flutter firebase streambuilder返回null错误答案

【问题标题】：flutter firebase streambuilder gives returned null errorflutter firebase streambuilder返回null错误
【发布时间】：2021-01-28 10:27:00
【问题描述】：

我正在尝试通过颤振从我的 firebase firestore 数据库中实时读取数据。我了解到管理这个的最好方法是streambuilder。检查了有关此主题的一些站点并编写了如下代码并添加了打印语句以查看是否一切正常，但是当我运行该程序时，它会出现以下错误：

A build function returned null.
The relevant error-causing widget was: 
  StreamBuilder<DocumentSnapshot> file:///C:/Users/faruk/Desktop/3-sayiavi/sayi_avi/lib/gamescreen.dart:116:15

The method '[]' was called on null.
Receiver: null
Tried calling: []("status")
The relevant error-causing widget was: 
  StreamBuilder<DocumentSnapshot> file:///C:/Users/faruk/Desktop/3-sayiavi/sayi_avi/lib/gamescreen.dart:116:15

我的代码如下：

    import 'package:flutter/material.dart';
import 'package:assets_audio_player/assets_audio_player.dart';
import 'numbers.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';


Numbers myNumbers = Numbers();

void main(){
  runApp(
      GameScreen()
  );
}
class GameScreen extends StatefulWidget {
  static String id ='gamescreen';
  @override
  _GameScreenState createState() => _GameScreenState();
}

class _GameScreenState extends State<GameScreen> {
  final _auth =FirebaseAuth.instance;
  FirebaseUser loggedInUser;
  final _firestore = Firestore.instance;
  String collectionPath = 'users';
  String docPath;

  @override
  void initState(){
    super.initState();
    getCurrentUser();
  }
  
  void getCurrentUser() async{
    try{
      final user = await _auth.currentUser();
      if(user !=null){
        loggedInUser =user;
        docPath = loggedInUser.uid;
        print(docPath);
        print(collectionPath);
      }
    }catch(e){
      print(e);
    }
  }


  Expanded attachNumber(imagenumber){
    return Expanded(
      child:FlatButton(
        onPressed: (){
          setState(() {
            if(!myNumbers.numberStatus[1]){
              myNumbers.buttonValues['numberimage1'] = imagenumber;
              myNumbers.numberStatus[1] =true;
            }else if(!myNumbers.numberStatus[2]){
              myNumbers.buttonValues['numberimage2'] = imagenumber;
              myNumbers.numberStatus[2] =true;
            }else if(!myNumbers.numberStatus[3]){
              myNumbers.buttonValues['numberimage3'] = imagenumber;
              myNumbers.numberStatus[3] =true;
            }else if(!myNumbers.numberStatus[4]){
              myNumbers.buttonValues['numberimage4'] = imagenumber;
              myNumbers.numberStatus[4] =true;
            }
          });
          final assetsAudioPlayer = AssetsAudioPlayer();
          assetsAudioPlayer.open(
            Audio("assets/audios/click.wav"),
          );
        },
        padding: EdgeInsets.all(0),
        child: Image.asset('images/$imagenumber'),
      ),
    );
  }

  FlatButton showDeleteNumbers(statusNumber,number){
    return FlatButton(
      onPressed: (){
        setState(() {
          myNumbers.numberStatus[statusNumber] =false;
          myNumbers.buttonValues[number] = 'nonumber.png';
        });
      },
      child: Image.asset('images/'+myNumbers.buttonValues['$number']),
      //todo: _auth.signOut(); ekleyerek signout yapacaz
      //Navigator.pop(context); bir önceki ekrana dönecez;
    );
  }





  @override
  Widget build(BuildContext context) {

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.amberAccent,
          title: Text('Sayı Avı Oyun Ekranı'),
        ),
        body: StreamBuilder(
          stream: _firestore.collection(collectionPath).document(docPath).snapshots(),
          builder: (context,snapshot){
            if(snapshot.hasData){
              var userDocument = snapshot.data;
              print(userDocument['status']);
              return Column(
                children: <Widget>[
                  Expanded(
                    flex: 80,
                    child: Row(
                      children: <Widget>[
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getUserNumbers(),
                          ),
                        ),
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getOpponentNumbers(),
                          ),
                        ),
                      ],
                    ),
                  ),
                  Expanded(
                    flex:10,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        showDeleteNumbers(1,'numberimage1'),
                        showDeleteNumbers(2,'numberimage2'),
                        showDeleteNumbers(3,'numberimage3'),
                        showDeleteNumbers(4,'numberimage4'),
                      ],
                    ),
                  ),
                  Expanded(
                    flex: 10,
                    child: Row(
                      children: <Widget>[
                        attachNumber('one.png'),
                        attachNumber('two.png'),
                        attachNumber('three.png'),
                        attachNumber('four.png'),
                        attachNumber('five.png'),
                        attachNumber('six.png'),
                        attachNumber('seven.png'),
                        attachNumber('eight.png'),
                        attachNumber('nine.png'),
                        attachNumber('zero.png'),
                      ],
                    ),
                  ),
                ],
              );
            }
          },
        ),
      ),
    );
  }
}

