New Flutter Cloud Firestore [duplicate] - firebase

Question

This question already has answers here:
No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp() in Flutter and Firebase
(27 answers)
Closed 2 years ago.
I started to learn flutter again (started some time ago but stopped). You may find my code below. If I run the app on my smartphone it gives me the error: [core/no-app] No Firebase App['DEFAULT'} has been created - call Firebase.initializeApp(). I read in the documentation, but since I use the recent versions firebase_core: ^0.5.0, firebase_auth: ^0.18.0+1, cloud_firestore: ^0.14.0+2
it seems like the documentation isnt finished or I didnt get it. Where do I need to initialize that one? Why isnt that one enough: CollectionReference users = FirebaseFirestore.instance.collection('users');
timeline.dart (code is mostly from flutter getting started):
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:example/widgets/header.dart';
import 'package:example/widgets/progress.dart';
class Timeline extends StatefulWidget {
#override
_TimelineState createState() => _TimelineState();
}
class _TimelineState extends State<Timeline> {
#override
void initState() {
// getUserById();
super.initState();
}
#override
Widget build(BuildContext context) {
CollectionReference users = FirebaseFirestore.instance.collection('users');
return 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");
}
return new ListView(
children: snapshot.data.documents.map((DocumentSnapshot document) {
return new ListTile(
title: new Text(document.data()['username']),
subtitle: new Text(document.data()['posts_count']),
);
}).toList(),
);
},
);
}
}
This is my code for main.dart
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'pages/home.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Example',
debugShowCheckedModeBanner: false,
theme: ThemeData(
primarySwatch: Colors.red,
accentColor: Colors.blue,
),
home: Home(),
);
}
}
Thank you so much in advance!

Answer 1

In your main.dart, add the following
void main() async {
WidgetsFlutterBinding.ensureInitialized(); //add this
await Firebase.initializeApp(); //initialize here
runApp(MyApp());
}
Visit the new docs to learn more about working with the firebase packages

Answer 2

You can modify your MyApp widget like this, to make things work.
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
home: FutureBuilder(
future: Firebase.initializeApp(),
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
if (snapshot.hasError) {
print(snapshot.error.toString());
return Center(child: Text('Error'));
} else {
// ! RETURN THE SCREEN YOU WANT HERE
return Timeline();
}
},
),
);
}
}