homeTheme,
    );
  }
}

然后在 class 构造函数中我尝试“找到”它：

class UserLocalRepository extends VpService implements IUserLocalRepository {
  UserLocalRepository() {
    localDataSource = Get.find<LocalDataSource>();
  }

  LocalDataSource localDataSource;

并得到这个错误：

══════ Exception caught by widgets library ═══════════════════════════════════
The following message was thrown building App(dirty):
"LocalDataSource" not found. You need to call "Get.put(LocalDataSource())" or "Get.lazyPut(()=>LocalDataSource())"

The relevant error-causing widget was
App
lib/main.dart:17
When the exception was thrown, this was the stack
#0      GetInstance.find
package:get/…/src/get_instance.dart:272
#1      Inst.find
package:get/…/src/extension_instance.dart:66
#2      new UserLocalRepository
package:vepo/…/user/user_local_repository.dart:10
#3      new LoggedOutNickNameBinding
package:vepo/…/logged_out_nickname/logged_out_nick_name_binding.dart:11
#4      AppPages.routes
package:vepo/…/routes/app_pages.dart:29
...
════════════════════════════════════════════════════════════════════════════════

这是错误消息中提到的绑定：

class LoggedOutNickNameBinding extends Bindings {
  LoggedOutNickNameBinding() {
    _repository = Get.put(UserLocalRepository());
  }

  IUserLocalRepository _repository;

  @override
  void dependencies() {
    Get.lazyPut<LoggedOutNickNameController>(
      () => LoggedOutNickNameController(_repository),
    );
  }
}

为什么“initialBindings”没有初始化，以便我的应用程序可以在应用程序启动时“找到”它们？

Answer 1

我猜你的 GlobalBindings.dependencies() 方法被调用的时间和你需要这些资源的时间不匹配。

您可以尝试初始化您的绑定 class 先于到 GetMaterialApp，而不是将您的绑定 class 传递给 GetMaterialApp.

void main() async {
  //WidgetsFlutterBinding.ensureInitialized(); // uncomment if needed for resource initialization
  GlobalBindings().dependencies();
  runApp(MyApp());
}

切线

这里只是猜测，但是您通过 Get.put 初始化的某些 class 是否在准备好使用之前启动缓慢（即异步）？

如果是这样你可以使用

Get.putAsync<YourClass>(() async {
 // init YourClass here
 return await YourClass.slowInit();

}

例子

我最近运行在为用户交互加载应用程序之前执行异步绑定初始化的练习。这是代码：

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

enum Version {
  lazy,
  wait
}
// Cmd-line args/Env vars: 
const String version = String.fromEnvironment('VERSION');
const Version running = version == "lazy" ? Version.lazy : Version.wait;

void main() async {
  //WidgetsFlutterBinding.ensureInitialized(); // if needed for resources
  if (running == Version.lazy) {
    print('running LAZY version');
    LazyBindings().dependencies();
  }

  if (running == Version.wait) {
    print('running AWAIT version');
    await AwaitBindings().dependencies(); // await is key here
  }

  runApp(MyApp());
}

class LazyBindings extends Bindings {
  @override
  void dependencies() {
    Get.lazyPut<MyDbController>(() => MyDbController());
  }
}

/// Simulates a slow (2 sec.) init of a data access object.
/// Calling [await] dependencies(), your app will wait until dependencies are loaded.
class AwaitBindings extends Bindings {
  @override
  Future<void> dependencies() async {
    await Get.putAsync<MyDbController>(() async {
      Dao _dao = await Dao.createAsync();
      return MyDbController(myDao: _dao);
    });
  }
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  final MyDbController dbc = Get.find();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('GetX Bindings'),
      ),
      body: Center(
        child: Obx(() => Text(dbc.dbItem.value)),
      ),
    );
  }
}

class MyDbController extends GetxController {
  Dao myDao;

  MyDbController({this.myDao});

  RxString dbItem = 'Awaiting data'.obs;

  @override
  void onInit() {
    super.onInit();
    initDao();
  }

  Future<void> initDao() async {
    // instantiate Dao only if null (i.e. not supplied in constructor)
    myDao ??= await Dao.createAsync();
    dbItem.value = myDao.dbValue;
  }
}

class Dao {
  String dbValue;

  Dao._privateConstructor();

  static Future<Dao> createAsync() async {
    var dao = Dao._privateConstructor();
    print('Dao.createAsync() called');
    return dao._initAsync();
  }

  /// Simulates a long-loading process such as remote DB connection or device
  /// file storage access.
  Future<Dao> _initAsync() async {
    dbValue = await Future.delayed(Duration(seconds: 2), () => 'Some DB data');
    print('Dao._initAsync done');
    return this;
  }
}

Answer 2

以我为例:::

TestCartController? cartController;

if(condition){
 cartController = Get.isRegistered<TestCartController>()
            ? Get.find<TestCartController>()
            : Get.put(TestCartController());

}

但在其他一些小部件中，我将上述控制器称为

final cartController = Get.find<TestCartController>();

类型不匹配问题，因为两个实例都不同，所以这给我造成了问题。我只是删除了那个？马克，它奏效了。

TestCartController cartController;

if(condition){
 cartController = Get.isRegistered<TestCartController>()
            ? Get.find<TestCartController>()
            : Get.put(TestCartController());

}

Answer 3

原因 : 当Get.find() 在Get.put(Controller) 之前调用时发生。在初始化 Get.put() 之前调用 Get.find() 显示错误

解决方案 ：只需将 Get.put(controller) 调用到主 class 中，如下所示。那么来自任何 class 的 Get.find() 就会得到它。

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

class MyApp extends StatefulWidget {

  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final YourController controller = Get.put(YourController());
  ...
  
  @override
  Widget build(BuildContext context) {
  
    return MaterialApp(
    ......
  
}

Flutter Getx - "Xxx" 未找到。您需要调用 "Get.put(Xxx())" - 但我调用了 Get.put(Xxx())

Flutter Getx - "Xxx" not found. You need to call "Get.put(Xxx())" - But i have called Get.put(Xxx())

flutter

dart

flutter-get

flutter-getx

切线

例子