把代码改成这样：

import 'package:flutter/material.dart';
import 'package:assets_audio_player/assets_audio_player.dart';
import 'numbers.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';


Numbers myNumbers = Numbers();

void main(){
  runApp(
      GameScreen()
  );
}
class GameScreen extends StatefulWidget {
  static String id ='gamescreen';
  @override
  _GameScreenState createState() => _GameScreenState();
}

class _GameScreenState extends State<GameScreen> {
  final _auth =FirebaseAuth.instance;
  FirebaseUser loggedInUser;
  final _firestore = Firestore.instance;
  String collectionPath = 'users';
  String docPath;

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

  void getCurrentUser() async{
    try{
      final user = await _auth.currentUser();
      if(user !=null){
        loggedInUser =user;
        docPath = loggedInUser.uid;
        print(docPath);
        print(collectionPath);
      }
    }catch(e){
      print(e);
    }
  }


  Expanded attachNumber(imagenumber){
    return Expanded(
      child:FlatButton(
        onPressed: (){
          setState(() {
            if(!myNumbers.numberStatus[1]){
              myNumbers.buttonValues['numberimage1'] = imagenumber;
              myNumbers.numberStatus[1] =true;
            }else if(!myNumbers.numberStatus[2]){
              myNumbers.buttonValues['numberimage2'] = imagenumber;
              myNumbers.numberStatus[2] =true;
            }else if(!myNumbers.numberStatus[3]){
              myNumbers.buttonValues['numberimage3'] = imagenumber;
              myNumbers.numberStatus[3] =true;
            }else if(!myNumbers.numberStatus[4]){
              myNumbers.buttonValues['numberimage4'] = imagenumber;
              myNumbers.numberStatus[4] =true;
            }
          });
          final assetsAudioPlayer = AssetsAudioPlayer();
          assetsAudioPlayer.open(
            Audio("assets/audios/click.wav"),
          );
        },
        padding: EdgeInsets.all(0),
        child: Image.asset('images/$imagenumber'),
      ),
    );
  }

  FlatButton showDeleteNumbers(statusNumber,number){
    return FlatButton(
      onPressed: (){
        setState(() {
          myNumbers.numberStatus[statusNumber] =false;
          myNumbers.buttonValues[number] = 'nonumber.png';
        });
      },
      child: Image.asset('images/'+myNumbers.buttonValues['$number']),
      //todo: _auth.signOut(); ekleyerek signout yapacaz
      //Navigator.pop(context); bir önceki ekrana dönecez;
    );
  }





  @override
  Widget build(BuildContext context) {

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.amberAccent,
          title: Text('Sayı Avı Oyun Ekranı'),
        ),
        body: StreamBuilder<DocumentSnapshot>(
          stream: _firestore.collection(collectionPath).document(docPath).snapshots(),
          builder: (BuildContext context,AsyncSnapshot<DocumentSnapshot> snapshot){
            if (snapshot.hasError) {
              return Text('Something went wrong');
            }
            if (snapshot.connectionState == ConnectionState.waiting) {
              return Text("Loading");
            }
            if(snapshot.hasData){
              Map<String, dynamic> userDocument  = snapshot.data.data;
              print(userDocument);
              return Column(
                children: <Widget>[
                  Expanded(
                    flex: 80,
                    child: Row(
                      children: <Widget>[
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getUserNumbers(),
                          ),
                        ),
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getOpponentNumbers(),
                          ),
                        ),
                      ],
                    ),
                  ),
                  Expanded(
                    flex:10,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        showDeleteNumbers(1,'numberimage1'),
                        showDeleteNumbers(2,'numberimage2'),
                        showDeleteNumbers(3,'numberimage3'),
                        showDeleteNumbers(4,'numberimage4'),
                      ],
                    ),
                  ),
                  Expanded(
                    flex: 10,
                    child: Row(
                      children: <Widget>[
                        attachNumber('one.png'),
                        attachNumber('two.png'),
                        attachNumber('three.png'),
                        attachNumber('four.png'),
                        attachNumber('five.png'),
                        attachNumber('six.png'),
                        attachNumber('seven.png'),
                        attachNumber('eight.png'),
                        attachNumber('nine.png'),
                        attachNumber('zero.png'),
                      ],
                    ),
                  ),
                ],
              );
            }
          },
        ),
      ),
    );
  }
}

