I'm getting an error on my IOS simulator when I run my flutter app.
The offending widget is: FutureBuilder Build functions must never return null. To return an empty space that causes the building widget to fill available room, return "Container()". To return an empty space that takes as little room as possible, return "new Container(width: 0.0, height: 0.0)
void main(){
WidgetsFlutterBinding.ensureInitialized();
runApp(App());
}
class App extends StatelessWidget {
final Future<FirebaseApp> _initialization = Firebase.initializeApp();
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(
primaryColor: Color(0xFF6A8D73),
primaryColorDark: Color(0xFF475E4D),
accentColor: Color(0xffCFE8D5),
primaryColorLight: Colors.white
),
home: FutureBuilder(
future: _initialization,
builder: (context, snapshot){
if (snapshot.hasError) {
print(snapshot.error);
return null;
}
if (snapshot.connectionState == ConnectionState.done) {
return HomePage();
}
return Splash();
},
)
);
}
}
class HomePage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider(
create: (_) => UserRepository.instance(),
child: Consumer(
builder: (context, UserRepository user, _){
switch(user.status){
case Status.Uninitialized:
return Splash();
case Status.Unauthenticated:
case Status.Authenticating:
return LoginPage();
case Status.Authenticated:
return TaskBar();
default:
return null;
}
},
),
);
}
}
class Splash extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Material(
child: Center(
child: Text("Splash Screen"),
),
);
}
}
You just have to replace the following code where you are checking for error-
if (snapshot.hasError) {
print(snapshot.error);
return SizedBox();
}
Related
When I run the code below, all I am getting now is.
I copied this code from another this post. This seems to work, prior to the last code I had, but I still am getting no success on retrieving any data. I tried the other things in the same post but I had no luck.
The method 'data' was called on null.
Receiver: null
Tried calling: data()
void main() {
runApp(myApp());
}
class myApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: FirstRoute(title: 'First Route'),
);
}
}
class FirstRoute extends StatefulWidget {
FirstRoute({Key key, this.title}) : super(key: key);
final String title;
#override
_FirstRouteState createState() => _FirstRouteState();
}
class _FirstRouteState extends State<FirstRoute> {
#override
void initState() {
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("test"),
),
body: FutureBuilder(
future: getData(),
builder: (context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
return Column(
children: [
Container(
height: 27,
child: Text(
"Name: ${snapshot.data.data()['Name']}",
overflow: TextOverflow.fade,
style: TextStyle(fontSize: 20),
),
),
],
);
} else if (snapshot.connectionState == ConnectionState.none) {
return Text("No data");
}
return CircularProgressIndicator();
},
));
}
Future<DocumentSnapshot> getData() async {
await Firebase.initializeApp();
return await FirebaseFirestore.instance
.collection("test")
.doc()
.get();
}
}
On the firestore website it says that there are some reads and there's also snapshots listeners active, but the error still persists.
Any recommendations and tips would be great. Thanks!
I'm trying to play a video from a URL of a Firestore Document. To play a video in Flutter, I have to instantiate its Url in the init() method. I set a default URL to a butterfly video, and the value was supposed to be replaced by the URL obtained from Firestore. (So that it is easy for me to see if the code works). However, the code does not work properly. I got an error that says "NoSuchMethodError: The getter 'value' was called on null".
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:video_player/video_player.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
void main() {
WidgetsFlutterBinding.ensureInitialized();
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// Create the initialization Future outside of build
final Future<FirebaseApp> _initialization = Firebase.initializeApp();
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return FutureBuilder(
future: _initialization,
builder: (context, snapshot) {
// Check for error
if (snapshot.hasError) {
print(snapshot.error);
return Center(
child: Container(
child: Text(
"Something went wrong",
textDirection: TextDirection.ltr,
),
),
);
}
//Once complete, show your application
if (snapshot.connectionState == ConnectionState.done) {
return MaterialApp(
title: 'Flutter Demo',
home: VideoPlayerScreen(),
);
}
return CircularProgressIndicator();
});
}
}
class VideoPlayerScreen extends StatefulWidget {
#override
_VideoPlayerScreenState createState() => _VideoPlayerScreenState();
}
class _VideoPlayerScreenState extends State<VideoPlayerScreen> {
VideoPlayerController _controller;
Future<void> _initializeVideoPlayerFuture;
FirebaseFirestore firestore = FirebaseFirestore.instance;
String videoUrl =
'https://flutter.github.io/assets-for-api-docs/assets/videos/butterfly.mp4';
#override
void initState() {
firestore.collection("videos").get().then((QuerySnapshot querySnapshot) => {
querySnapshot.docs.forEach((doc) {
// _controller.dispose();
videoUrl = doc["videoUrl"];
_controller = VideoPlayerController.network(videoUrl);
_initializeVideoPlayerFuture = _controller.initialize();
print(videoUrl);
})
});
// _controller = VideoPlayerController.network(videoUrl);
// _initializeVideoPlayerFuture = _controller.initialize();
super.initState();
}
#override
void dispose() {
_controller.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Flutter Video Player"),
),
body: FutureBuilder(
future: _initializeVideoPlayerFuture,
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
return Column(
children: [
AspectRatio(
aspectRatio: _controller.value.aspectRatio,
child: VideoPlayer(_controller),
),
],
);
} else {
return Center(child: CircularProgressIndicator());
}
},
),
floatingActionButton: FloatingActionButton(
onPressed: () {
setState(() {
if (_controller.value.isPlaying) {
_controller.pause();
} else {
_controller.play();
}
});
},
child: Icon(
_controller.value.isPlaying ? Icons.pause : Icons.play_arrow,
),
),
);
}
}
Try the following:
#override
void initState() {
super.initState();
firestore.collection("videos").get().then((QuerySnapshot querySnapshot) => {
querySnapshot.docs.forEach((doc) {
videoUrl = doc["videoUrl"];
_controller = VideoPlayerController.network(videoUrl);
_initializeVideoPlayerFuture = _controller.initialize().then((_) {
// Ensure the first frame is shown after the video is initialized, even before the play button has been pressed.
