Getting null value to a variable after async method flutter

Question

I'm getting null value in flutter build method for this code.

  String userEmail;
  var data;
  String userName;
  @override
  void initState(){
      setState(() {
        getUserName();
        print(userName);
      });
    super.initState();
  }

  void getUserName() async {
    MyFirebaseAuth myFirebaseAuth = MyFirebaseAuth();
    userEmail =await myFirebaseAuth.getUser();
    if (userEmail == null){
      print("no user");
    }
    else{
      data =await fb.firestore().collection('users').doc(userEmail).get().then((onValue){
        return onValue.data();
      });
      print(data);
      print(data['name']);
      userName = data['name'];
      print("Username is $userName");
    }
  }

output is

Performing hot restart...

Restarted application in 759ms. null {entries: 3, name: xmr} vraj Username is xmr

can you please show us MyFirebaseAuth ? and try to remove setState from the initstate — Boby
– Boby, Commented Dec 1, 2019 at 5:44

Khadga shrestha · Accepted Answer · 2019-12-01 05:46:58Z

1

The getUserName is future so the method should be

Future<void>getUserName() async {
MyFirebaseAuth myFirebaseAuth = MyFirebaseAuth();
userEmail =await myFirebaseAuth.getUser();
if (userEmail == null){
  print("no user");
}
else{
  data =await fb.firestore().collection('users').doc(userEmail).get().then((onValue){
    return onValue.data();
  });
  print(data);
  print(data['name']);
  userName = data['name'];
  print("Username is $userName");
}
}

And also make sure to use setState inside the getUserName() instead of initState

answered Dec 1, 2019 at 5:46

Khadga shrestha

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