当前，当我单击保存按钮时，它会获取地图的值，但是当我在 avd 中返回和前进时，它会再次变为 null。可能有什么问题？

我想做的是，有一个 firebase 函数可以根据用户在数据库中的“状态”来匹配用户。当用户进入此屏幕时，其状态将在数据库中为“on”，当 firebase 功能找到另一个具有“on”状态的用户时，它将使他们的状态为“ready”或类似的状态。当用户的状态更改为“准备就绪”而不是显示例如“正在搜索比赛”屏幕时，它将更改为游戏屏幕，并且 2 ppl 将开始基于回合进行游戏。所以总结一下，一旦用户进入这个屏幕，它就应该开始监听其状态的变化。此外，由于它将是一个回合制游戏，它应该在以后继续侦听其他字段以了解数据库更改。我希望我能解释一下自己。

为下面的新依赖项更新了颤振 firebase 代码

import 'package:flutter/material.dart';
import 'package:assets_audio_player/assets_audio_player.dart';
import 'numbers.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';


Numbers myNumbers = Numbers();

void main(){
  runApp(
      GameScreen()
  );
}
class GameScreen extends StatefulWidget {
  static String id ='gamescreen';
  @override
  _GameScreenState createState() => _GameScreenState();
}

class _GameScreenState extends State<GameScreen> {
  final _auth =FirebaseAuth.instance;
  User loggedInUser;
  final _firestore = FirebaseFirestore.instance;
  final String collectionPath = 'users';
  String docPath;
  DocumentReference userdoc;

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


  void getCurrentUser() async{
    try{
      final user = await _auth.currentUser;
      if(user !=null){
        loggedInUser =user;
        docPath = loggedInUser.uid;
      }
    }catch(e){
      print(e);
    }
  }


  Expanded attachNumber(imagenumber){
    return Expanded(
      child:FlatButton(
        onPressed: (){
          setState(() {
            if(!myNumbers.numberStatus[1]){
              myNumbers.buttonValues['numberimage1'] = imagenumber;
              myNumbers.numberStatus[1] =true;
            }else if(!myNumbers.numberStatus[2]){
              myNumbers.buttonValues['numberimage2'] = imagenumber;
              myNumbers.numberStatus[2] =true;
            }else if(!myNumbers.numberStatus[3]){
              myNumbers.buttonValues['numberimage3'] = imagenumber;
              myNumbers.numberStatus[3] =true;
            }else if(!myNumbers.numberStatus[4]){
              myNumbers.buttonValues['numberimage4'] = imagenumber;
              myNumbers.numberStatus[4] =true;
            }
          });
          final assetsAudioPlayer = AssetsAudioPlayer();
          assetsAudioPlayer.open(
            Audio("assets/audios/click.wav"),
          );
        },
        padding: EdgeInsets.all(0),
        child: Image.asset('images/$imagenumber'),
      ),
    );
  }

  FlatButton showDeleteNumbers(statusNumber,number){
    return FlatButton(
      onPressed: (){
        setState(() {
          myNumbers.numberStatus[statusNumber] =false;
          myNumbers.buttonValues[number] = 'nonumber.png';
        });
      },
      child: Image.asset('images/'+myNumbers.buttonValues['$number']),
    );
  }




