如何从 Flutter firebase firestore 数据库中获取这些数据？

Question

我是编码新手，使用flutter firebase firestore我想获取数据（目前是从服务器手动添加的。附加我的代码

主要.dart

import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'package:quizzy/screens/PhysicsNew.dart';
import 'package:quizzy/screens/showAnswer.dart';
import 'package:quizzy/screens/home.dart';
import 'package:quizzy/screens/physics.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(const Quizzy());
}

class Quizzy extends StatelessWidget {
  const Quizzy({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(title: 'Flutter Demo', initialRoute: '/', routes: {
      '/': (context) => Home(),
      '/physics': (context) => Physics(),
      '/physicsNew': (context) => PhysicsNew(),
      '/showAnswers': (context) => ShowAnswer(),
    });
  }
}

物理.dart

    import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';

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

  @override
  State<PhysicsNew> createState() => _PhysicsNewState();
}

class _PhysicsNewState extends State<PhysicsNew> {
  final Stream<QuerySnapshot> questionList =
      FirebaseFirestore.instance.collection('QuestionList').snapshots();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Title')),
      body: Container(
          child: StreamBuilder<QuerySnapshot>(
              stream: questionList,
              builder: (
                BuildContext context,
                AsyncSnapshot<QuerySnapshot> Snapshot,
              ) {
                //
                if (Snapshot.hasError) {
                  return Text('Something went wrong');
                }
                if (Snapshot.connectionState == ConnectionState.waiting) {
                  Text('Loading');
                }
                final data = Snapshot.requireData;
                return ListView.builder(
                    itemCount: data.size,
                    itemBuilder: (context, index) {
                      return Text(data.docs[index]['Question']);
                    });
              })),
    );
  }
}

发布规范.yaml

name: quizzy
description: Made by *****.com

publish_to: 'none' # Remove this line if you wish to publish to pub.dev

#
version: 1.0.0+1

environment:
  sdk: ">=2.17.3 <3.0.0"


dependencies:
  flutter:
    sdk: flutter


 
  cupertino_icons: ^1.0.2
  firebase_core: ^1.3.0
  cloud_firestore: ^2.2.2
  firebase_auth: ^3.3.20

dev_dependencies:
  flutter_test:
    sdk: flutter

  
  flutter_lints: ^2.0.0


flutter:

  uses-material-design: true
 

我正在尝试从 firestore 手动添加数据。 在图像中附加我的数据库详细信息。

我是新来的，尝试了各种事情，但它变得复杂和混乱，所以有人可以帮助我，感谢帮助。 ！

我在调试控制台中遇到的错误

E/flutter ( 6922): [ERROR:flutter/lib/ui/ui_dart_state.cc(198)] Unhandled Exception: [core/not-initialized] Firebase has not been correctly initialized.
E/flutter ( 6922): Usually this means you've attempted to use a Firebase service before calling `Firebase.initializeApp`.

E/flutter ( 6922): View the documentation for more information: https://firebase.flutter.dev/docs/overview#initialization
E/flutter ( 6922): #0      MethodChannelFirebase.initializeApp
E/flutter ( 6922): <asynchronous suspension>
E/flutter ( 6922): #1      Firebase.initializeApp
E/flutter ( 6922): #

2 主要

Answer 1

通常这意味着您在调用Firebase.initializeApp之前尝试使用 Firebase 服务。

您没有将任何配置数据传递给对initializeApp的调用，这意味着 Firebase SDK 无法初始化其与服务器上您的项目的连接。

我建议遵循 Firebase 文档中关于设置 SDK的指导，其中：

1. 使用flutterfire CLI 生成一个firebase-options.dart文件，

2. 然后将此 firebase firebase-options.dart文件导入您的main.dart 。

3. 最后将配置选项传递给 Firebase SDK，如下所示：

    await Firebase.initializeApp( options: DefaultFirebaseOptions.currentPlatform, );