Firebase NoSuchMethodError:在null上调用了getter数据,接收方:null
我试图创建一个详细屏幕来显示数据库中的Firebase数据,并显示图像以及一些文本数据,包括项目数量、日期和地理位置。有没有办法确定数据返回null的原因?导航器应该导航到DetailPage 这是我的主要文件-Firebase NoSuchMethodError:在null上调用了getter数据,接收方:null,firebase,flutter,dart,firebase-storage,Firebase,Flutter,Dart,Firebase Storage,我试图创建一个详细屏幕来显示数据库中的Firebase数据,并显示图像以及一些文本数据,包括项目数量、日期和地理位置。有没有办法确定数据返回null的原因?导航器应该导航到DetailPage 这是我的主要文件- import 'package:cloud_firestore/cloud_firestore.dart'; import 'package:flutter/material.dart'; import 'package:wasteagram/pages/create_waste.da
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:wasteagram/pages/create_waste.dart';
import 'package:wasteagram/services/crud.dart';
import 'pages/create_waste.dart';
import 'pages/detail_screen.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Wasteagram - ',
theme: new ThemeData(
primarySwatch: Colors.deepOrange,
),
home: new MyHomePage(title: 'Wasteagram - '),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
CrudMethods crudMethods = new CrudMethods();
Stream wasteStream;
Widget WasteList() {
return Container(
child: wasteStream != null ? Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
StreamBuilder(
stream: wasteStream,
builder: (context, snapshot) {
return ListView.builder(
padding: EdgeInsets.symmetric(horizontal: 16),
itemCount: snapshot.data.documents.length,
shrinkWrap: true,
itemBuilder: (context, index){
return WidgetTile(
wastedate:
snapshot.data.documents[index].data['wastedate'],
wastenumber:
snapshot.data.documents[index].data['wastenumber']
);
});
},)
],
) : Container(
alignment: Alignment.center,
child: CircularProgressIndicator(),
),
);
}
void initState() {
super.initState();
crudMethods.getData().then((result) {
wasteStream = result;
});
}
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text(widget.title),
),
body: WasteList(),
floatingActionButton: new FloatingActionButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => CameraScreen())
);
},
child: new Icon(Icons.add),
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
);
}
}
class WidgetTile extends StatelessWidget {
String wastedate, wastenumber;
WidgetTile({@required this.wastedate, @required this.wastenumber});
@override
Widget build(BuildContext context) {
return ListTile(
title: Text(wastedate),
trailing: Text(wastenumber),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => DetailPage())
);
}
);
}
}
import'包:cloud_firestore/cloud_firestore.dart';
进口“包装:颤振/材料.省道”;
导入“package:wasteagram/pages/create_waste.dart”;
导入“包装:wasteagram/services/crud.dart”;
导入“页面/创建_waste.dart”;
导入“页面/详细信息_screen.dart”;
void main()=>runApp(新的MyApp());
类MyApp扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回新材料PP(
标题:“废弃地”,
主题:新主题数据(
primarySwatch:颜色。深橙色,
),
主页:我的新主页(标题:“Wasteagram-”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
CrudMethods CrudMethods=新的CrudMethods();
废物流;
小部件废弃列表(){
返回容器(
子级:废物流!=null?列(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
StreamBuilder(
溪流:废溪流,
生成器:(上下文,快照){
返回ListView.builder(
填充:边缘组。对称(水平:16),
itemCount:snapshot.data.documents.length,
收缩膜:对,
itemBuilder:(上下文,索引){
返回WidgetTile(
废弃日期:
snapshot.data.documents[index].data['wastedate'],
废物编号:
snapshot.data.documents[index].data['wastenumber']
);
});
},)
],
):容器(
对齐:对齐.center,
子对象:CircularProgressIndicator(),
),
);
}
void initState(){
super.initState();
crudMethods.getData().then((结果){
废物流=结果;
});
}
@凌驾
小部件构建(构建上下文){
归还新脚手架(
appBar:新的appBar(
标题:新文本(widget.title),
),