  @override
  Widget build(BuildContext context) {
    userdoc = _firestore.collection(collectionPath).doc(docPath);
    return StreamBuilder<DocumentSnapshot>(
      stream: userdoc.snapshots(),
      builder: (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
        if (snapshot.hasError) {
          return Text('Something went wrong');
        }

        if (snapshot.connectionState == ConnectionState.waiting) {
          return Text("Loading");
        }
        if(snapshot.hasData){
          Map<String, dynamic> userDocument  = snapshot.data.data();
          print(collectionPath);
          print(docPath);
          print(snapshot.data);
          print(userDocument);
          return MaterialApp(
            home:Scaffold(
              appBar: AppBar(
                backgroundColor: Colors.amberAccent,
                title: Text('Sayı Avı Oyun Ekranı'),
              ),
              body:Column(
                children: <Widget>[
                  Expanded(
                    flex: 80,
                    child: Row(
                      children: <Widget>[
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getUserNumbers(),
                          ),
                        ),
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getOpponentNumbers(),
                          ),
                        ),
                      ],
                    ),
                  ),
                  Expanded(
                    flex:10,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        showDeleteNumbers(1,'numberimage1'),
                        showDeleteNumbers(2,'numberimage2'),
                        showDeleteNumbers(3,'numberimage3'),
                        showDeleteNumbers(4,'numberimage4'),
                      ],
                    ),
                  ),
                  Expanded(
                    flex: 10,
                    child: Row(
                      children: <Widget>[
                        attachNumber('one.png'),
                        attachNumber('two.png'),
                        attachNumber('three.png'),
                        attachNumber('four.png'),
                        attachNumber('five.png'),
                        attachNumber('six.png'),
                        attachNumber('seven.png'),
                        attachNumber('eight.png'),
                        attachNumber('nine.png'),
                        attachNumber('zero.png'),
                      ],
                    ),
                  ),
                ],
              ),
            ),
          );
        }
      },
    );
  }
}

您可以看到有 4 个打印件来检查我是否正确获取数据。目前，当我运行应用程序时，它会显示

I/flutter (15703)：用户我/颤振（15703）：viPK8SpL9MOIV2bQqGzBkKVdYAk2 I/flutter (15703): 'DocumentSnapshot' 的实例我/颤振（15703）：空

第 4 个不应该为空，当我在 android studio 中单击“保存”按钮时，我得到了

I/flutter (15703)：用户我/颤振（15703）：viPK8SpL9MOIV2bQqGzBkKVdYAk2 I/flutter (15703): 'DocumentSnapshot' 的实例 I/flutter (15703)：{密码：123456，输：0，赢：0，电子邮件：faruk@durusoy.net，状态：就绪}

哪个是正确的结果。

【问题讨论】：

也许添加一些其他小部件，如 CircularProgressIndicator，这可能是错误，因为数据仍在加载您的流没有返回任何小部件
@Reign 更改了上面的代码，当我单击保存按钮时，它会获取数据库中的所有值，但是当我在 avd 中单击后退和前进时，它会收到 null。
尝试直接在流中使用uid。就像流文档路径中的 _auth.currentUser().uid。

标签： flutter google-cloud-firestore stream-builder

【解决方案1】：

您忘记在 StreamBuilder 中对 snapshots() 的结果调用 data()。

var userDocument = snapshot.data.data();

请参考：https://firebase.flutter.dev/docs/firestore/usage/#realtime-changes

【讨论】：

更改了上面的代码，当我点击保存按钮时，它会获取数据库中的所有值，但是当我在 avd 中单击后退和前进时，它会收到 null。
我不明白。你能详细说明一下流程吗？
当我在 android studio 中单击保存按钮时，我会在控制台中收到所有信息，例如 I/flutter（5096）：{密码：123456，输：0，赢：0，电子邮件：faruk@gmail .com，状态：关闭} 但是当我单击 android 虚拟设备中的后退按钮然后重新进入此屏幕（dart 文件）时，它会收到 null。首次加载时也是如此。当我点击 android studio 中的保存按钮时它才起作用，这有点奇怪。

【解决方案2】：

我认为当您返回上一屏幕时，initState and getCurrentUser() 函数不会再次调用，docPath is null 因此您应该从 Build 中调用此函数或以其他方式调用它并获取 @987654323 @

【讨论】：

我返回然后重新进入这个屏幕，仍然没有调用。当我保存代码时它只工作一次。
当我将 getCurrentUser() 放在小部件构建下时，它会两次获取 docpath 和收集路径（我在控制台中打印它们）但仍然为空，docpath 不为空，快照数据为空。

【解决方案3】：

首先你应该调用 initState 然后处理它。因为每次运行页面或更新页面时，您都会调用initState()，这就是为什么您可能再次丢失所有数据的原因。代码是这样的：

  void initState() {
    super.initState();
   getCurrentUser();
  }

  @override
  void dispose() {
    // : implement dispose
   getCurrentUser();
    super.dispose();
  }

