Unable to print / get the logged in user's username in Flutter

Question

I'll preface this by saying that I'm pretty new to Flutter and I'm building a Messenger / Chat app. I'm using Firebase to register the user, using Email/Password and I'm doing that successfully.

This is my SignIn.dart

        import 'package:chat_app/helper/helperfunctions.dart';
import 'package:chat_app/services/auth.dart';
import 'package:chat_app/services/database.dart';
import 'package:chat_app/widgets/widgets.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

import 'chatRoomsScreen.dart';

class SignIn extends StatefulWidget {

  late final Function toggle;
  SignIn(this.toggle);

  @override
  _SignInState createState() => _SignInState();
}

class _SignInState extends State<SignIn> {

  final formKey = GlobalKey<FormState>();
  TextEditingController emailTextEditingController = new TextEditingController();
  TextEditingController passwordTextEditingController = new TextEditingController();
  AuthMethods authMethods = new AuthMethods();
  DatabaseMethods databaseMethods = new DatabaseMethods();

  bool isLoading = false;
  late QuerySnapshot<Map<String, dynamic>>? snapShotUserInfo;

  signIn() async {
    if (formKey.currentState!.validate()) {

      HelperFunctions.saveUserEmailSharedPreference(emailTextEditingController.text);
      setState(() {
        isLoading = true;
      });

      databaseMethods.getUserByUserEmail(emailTextEditingController.text).then((val) {
        snapShotUserInfo = val;
        HelperFunctions
            .saveUserNameSharedPreference(snapShotUserInfo?.docs[0].data()["name"]);
        print("${snapShotUserInfo?.docs[0].data()["name"]} is my name");
      });


      authMethods.signInWithEmailAndPassword(emailTextEditingController.text, passwordTextEditingController.text)
      .then((val) {
        if (val != null) {

          HelperFunctions.saveUserLoggedInSharedPreference(true);
          Navigator.pushReplacement(context,
              MaterialPageRoute(
                  builder: (context) => ChatRoom())
          );
        }
      });

    }
  }


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: appBarMain(context),
      body: SingleChildScrollView(
        child: Container(
          padding: EdgeInsets.fromLTRB(0, 80, 0, 0),
          alignment: Alignment.bottomCenter,
          child: Container(
            padding: EdgeInsets.symmetric(
              horizontal: 24.0
            ),
            child: Form(
              key: formKey,
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  TextFormField(
                      validator: (val) {
                        return RegExp(
                            r"^[a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~]+@[a-zA-Z0-9]+\.[a-zA-Z]+")
                            .hasMatch(val!)
                            ? null
                            : "Please Enter Correct Email";
                      },
                    controller: emailTextEditingController,
                    style: simpleTextStyle(),
                    decoration: textFieldInputDecoration("email")
                  ),
                  TextFormField(
                      validator: (val) {
                        return val!.length > 6 ? null : "Provide a longer password!";
                      },
                    controller: passwordTextEditingController,
                      style: simpleTextStyle(),
                    obscureText: true,
                    decoration: textFieldInputDecoration("password")
                  ),
                  SizedBox(height: 12),
                  Container(
                    alignment: Alignment.centerRight,
                    padding: EdgeInsets.symmetric(
                      horizontal: 16,
                      vertical: 8,
                    ),
                    child: Text("Forgot Password?",
                    style: simpleTextStyle(),),
                  ),
                  SizedBox(height: 8),
                  GestureDetector(
                    onTap: () {
                      signIn();
                    },
                    child: Container(
                      alignment: Alignment.center,
                      width: MediaQuery.of(context).size.width,
                      padding: EdgeInsets.symmetric(vertical: 20),
                      decoration: BoxDecoration(
                        borderRadius: BorderRadius.circular(30),
                        gradient: LinearGradient(
                          colors: [
                            Colors.amber,
                            Colors.amber
                          ]
                        )
                      ),
                      child: Text(
                          "Sign In",
                          style: TextStyle(
                              color: Colors.black,
                              fontSize: 16
                          )
                      ),
                    ),
                  ),
                  SizedBox(height: 16),
                  Container(
                    alignment: Alignment.center,
                    width: MediaQuery.of(context).size.width,
                    padding: EdgeInsets.symmetric(vertical: 20),
                    decoration: BoxDecoration(
                        borderRadius: BorderRadius.circular(30),
                        color: Colors.white,
                    ),
                    child: Text(
                        "Sign In with Google",
                        style: TextStyle(
                            color: Colors.black,
                            fontSize: 16
                        )
                    ),
                  ),
                  SizedBox(height: 16),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Text("Don't have account? ", style: mediumTextStyle()),
                      GestureDetector(
                        onTap: () {
                          widget.toggle();
                        },
                        child: Container(
                          padding: EdgeInsets.symmetric(vertical: 8),
                          child: Text("Register now!",style: TextStyle(
                            color: Colors.amber,
                            fontSize: 16,
                            decoration: TextDecoration.underline,
                          ),),
                        ),
                      ),
                    ],
                  ),
                  SizedBox(height: 50),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}

