FutureBuilder in flutter building app again and again? - flutter

Question

what I am trying to do is check if user is logged in already or not. there is a futurebuilder inside consumer which is notifying listeners. check code:
#override
Widget build(BuildContext context) {
return MultiProvider(
providers: [
ChangeNotifierProvider.value(
value: Auth(),
)
],
child: Consumer<Auth>(
builder: (ctx, auth, _) {
print('making it again and again');
return MaterialApp(
title: 'MY app',
theme: ThemeData(
primarySwatch: Colors.blue,
accentColor: Colors.deepOrange,
),
home: auth.isAuth
? FirstScreen()
: FutureBuilder(
future: auth.tryAutoLogin(), //inside this function there is notifylisteners()
builder: (ctx, authResultSnapShot) =>
authResultSnapShot.connectionState ==
ConnectionState.waiting
? SplashScreen()
: AuthScreen(),
));
},
),
);
}
What I get:
this is rebuilding the app again and again. tryautologin is called repeatedly.
What I want:
check for is a user logged in only once the app is started.
Future<bool> tryAutoLogin() async {
final prefs = await SharedPreferences.getInstance();
if (!prefs.containsKey('userData')) {
return false;
}
final extractedUserData = json.decode(prefs.getString('userData'));
final expiryDate = DateTime.parse(extractedUserData['expiryDate']);
_accessToken = extractedUserData['accessToken'];
_refreshToken = extractedUserData['refreshToken'];
print(extractedUserData['userId']);
_userId = extractedUserData['userId'];
if (expiryDate.isBefore(DateTime.now())) { //for now this if statement is not running
try {
await _getAccessToken();
} catch (error) {
return false;
}
}
print('tryautologin');
notifyListeners();
_autoGetAccessToken(); //this function doesn't have any notifylisteners
return true;
}
edited:
String get accessToken {
if (_expiryDate != null &&
_expiryDate.isAfter(DateTime.now()) &&
_accessToken != null) {
return _accessToken;
}
return null;
}
bool get isAuth {
print(accessToken != null);
return accessToken != null;
}

Answer 1

Even the question is old quite a bit of time, this answer will help another. I have faced the problem also. this happens when you use a future builder inside a consumer. it is rebuilding again and again infinitely. So, instead of the future builder try using an if-else statement.
child: Consumer<Auth>(
builder: (ctx, auth, _) {
//Sizedbox() used for nullsafety
Widget child = SizedBox();
if (auth.isAuth) {
child = FirstScreen();
} else if (!auth.triedAutoLogin) {
auth.tryAutoLogin();
child = SplashScreen();
} else {
child = AuthScreen();
}
return MaterialApp(
title: 'MY app',
theme: ThemeData(
primarySwatch: Colors.blue,
accentColor: Colors.deepOrange,
),
home: child,
);
},
),
inside Auth class keep a boolean variable like triedAutoLogin to keep track.