get user data from uid in firebase database flutter

Question

Can you help me? I've only been learning Flutter for a few months and I want to get user data from Firebase and display the user profile. But it doesn't work, this is my code:

DatabaseReference _ref;

  var email, nama, noTelp;

  @override
  void initState() {
    // TODO: implement initState
    super.initState();



    final User usernya = _auth.currentUser;
    final String uid = usernya.uid;

    _ref = FirebaseDatabase.instance.reference().child('user').child(uid);

    email = _ref.child('email');
    nama = _ref.child('nama');
    noTelp = _ref.child('noTelp');
  }

And this code for user profiles:

Column(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: [
                              _ref == null
                                  ? Text(
                                      'Nama Pengguna',
                                      style: TextStyle(
                                          fontSize: 18,
                                          fontWeight: FontWeight.bold,
                                          color: Colors.white),
                                    )
                                  : Text(
                                      nama.toString(),
                                      style: TextStyle(
                                          fontSize: 18,
                                          fontWeight: FontWeight.bold,
                                          color: Colors.white),
                                    ),
                              Text(
                                email.toString(),
                                style: (TextStyle(color: Colors.white)),
                              ),
                              Text(noTelp.toString(),
                                  style: (TextStyle(color: Colors.white)))
                            ],
                          )

And I get output like this instance of 'Database Reference'

This is my user data in firebase:

And I got output like this:

Answer 1

You should call Firestore method get() to fetch data, then read the returned document from the callback.

FirebaseDatabase.instance.reference().child('user').child(uid).get().then((docSnapshot) {
    print(docSnapshot.data()["email"]); // print data to test
  });

Please find references here

Answer 2

It should look like that (with cloud firestore):

  // collection reference
  final CollectionReference _userCollection =
      Firestore.instance.collection('users');
  
  Future getUser(String uid) async {
    return await _userCollection.document(uid).snapshots().map((doc) {
      _userDataFromSnapshot(doc);
    });
  }
  
  // userData from snapshot
  UserData _userDataFromSnapshot(DocumentSnapshot snapshot) {
    return UserData(
      uid: uid,
      nickname: snapshot.data['nickname'],
    );
  }