HelperFunctions.dart (using SharedPreferences package):

    import 'package:shared_preferences/shared_preferences.dart';

class HelperFunctions {

  static String sharedPreferenceUserLoggedInKey = "ISLOGGEDIN";
  static String sharedPreferenceUserNameKey = "USERNAMEKEY";
  static String sharedPreferenceUserEmailKey = "USEREMAILKEY";

  static Future<bool> saveUserLoggedInSharedPreference(bool isUserLoggedIn) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return await prefs.setBool(sharedPreferenceUserLoggedInKey, isUserLoggedIn);
  }

  static Future<bool> saveUserNameSharedPreference(String userName) async{
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return await prefs.setString(sharedPreferenceUserNameKey, userName);
  }

  /// ---

  static Future<bool> saveUserEmailSharedPreference(String userEmail) async{
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return await prefs.setString(sharedPreferenceUserEmailKey, userEmail);
  }

  static Future<bool?> getUserLoggedInSharedPreference() async{
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return prefs.getBool(sharedPreferenceUserLoggedInKey);
  }

  static Future<String?> getUserNameSharedPreference() async{
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return prefs.getString(sharedPreferenceUserNameKey);
  }

  static Future<String?> getUserEmailSharedPreference() async{
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return prefs.getString(sharedPreferenceUserEmailKey);
  }

}

DatebaseMethods.dart:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';

class DatabaseMethods {

  getUserByUsername(String username) async {
    return await FirebaseFirestore.instance.collection("users")
        .where("name", isEqualTo: username).get();
  }

  getUserByUserEmail(String userEmail) async {
    return await FirebaseFirestore.instance.collection("users")
        .where("name", isEqualTo: userEmail).get();
  }

  uploadUserInfo(userMap) {
    FirebaseFirestore.instance.collection("users").add(userMap);
  }

  createChatRoom(String chatRoomId, chatRoomMap) {
    FirebaseFirestore.instance.collection("ChatRoom")
        .doc(chatRoomId).set(chatRoomMap).catchError((e) {
          print(e.toString());
    });
  }
}

AuthMethods.dart:

    import 'package:firebase_auth/firebase_auth.dart';
import 'package:chat_app/modal/appUser.dart';
import 'package:firebase_core/firebase_core.dart';

class AuthMethods {
  final FirebaseAuth _auth = FirebaseAuth.instance;

  appUser? _userFromFirebaseUser(User user) {
    return user != null ? appUser(userId: user.uid) : null;
  }

  Future signInWithEmailAndPassword(String email, String password) async {
    try {
      UserCredential result = await _auth.signInWithEmailAndPassword(
          email: email, password: password);
      User? firebaseUser = result.user;
      return _userFromFirebaseUser(firebaseUser!);
    } catch (e) {
      print(e);
    }
  }

  Future signUpWithEmailAndPassword(String email, String password) async {
    try {
      UserCredential result = await _auth.createUserWithEmailAndPassword
        (email: email, password: password);
      User? firebaseUser = result.user;
      return _userFromFirebaseUser(firebaseUser!);
    } catch(e) {
      print(e.toString());
    }
  }

  Future resetPass(String email) async {
    try {
      return await _auth.sendPasswordResetEmail(email: email);
    } catch(e) {
      print(e.toString());
    }
  }

  Future signOut() async {
    try {
      return await _auth.signOut();
    } catch(e) {
      print(e.toString());
    }
  }


}

Everything else is working, hell - I'm even saving the email of the logged in users in the Firebase User Database, but I'm unable to fetch the username whenever I sign-in, what am I doing wrong? You can see that I've tried printing the username quite a few times (as I need it to proceed to Chat Rooms), what am I doing wrong here?

Answer 1

in getUserByUsername the return type is dynamic You need to specify the return type as Future<String> and await that value when you invoke the method.