setState(() {});
});
});
});
}
Since initialize() is asynchronous, then you can use the method then which will get called when the future completes. Inside the callback, you can call setState() which will trigger a rebuild and notify the framework that the internal state of the widgets has changed .
https://pub.dev/packages/video_player
I updated to cloud_firestore 0.14.0
There's a few break changes:
BREAKING: The get data getter is now a data() method instead.
Before the update this is how I used the getter data
Before:
Future<String> getUsernameFromUserId(String userId) async {
return (await _userFirestoreCollection.document(userId).get()).data['screenName'];
}
This is how I use data now.. But doesn't seem to be working...
Now:
Future<String> getUsernameFromUserId(String userId) async {
return (await _userFirestoreCollection.document(userId).get()).data()['screenName'];
}
Starting from version cloud_firestore 0.14.0:
The method document() was changed and now you have to use doc() instead, therefore in your code you have to do the following:
Future<String> getUsernameFromUserId(String userId) async {
return (await _userFirestoreCollection.doc(userId).get()).data()["screenName"];
}
Example:
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: FirstRoute(title: 'First Route'),
);
}
}
class FirstRoute extends StatefulWidget {
FirstRoute({Key key, this.title}) : super(key: key);
final String title;
#override
_FirstRouteState createState() => _FirstRouteState();
}
class _FirstRouteState extends State<FirstRoute> {
#override
void initState() {
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("test"),
),
body: FutureBuilder(
future: getData(),
builder: (context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
return Column(
children: [
Container(
height: 27,
child: Text(
"Name: ${snapshot.data.data()['name']}",
overflow: TextOverflow.fade,
style: TextStyle(fontSize: 20),
),
),
],
);
} else if (snapshot.connectionState == ConnectionState.none) {
return Text("No data");
}
return CircularProgressIndicator();
},
));
}
Future<DocumentSnapshot> getData() async {
await Firebase.initializeApp();
return await FirebaseFirestore.instance
.collection("users")
.doc("docID")
.get();
}
}
Below you can see a code where I want to display data that I have collected from a registration form in Flutter.
the registration form push the data to a collection called " user " then some other documents data are pushed as:
name - email etc...
As you can see by XXXX I want that the data I retrieve from cloud firestore be shown into the widget:
Below the code:
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
class WelcomeScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.pink,
body: MainWelcome(),
);
}
}
class MainWelcome extends StatefulWidget {
#override
_MainWelcomeState createState() => _MainWelcomeState();
}
class _MainWelcomeState extends State<MainWelcome> {
final databaseReference = Firestore.instance;
Future<QuerySnapshot> getData() async {
return await Firestore.instance.collection("user").getDocuments();
}
#override
Widget build(BuildContext context) {
return FutureBuilder(
future: getData(),
builder: (context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
snapshot.data.documents.forEach((element) {
Center(
child: Text(
'Benvenuta ${element.data["name"]}',
style: TextStyle(fontSize: 20, color: Colors.white),
),
);
});
} else if (snapshot.connectionState == ConnectionState.none) {
return Text("No data");
}
return Center(child: CircularProgressIndicator());
},
);
}
}
You need to use a FutureBuilder widget to display the data in the widget tree:
Create a method that returns the data:
Future<QuerySnapshot> getData() async {
return await Firestore.instance
.collection("user")
.where("email", isEqualTo: "email_here")
.getDocuments();
}
Then inside the build() method do the following:
FutureBuilder(
future: getData(),
builder: (context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
return ListView.builder(
shrinkWrap: true,
itemCount: snapshot.data.documents.length,
itemBuilder: (BuildContext context, int index) {
return ListTile(
contentPadding: EdgeInsets.all(8.0),
title:
Text(snapshot.data.documents[index].data["name"]),
);
});
} else if (snapshot.connectionState == ConnectionState.none) {
return Text("No data");
}
return CircularProgressIndicator();
},
),
I have seen similar questions and answers being solved with the StreamBuilder widget.
