Flutter Flatter firebase streambuilder返回空错误
我正试图通过Flatter从firebase firestore数据库中实时读取数据。我了解到最好的管理方法是streambuilder。在这个主题上检查了一些站点，编写了如下代码，并放置了一个print语句，只是为了看看是否一切正常，但是当我运行程序时，它会给出一些错误：Flutter Flatter firebase streambuilder返回空错误,flutter,google-cloud-firestore,stream-builder,Flutter,Google Cloud Firestore,Stream Builder,我正试图通过Flatter从firebase firestore数据库中实时读取数据。我了解到最好的管理方法是streambuilder。在这个主题上检查了一些站点，编写了如下代码，并放置了一个print语句，只是为了看看是否一切正常，但是当我运行程序时，它会给出一些错误： A build function returned null. The relevant error-causing widget was: StreamBuilder<DocumentSnapshot>
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
生成函数返回null。
导致错误的相关小部件是：
StreamBuilderfile:///C:/Users/faruk/Desktop/3-sayiavi/sayi_avi/lib/gamescreen.飞镖：116:15
对null调用了方法“[]”。
收件人：空
已尝试呼叫：[]（“状态”）
导致错误的相关小部件是：
StreamBuilderfile:///C:/Users/faruk/Desktop/3-sayiavi/sayi_avi/lib/gamescreen.飞镖：116:15
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'),
],
),
),
],
);
}
},
),
),
);
}
}
导入“包装：颤振/材料.省道”；
导入“package:assets_audio_player/assets_audio_player.dart”；
输入“数字.省道”；
导入“包：firebase_auth/firebase_auth.dart”；
导入“包：cloud_firestore/cloud_firestore.dart”；
数字myNumbers=数字（）；
void main（）{
runApp(
游戏屏幕（）
);
}
类GameScreen扩展StatefulWidget{
静态字符串id='gamescreen'；
@凌驾
_GameScreeenState（）=>\u GameScreeenState（）；
}
类_GameScreenState扩展状态{
final _auth=FirebaseAuth.instance；
FirebaseUser日志用户；
final _firestore=firestore.instance；
字符串collectionPath='users'；
字符串路径；
@凌驾
void initState（）{
super.initState（）；
getCurrentUser（）；
}
void getCurrentUser（）异步{
试一试{
最终用户=等待_auth.currentUser（）；
如果（用户！=null）{
loggedInUser=用户；
docPath=loggedInUser.uid；
打印（docPath）；
打印（收集路径）；
}
}捕获（e）{
印刷品（e）；
}
}
扩展附件编号（图像编号）{
扩大回报(
孩子：扁平按钮(
已按下：（）{
设置状态（）{
如果（！myNumbers.numberStatus[1]）{
myNumbers.ButtonValue['numberimage1']=imagenumber；
myNumbers.numberStatus[1]=true；
}如果（！myNumbers.numberStatus[2]）{
myNumbers.ButtonValue['numberimage2']=imagenumber；
myNumbers.numberStatus[2]=true；
}如果（！myNumbers.numberStatus[3]）{
myNumbers.ButtonValue['numberimage3']=imagenumber；
myNumbers.numberStatus[3]=true；
}如果（！myNumbers.numberStatus[4]）{
myNumbers.ButtonValue['numberimage4']=imagenumber；
myNumbers.numberStatus[4]=true；
}
});
最终assetsAudioPlayer=assetsAudioPlayer（）；
assetsAudioPlayer.open(
音频（“资产/音频/点击.wav”），
);
},
填充：边缘集。全部（0），
子项：Image.asset（'images/$imagenumber'），
),
);
}
FlatButton ShowDeleteNumber（状态编号、编号）{
返回按钮(
已按下：（）{
设置状态（）{
myNumbers.numberStatus[statusNumber]=false；
myNumbers.buttonvalue[number]=“nonnumber.png”；
});
},
子项：Image.asset（'images/'+myNumbers.buttonvalue['$number']），
//todo:_auth.signOut（）；ekleyerek signOut yapacaz
//Navigator.pop（上下文）；birönceki ekrana dönecez；
);
}
@凌驾
小部件构建（构建上下文）{
返回材料PP(
家：脚手架(
appBar:appBar(
背景颜色：Colors.amberAccent，
标题：文本（“SayıAvıOyun Ekranı”），
),
正文：StreamBuilder(
流：_firestore.collection（collectionPath）.document（docPath.snapshots（），
生成器：（上下文，快照）{
if（snapshot.hasData）{
var userDocument=snapshot.data；
打印（用户文档['status']）；
返回列(
儿童：[
扩大(
弹性：80，
孩子：排(
儿童：[
扩大(
弹性：50，
子：列(
子项：myNumbers.getUserNumbers（），
),
),
扩大(
弹性：50，
子：列(
子项：myNumbers.getOpponentNumbers（），
),
),
],
),
),
扩大(
弹性：10，
孩子：排(
mainAxisAlignment:mainAxisAlignment.center，
儿童：[
ShowDeleteNumber（1，'numberimage1'），
ShowDeleteNumber（2，'numberimage2'），
ShowDeleteNumber（3，'numberimage3'），
ShowDeleteNumber（4，'numberimage4'），
],
),
),
扩大(
弹性：10，
孩子：排(
儿童：[
附件编号（'one.png'），
附件编号（'two.png'），
附件编号（'three.png'），
附件编号（'four.png'），
附件编号（'five.png'），
附件编号（'six.png'），
附件编号（'seven.png'），
附件编号（'eight.png'），
附件编号（'nine.png'），
附件编号（'zero.png'），
],
),
),
],
);
}
},
),
),
);
}
}
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'),
],
),
),
],
);
}
},
),
),
);
}
}
void initState() {
super.initState();
getCurrentUser();
}
@override
void dispose() {
// : implement dispose
getCurrentUser();
super.dispose();
}
导入“包装：颤振/材料.省道”；
进口包装
void initState() {
super.initState();
getCurrentUser();
}
@override
void dispose() {
// : implement dispose
getCurrentUser();
super.dispose();
}
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"]),
),
);
},
);
},
),
@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'),
],
),
),
],
);
}
},
),
),
);
}
}
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'),
],
),
),
],
),
),
);
}
},
);
}
}