Home screen showing null future builder in firebaseAuth Flutter - firebase

Question

I am currently trying to get the current user state from FirebaseAuth and switch between home screen if user didn't logged out or splash screen if user is logged out. User registration and login are both successful and registered in firestore database. But everytime i closes the application from my phone and re opens, the MediaQuery.of(context) width has a null value and shows an error.
But the bottom navigation bar is still showing. It works when i rebuild the app and login again, it brings me to the home screen. It only occurs when i close and re open the app.
import 'package:country_code_picker/country_localizations.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'routes.dart';
import 'package:screens/home/home_screen.dart';
import 'package:screens/splash/splash_screen.dart';
import 'constants.dart';
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
runApp(MyApp());
}
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
supportedLocales: [Locale('en', 'US')],
localizationsDelegates: [CountryLocalizations.delegate],
title: 'App',
theme: theme(),
routes: routes,
home: LandingPage(),
);
}
}
class LandingPage extends StatelessWidget {
const LandingPage({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
final Future<FirebaseApp> _init = Firebase.initializeApp();
return FutureBuilder(
future: _init,
builder: (context, snapshot) {
if (snapshot.hasError) {
return Scaffold(
body: Center(
child: Text("Error: ${snapshot.error}"),
),
);
}
if (snapshot.connectionState == ConnectionState.done) {
return StreamBuilder(
stream: FirebaseAuth.instance.authStateChanges(),
builder: (context, streamSnapshot) {
if (streamSnapshot.hasError) {
return Scaffold(
body: Center(
child: Text("Error: ${streamSnapshot.error}"),
),
);
}
if (streamSnapshot.connectionState == ConnectionState.active) {
print(streamSnapshot.data.toString());
if (streamSnapshot.data == null) {
return SplashScreen();
} else {
return HomeScreen();
}
}
return Scaffold(
body: Center(
child: CircularProgressIndicator(
backgroundColor: Colors.white,
color: kPrimaryColor,
strokeWidth: 3,
),
),
);
},
);
}
return Scaffold(
body: Center(
child: CircularProgressIndicator(
backgroundColor: Colors.white,
color: kPrimaryColor,
strokeWidth: 3,
),
),
);
},
);
}
}
Maybe i thought its a problem with the future builder or stream builder? Any of you have a solution for this problem or another way to implement it.
Launching lib/main.dart on STK L21 in debug mode...
✓ Built build/app/outputs/flutter-apk/app-debug.apk.
Connecting to VM Service at ws://127.0.0.1:33019/yIPGCqY2gwY=/ws
I/flutter ( 4249): locale.languageCode: en
D/AwareBitmapCacher( 4249): handleInit switch not opened pid=4249
I/flutter ( 4249): User(displayName: , email: rohanbhautoo#gmail.com, emailVerified: false, isAnonymous: false, metadata: UserMetadata(creationTime: 2021-06-10 08:20:44.583, lastSignInTime: 2021-06-10 15:50:23.573), phoneNumber: , photoURL: null, providerData, [UserInfo(displayName: , email: rohanbhautoo#gmail.com, phoneNumber: , photoURL: null, providerId: password, uid: rohanbhautoo#gmail.com)], refreshToken: , tenantId: null, uid: yviaYOJ5ziayFQhvhvemB3MjkPr1)
════════ Exception caught by widgets library ═══════════════════════════════════
The following _CastError was thrown building Body(dirty):
Null check operator used on a null value
The relevant error-causing widget was
Body
When the exception was thrown, this was the stack
#0 getProportionateScreenWidth
#1 Body.build
#2 StatelessElement.build
#3 ComponentElement.performRebuild
#4 Element.rebuild
...
════════════════════════════════════════════════════════════════════════════════
Size_config.dart
import 'package:flutter/material.dart';
class SizeConfig {
static MediaQueryData? _mediaQueryData;
static double? screenWidth;
static double? screenHeight;
static double? defaultSize;
static Orientation? orientation;
void init(BuildContext context) {
_mediaQueryData = MediaQuery.of(context);
screenWidth = _mediaQueryData!.size.width;
screenHeight = _mediaQueryData!.size.height;
orientation = _mediaQueryData!.orientation;
}
}
// Proportionate height per screen size
double getProportionateScreenHeight(double inputHeight) {
double? screenHeight = SizeConfig.screenHeight;
return (inputHeight / 812.0) * screenHeight!;
}
// Proportionate width per screen size
double getProportionateScreenWidth(double inputWidth) {
double? screenWidth = SizeConfig.screenWidth;
return (inputWidth / 375.0) * screenWidth!;
}
The stacktrace line for #0 is return (inputWidth / 375.0) * screenWidth!; It is showing that im using a null check on screenWidth!.

Answer 1

I don't see where you actually call SizeConfig().init(context) ?
Nothing gets defined for you until that happens at the top of your project.

Answer 2

I guess the culprit is this line:
print(streamSnapshot.data.toString());
You are actually checking that streamSnapshot.data is null on the next line:
print(streamSnapshot.data.toString());
if (streamSnapshot.data == null) {
return SplashScreen();
} else {
return HomeScreen();
}