如果这对阅读这段代码没有帮助。我有这个问题是因为QuerySnapshot 和DocumentSnapShot

 StreamBuilder<QuerySnapshot>(

        stream: Firestore.instance.collection("MyTodos").snapshots(),

        builder: (context, snapshots) {

          return ListView.builder(
            shrinkWrap: true,
            addAutomaticKeepAlives: true,
            itemCount: snapshots.data.documents.length,
           
            itemBuilder: (BuildContext context, int index) {

              DocumentSnapshot documentSnapshot =
                  snapshots.data.documents[index];

              return Card(              
                  margin: EdgeInsets.all(6),
                  elevation: 2.0,
                  child: ListTile(
                  title: Text(documentSnapshot.data["todoTitle"]),                     
                  ),               
              );
            },
          );
        },
      ),

根据您的错误。我将您的代码更改为这个，您可以在此链接上找到更多信息https://firebase.flutter.dev/docs/firestore/usage/#realtime-changes

@override
  Widget build(BuildContext context) {
final users = _firestore.collection(collectionPath).document(docPath);
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.amberAccent,
          title: Text('Sayı Avı Oyun Ekranı'),
        ),
        body: StreamBuilder<QuerySnapshot>(
          stream: users.snapshots(),
          builder: (BuildContext context,AsyncSnapshot<QuerySnapshot> snapshot){
            if (snapshot.hasError) {
              return Text('Something went wrong');
            }
            if (snapshot.connectionState == ConnectionState.waiting) {
              return Text("Loading");
            }
            if(snapshot.hasData){
              Map<String, dynamic> userDocument  = snapshot.data.documents;
              print(userDocument);
              return Column(
                children: <Widget>[
                  Expanded(
                    flex: 80,
                    child: Row(
                      children: <Widget>[
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getUserNumbers(),
                          ),
                        ),
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getOpponentNumbers(),
                          ),
                        ),
                      ],
                    ),
                  ),
                  Expanded(
                    flex:10,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        showDeleteNumbers(1,'numberimage1'),
                        showDeleteNumbers(2,'numberimage2'),
                        showDeleteNumbers(3,'numberimage3'),
                        showDeleteNumbers(4,'numberimage4'),
                      ],
                    ),
                  ),
                  Expanded(
                    flex: 10,
                    child: Row(
                      children: <Widget>[
                        attachNumber('one.png'),
                        attachNumber('two.png'),
                        attachNumber('three.png'),
                        attachNumber('four.png'),
                        attachNumber('five.png'),
                        attachNumber('six.png'),
                        attachNumber('seven.png'),
                        attachNumber('eight.png'),
                        attachNumber('nine.png'),
                        attachNumber('zero.png'),
                      ],
                    ),
                  ),
                ],
              );
            }
          },
        ),
      ),
    );
  }
}

【讨论】：

我真的不明白你要制作什么样的应用程序。但我认为如果您使用ListView.builder，您可以知道您制作的小部件的索引。
并确保你清理了你的颤振在终端flutter clean
添加了一些关于我想要达到的目标的信息。
你做这个页面的方式太错误了，你应该尝试将UI和逻辑分开。 be careful about firebase when you trying to use it inside flutter UI. because if you make any small bug you will be charged double price because of requesting to much time 。我将您的代码更新为此。
CollectionReference users = _firestore.collection(collectionPath).document(docPath);不起作用，它说不能将文档引用的值类型分配给collectionreference，如果我只设置CollectionReference users = _firestore.collection(collectionPath)，它可能会起作用，但我不想要它，因为它会从数据库中获取所有用户并且它将是浪费带宽（至少我的问题是这样）

【解决方案4】：

在尝试了 ahmed 的答案但没有解决方案后，我决定重新排列我的代码，就像这里 https://firebase.flutter.dev/docs/overview 一样，它终于奏效了。还升级了我的所有依赖项。

这是我的最终代码：

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


Numbers myNumbers = Numbers();

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

class GameScreen extends StatefulWidget {
  static String id ='gamescreen';

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

class _GameScreenState extends State<GameScreen> {
  bool _initialized = false;
  bool _error = false;

  void initializeFlutterFire() async {
    try {
      // Wait for Firebase to initialize and set `_initialized` state to true
      await Firebase.initializeApp();
      setState(() {
        _initialized = true;
      });
    } catch(e) {
      // Set `_error` state to true if Firebase initialization fails
      setState(() {
        _error = true;
      });
    }
  }

