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突然之间，我收到错误消息DataStore plugin has not been added to Amplify, recoverySuggestion: Add DataStore plugin to Amplify and call configure before calling DataStore related APIs，排除了我在该页面上所做的任何工作，我在新页面上尝试了相同的结果。

我已经执行了amplify codegen models,amplify pull和amplify env pull. 也尝试过，flutter clean但我根本看不到任何变化。我真的很困惑，似乎无法弄清楚这个问题。

我在调试时注意到的一件事是initState屏幕的 似乎更早地作为configureAmplify回调执行。

我将展示代码的相关部分（抱歉，代码太长了）。

发布规范.yaml

dependencies:
  ...
  amplify_flutter: ^0.2.10
  amplify_datastore: ^0.2.10
  amplify_api: ^0.2.10
  amplify_auth_cognito: ^0.2.10
  amplify_storage_s3: ^0.2.10

main.dart

import 'package:flutter/material.dart';
import 'package:my_package/screens/main/teams_screen.dart';
import 'package:my_package/services/amplify_services.dart';

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

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

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

class _MyAppState extends State<MyApp> {
  @override
  void initState() {
    super.initState();
    AmplifyService.configureAmplify();
  }

  @override
  Widget build(BuildContext context) {
  ...
  }
}

服务/amplify_services.dart

import 'package:flutter/foundation.dart';
import 'package:amplify_flutter/amplify.dart';
import 'package:amplify_datastore/amplify_datastore.dart';
import 'package:amplify_api/amplify_api.dart';
import 'package:amplify_auth_cognito/amplify_auth_cognito.dart';
import 'package:amplify_storage_s3/amplify_storage_s3.dart';
import 'package:my_package/models/ModelProvider.dart';
import 'package:my_package/amplifyconfiguration.dart';

class AmplifyService {
  static configureAmplify() async {
    AmplifyAPI apiPlugin = AmplifyAPI();
    AmplifyAuthCognito authPlugin = AmplifyAuthCognito();
    AmplifyStorageS3 amplifyStorageS3 = AmplifyStorageS3();
    AmplifyDataStore dataStorePlugin = AmplifyDataStore(
      modelProvider: ModelProvider.instance,
    );

    await Amplify.addPlugins([
      dataStorePlugin,
      authPlugin,
      amplifyStorageS3,
      apiPlugin,
    ]);

    try {
      await Amplify.configure(amplifyconfig);
    } on AmplifyAlreadyConfiguredException {
      if (kDebugMode) {
        print(
            "Amplify was already configured. Looks like app restarted on android.");
      }
    }
  }
}

最后是非常基本的页面，甚至没有输出（screens/teams_screen.dart）

import 'dart:async';
import 'package:amplify_datastore/amplify_datastore.dart';
import 'package:amplify_flutter/amplify.dart';
import 'package:flutter/material.dart';
import 'package:my_package/models/Team.dart';

class TeamsScreen extends StatefulWidget {
  const TeamsScreen({Key? key}) : super(key: key);

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

class _TeamsScreenState extends State<TeamsScreen> {
  late StreamSubscription<QuerySnapshot<Team>> _teamsSubscription;
  bool _isLoading = true;
  List<Team> teams = [];

  @override
  void initState() {
    super.initState();
    _initializeApp();
  }

  @override
  void dispose() {
    _teamsSubscription.cancel();
    super.dispose();
  }

  Future<void> _initializeApp() async {
    _teamsSubscription = Amplify.DataStore.observeQuery(Team.classType)
        .listen((QuerySnapshot<Team> snapshot) {
      setState(() {
        if (_isLoading) _isLoading = false;
        teams = snapshot.items;
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Container();
  }
}
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1 回答 1

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新的一天，新的心灵。这个问题很简单，我没有设置一个_isLoading状态来指示configureAmplify回调是否完成，让应用程序继续加载所有其他触发错误的屏幕。因此，在设置状态并仅在状态更改后添加应用程序的其余部分后，它可以正常工作。

为了解决它，我做了以下事情：

import 'package:flutter/material.dart';
import 'package:my_package/screens/main/teams_screen.dart';
import 'package:my_package/services/amplify_services.dart';

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

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

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

class _MyAppState extends State<MyApp> {
  @override
  void initState() {
    super.initState();
    _initializeApp();
  }

  Future<void> _initializeApp() async {
    await AmplifyService.configureAmplify(); // note the await!

    setState(() {
      _isLoading = false; // important to set the state!
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: _isLoading 
          ? Center(child: CircularProgressIndicator())
          : const MainScreen(), // _isLoading is very important here.
    );
  }
}
于 2022-01-18T11:41:28.207 回答