[英]How to Get Simple Data From Cloud Firestore For Flutter App?
When I Run getting following error. 当我运行时出现以下错误。 These are basic code for flutter into firebase. 这些是扑入Firebase的基本代码。
The following assertion was thrown building MyHomePage(dirty, state: MyHomePageState#b163a): 'package:flutter/src/widgets/text.dart': Failed assertion: line 235 pos 15: 'data != null': is not 构建MyHomePage(脏,状态:MyHomePageState#b163a)时引发了以下断言:'package:flutter / src / widgets / text.dart':失败的断言:235行pos 15:'data!= null':不是
Please, Can Anyone Help me How to Resolve This? 请,有人可以帮我解决这个问题吗?
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
Future<void> main() async {
final FirebaseApp app = await FirebaseApp.configure(
name: 'vscodefirebase',
options: const FirebaseOptions(
googleAppID: 'xxx',
gcmSenderID: 'xxx',
apiKey: 'xxxx',
projectID: 'vscodefirebase',
),
);
final Firestore firestore = Firestore(app: app);
await firestore.settings(timestampsInSnapshotsEnabled: true);
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Firebase',
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
MyHomePageState createState() => MyHomePageState();
}
class MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: StreamBuilder<QuerySnapshot>(
stream: Firestore.instance.collection('books').snapshots(),
builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (!snapshot.hasData) return new Text('Loading...');
return new ListView(
children: snapshot.data.documents.map((DocumentSnapshot document) {
return new ListTile(
title: new Text(document['title']),
subtitle: new Text(document['author']),
);
}).toList(),
);
},
),
);
}
}
You have a Text widget with null text. 您有一个带有空文本的文本小部件。
Here, you did not enter title property for MyHomePage 在这里,您没有输入MyHomePage的标题属性
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Firebase',
home: MyHomePage(),
);
}
}
So this Text widget has null text value. 因此,此“文本”小部件具有空文本值。
appBar: AppBar(
title: Text(widget.title),
),
To solve this, declare MyHomePage like this: 为了解决这个问题,像这样声明MyHomePage:
MyHomePage(title: "My Home Page")
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