  @override
  void initState() {
    initializeFlutterFire();
    super.initState();
    getCurrentUser();
  }

  final _auth =FirebaseAuth.instance;
  User loggedInUser;
  final _firestore = FirebaseFirestore.instance;
  final String collectionPath = 'users';
  String docPath;
  DocumentReference userdoc;


  void getCurrentUser() async{
    try{
      final user = await _auth.currentUser;
      if(user !=null){
        loggedInUser =user;
        docPath = loggedInUser.uid;
      }
    }catch(e){
      print(e);
    }
  }


  Expanded attachNumber(imagenumber){
    return Expanded(
      child:FlatButton(
        onPressed: (){
          setState(() {
            if(!myNumbers.numberStatus[1]){
              myNumbers.buttonValues['numberimage1'] = imagenumber;
              myNumbers.numberStatus[1] =true;
            }else if(!myNumbers.numberStatus[2]){
              myNumbers.buttonValues['numberimage2'] = imagenumber;
              myNumbers.numberStatus[2] =true;
            }else if(!myNumbers.numberStatus[3]){
              myNumbers.buttonValues['numberimage3'] = imagenumber;
              myNumbers.numberStatus[3] =true;
            }else if(!myNumbers.numberStatus[4]){
              myNumbers.buttonValues['numberimage4'] = imagenumber;
              myNumbers.numberStatus[4] =true;
            }
          });
          final assetsAudioPlayer = AssetsAudioPlayer();
          assetsAudioPlayer.open(
            Audio("assets/audios/click.wav"),
          );
        },
        padding: EdgeInsets.all(0),
        child: Image.asset('images/$imagenumber'),
      ),
    );
  }

  FlatButton showDeleteNumbers(statusNumber,number){
    return FlatButton(
      onPressed: (){
        setState(() {
          myNumbers.numberStatus[statusNumber] =false;
          myNumbers.buttonValues[number] = 'nonumber.png';
        });
      },
      child: Image.asset('images/'+myNumbers.buttonValues['$number']),
    );
  }




  @override
  Widget build(BuildContext context) {
    userdoc = _firestore.collection(collectionPath).doc(docPath);
    if(_error) {
      return Text('error-game', textDirection: TextDirection.ltr);
    }

    // Show a loader until FlutterFire is initialized
    if (!_initialized) {
      return Text('Loading', textDirection: TextDirection.ltr);
    }
    return StreamBuilder<DocumentSnapshot>(
      stream: userdoc.snapshots(),
      builder: (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
        if (snapshot.hasError) {
          return Text('Something went wrong');
        }

        if (snapshot.connectionState == ConnectionState.waiting) {
          return Text("Loading");
        }
        if(snapshot.hasData){
          Map<String, dynamic> userDocument  = snapshot.data.data();
          print(collectionPath);
          print(docPath);
          print(snapshot.data);
          print(userDocument);
          return MaterialApp(
            home:Scaffold(
              appBar: AppBar(
                backgroundColor: Colors.amberAccent,
                title: Text('Sayı Avı Oyun Ekranı'),
              ),
              body:Column(
                children: <Widget>[
                  Expanded(
                    flex: 80,
                    child: Row(
                      children: <Widget>[
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getUserNumbers(),
                          ),
                        ),
                        Expanded(
                          flex: 50,
                          child: Column(
                            children: myNumbers.getOpponentNumbers(),
                          ),
                        ),
                      ],
                    ),
                  ),
                  Expanded(
                    flex:10,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        showDeleteNumbers(1,'numberimage1'),
                        showDeleteNumbers(2,'numberimage2'),
                        showDeleteNumbers(3,'numberimage3'),
                        showDeleteNumbers(4,'numberimage4'),
                      ],
                    ),
                  ),
                  Expanded(
                    flex: 10,
                    child: Row(
                      children: <Widget>[
                        attachNumber('one.png'),
                        attachNumber('two.png'),
                        attachNumber('three.png'),
                        attachNumber('four.png'),
                        attachNumber('five.png'),
                        attachNumber('six.png'),
                        attachNumber('seven.png'),
                        attachNumber('eight.png'),
                        attachNumber('nine.png'),
                        attachNumber('zero.png'),
                      ],
                    ),
                  ),
                ],
              ),
            ),
          );
        }
      },
    );
  }
}

【讨论】：