正文:废物清单(),
floatingActionButton:新的floatingActionButton(
已按下:(){
导航器。推(
上下文
MaterialPage路由(生成器:(上下文)=>CameraScreen()
);
},
子:新图标(Icons.add),
),
浮动ActionButtonLocation:浮动ActionButtonLocation.centerFloat,
);
}
}
类WidgetTile扩展了无状态小部件{
字符串wastedate,wastenumber;
WidgetTile({@required this.wastedate,@required this.wastenumber});
@凌驾
小部件构建(构建上下文){
返回列表块(
标题:文本(废弃日期),
尾随:文本(编号),
onTap:(){
导航器。推(
上下文
MaterialPage路由(生成器:(上下文)=>DetailPage()
);
}
);
}
}
这是我的详细资料
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:wasteagram/data/firestore_service.dart';
class DetailPage extends StatefulWidget {
final DocumentSnapshot post;
DetailPage({this.post});
@override
_DetailPageState createState() => _DetailPageState();
}
class _DetailPageState extends State<DetailPage> {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.post.data["wastedate"])
),
body: Center(
child: Container(
child: Column(
children: <Widget> [
Image.network(widget.post.data["image"]),
Text(widget.post.data["wastedate"]),
Text(widget.post.data["wastenumber"]),
Text(widget.post.data["wastelocation"].toString()),
]
)
)
),
);
}
}
导入“包装:颤振/材料.省道”;
导入“包:cloud_firestore/cloud_firestore.dart”;
导入“包:wasteagram/data/firestore_service.dart”;
类DetailPage扩展StatefulWidget{
最后文件快照后;
DetailPage({this.post});
@凌驾
_DetailPageState createState()=>\u DetailPageState();
}
类_DetailPageState扩展状态{
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:文本(widget.post.data[“wastedate”])
),
正文:中(
儿童:货柜(
子:列(
儿童:[
Image.network(widget.post.data[“Image”]),
文本(widget.post.data[“wastedate”]),
文本(widget.post.data[“wastenumber”]),
文本(widget.post.data[“wastelocation”].toString()),
]
)
)
),
);
}
}
您没有将DocumentSnapshot传递到详细信息页面。
试试这个:
Widget WasteList() {
return Container(
child: wasteStream != null ? Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
StreamBuilder(
stream: wasteStream,
builder: (context, snapshot) {
return ListView.builder(
padding: EdgeInsets.symmetric(horizontal: 16),
itemCount: snapshot.data.documents.length,
shrinkWrap: true,
itemBuilder: (context, index){
return WidgetTile(
wastedate:
snapshot.data.documents[index].data['wastedate'],
wastenumber:
snapshot.data.documents[index].data['wastenumber'],
post:
snapshot.data.documents[index]
);
});
},)
],
) : Container(
alignment: Alignment.center,
child: CircularProgressIndicator(),
),
);
}
class WidgetTile extends StatelessWidget {
String wastedate, wastenumber;
DocumentSnapshot post;
WidgetTile({@required this.wastedate, @required this.wastenumber,@required this.post});
@override
Widget build(BuildContext context) {
return ListTile(
title: Text(wastedate),
trailing: Text(wastenumber),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => DetailPage(post: post))
);
}
);
}
}
Widget废物清单(){
返回容器(
子级:废物流!=null?列(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
StreamBuilder(
溪流:废溪流,
生成器:(上下文,快照){
返回ListView.builder(
填充:边缘组。对称(水平:16),
itemCount:snapshot.data.documents.length,
收缩膜:对,
itemBuilder:(上下文,索引){
返回WidgetTile(
废弃日期:
snapshot.data.documents[index].data['wastedate'],
废物编号:
snapshot.data.documents[index].data['wastenumber'],
职位:
快照.数据.文档[索引]
);
});
},)
],
):容器(
对齐:对齐.center,
子对象:CircularProgressIndicator(),
),
);
}
类WidgetTile扩展了无状态小部件{
字符串wastedate,wastenumber;
文档快照帖子;
WidgetTile({@required this.wastedate,@required this.wastenumber,@required this.post});
@凌驾
小部件构建(构建上下文){
返回列表块(
标题:文本(废弃日期),
尾随:文本(编号),
onTap:(){
导航器。推(
上下文
MaterialPageRoute(生成器:(上下文)=>DetailPage(post:post))
);
}
);
}
}