In my case when I am implementing it my code does not await to fetch the data and just moves on (in my case, the app jumps to the next page). Thus, do I need the build a StreamBuilder Widget or is there a simple method that could work and fetch the data in realtime?
I noticed that I did not use async* with the asterisc but if I do so, then the authentication is not working.
Clarification:
The code does not enter the following lines:
if (!snapshot.hasData)
return new Text('Loading...');
return new Text(
snapshot.data.data['name']
);
Also the print(test); statement prints the following:
StreamBuilder<DocumentSnapshot>
Here is the whole part:
onPressed: () async {
setState(() {
showSpinner = true;
});
try {
LoginScreen.user =
await _auth.signInWithEmailAndPassword(
email: email, password: password);
if (LoginScreen.user != null) {
// get the users data and save them
if (LoginScreen.user.user.uid !=
'IDVwQXAsZas213Va0OIH2IsoU5asdaTfraBJ2') {
Widget test = await StreamBuilder<DocumentSnapshot>(
stream: _firestore
.collection('Employees')
.document(LoginScreen.user.user.uid)
.snapshots(),
builder: (BuildContext context,
AsyncSnapshot<DocumentSnapshot> snapshot) {
if (!snapshot.hasData)
return new Text('Loading...');
return new Text(
snapshot.data.data['name']
);
},
);
print(test);
Navigator.pushReplacementNamed(
context, TabCreator.screenId);
} else {
}
}
} catch (e) {
print(e);
// when getting an erro stop spinner
setState(() {
showSpinner = false;
});
}
}
Update:
I created a new standard flutter project in order to see if there was something else within my code that was messing the StreamBuilder. I am still getting no output.
On a side note when I am implementing the following code within the onPressed method I am getting the wanted result:
Alternative Solution:
onPressed: () {
DocumentReference documentReference = await Firestore.instance
.collection('Employees')
.document('8nss0gppzNfOBMuRz9H44dv7gSd2');
documentReference.snapshots().listen((datasnapshot) {
if (datasnapshot.exists) {
print(datasnapshot.data['name'].toString());
} else {
print('Error!');
}
});
}
Here is the implemented StreamBuilder implemented in the standard Flutter project:
import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final _auth = FirebaseAuth.instance;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'Testing',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
// DocumentReference documentReference = await Firestore.instance
// .collection('Employees')
// .document('8nss0gppzNfOBMuRz9H44dv7gSd2');
// documentReference.snapshots().listen((datasnapshot) {
// if (datasnapshot.exists) {
// print(datasnapshot.data['name'].toString());
// } else {
// print('Error!');
// }
// });
StreamBuilder<DocumentSnapshot>(
stream: Firestore.instance
.collection('Employees')
.document('8nss0gppzNfOBMuRz9H44dv7gSd2')
.snapshots(),
builder: (BuildContext context,
AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.hasError)
return new Text('Error: ${snapshot.error}');
switch (snapshot.connectionState) {
case ConnectionState.waiting:
return new Text('Loading...');
default:
return new Text(snapshot.data.data['name']);
}
},
);
},
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
Change your code to the following:
builder: : (BuildContext context,
AsyncSnapshot<DocumentSnapshot> snapshot) {
if (!snapshot.hasData){
return new Text('Loading...');
}
else{
print(snapshot);
Navigator.pushReplacementNamed(
context, TabCreator.screenId);
}
Add an else block so when you have data it will enter the else and navigate to the page.
Also you need to use the StreamBuilder inside the build method not inside the onPressed function which is used to handle data processing. Example you can do the following:
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
bool visible = false;
final firestoreInstance = Firestore.instance;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
Visibility(
child: StreamBuilder<DocumentSnapshot>(
stream: Firestore.instance
.collection('users')
.document('FIJbBBiplAGorYzdtUQF')
.snapshots(),
builder: (BuildContext context,
AsyncSnapshot<DocumentSnapshot> snapshot) {
print(snapshot);
if (snapshot.hasError)
return new Text('Error: ${snapshot.error}');
else if (snapshot.hasData) {
print(snapshot.data.data);
return new Text(snapshot.data.data["age"].toString());
}
return new CircularProgressIndicator();
},
),
visible: visible,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
setState(() {
visible = true;
});
},
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
So here I also use the Visibility() widget to hide it, but when FAB button is clicked the data from firestore will appear.