Access Google Sign-In username globally

Question

I have a problem with Firebase Auth in flutter, more specifically the user.displayName query. I use mandatory Google Sign In at the first screen of my app, so I can guarantee that on all subsequent screens the user has a name and a userId associated with him.

Every time I want to access the username however, all I do right now is essentially authenticate the user again with:

GoogleSignInAccount googleUser = await googleSignIn.signInSilently();
GoogleSignInAuthentication googleAuth = await googleUser.authentication;
FirebaseUser user = await auth.signInWithGoogle(
  accessToken: googleAuth.accessToken,
  idToken: googleAuth.idToken,
);
futureId = user.uid;

print("signed in " + user.displayName);
return user.displayName;

which obviously takes up unnecessary time and bandwidth.

Is there another way of doing that, since the user has already signed in once before? Could I maybe access the userdata that gets stored by Firebase Auth for use in other Firebase products (like Firestore)?

Solution

FirebaseAuth has an async method called currentUser that can be used to access the currently authenticated user.

dummy example:

class SomePage extends StatefulWidget {
  @override
  _SomePageState createState() => new _SomePageState();
}

class _SomePageState extends State<SomePage> {
  String _userName = "...";
  _getUserAuth(){
    FirebaseAuth.instance.currentUser().then((user){
      setState((){this._userName= user.displayName;}); 
    });
    print(this._userName);
  }
  @override
  Widget build(BuildContext context) {
    return new Center(
      child: new FlatButton(
        child: new Text(this._userName),
        onPressed: _getUserAuth,
      ),
    );
  }
}

Comments

[stefanmuke]

Thanks a lot for your answer! While the code seem to be correct, for me the function still returns null as the current username. This should theoretically not be possible since I use Firestore in the same app that is configured to require authentication on read. Do you know what could be the problem here?

[Shady Aziza]

It is working just fine with me, maybe show me how are you wiring things up and I will try to help