issue with flutter firebase login - firebase

Question

I recently made things work with the login/register module on my app but there are 2 things that are not working:
first when I register it's ok, I can see in my Firebase Console that the app is creating a new user so that's fine. However, when I try to log in with a user that doesn't exist it still makes me go to the homepage.
no idea how to make a persistent login, like someone who log in and someone who register when they close the app and then restart the app they should be able to keep the login and then logout if they want.
CAN ANYBODY HELP??
I leave here the code:
MAIN
import 'package:flutter/material.dart';
import 'package:sport_app/auth_screen.dart';
import 'package:sport_app/home_screen.dart';
import 'package:sport_app/intro_screen.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
inputDecorationTheme: InputDecorationTheme(
filled: true,
fillColor: Color(0xfff2f9fe),
enabledBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.grey[200]),
borderRadius: BorderRadius.circular(25),
),
focusedBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.grey[200]),
borderRadius: BorderRadius.circular(25),
),
disabledBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.grey[200]),
borderRadius: BorderRadius.circular(25),
),
),
),
home: IntroScreen(),
routes: {
'intro': (context) => IntroScreen(),
'home': (context) => HomeScreen(),
'login': (context) => AuthScreen(authType: AuthType.login),
'register': (context) => AuthScreen(authType: AuthType.register),
},
);
}
}
AUTH_PAGE
import 'package:flutter/material.dart';
import 'package:sport_app/auth_screen.dart';
import 'package:sport_app/auth.dart';
import 'package:sport_app/original_button.dart';
class AuthForm extends StatefulWidget {
final AuthType authType;
const AuthForm({Key key, #required this.authType}) : super(key: key);
#override
_AuthFormState createState() => _AuthFormState();
}
class _AuthFormState extends State<AuthForm> {
final _formKey = GlobalKey<FormState>();
String _email = '', _password = '';
AuthBase authBase = AuthBase();
#override
Widget build(BuildContext context) {
return Form(
key: _formKey,
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 50, vertical: 20),
child: Column(
children: <Widget>[
TextFormField(
decoration: InputDecoration(
labelText: 'Enter your email',
hintText: 'ex: test#gmail.com',
),
onChanged: (value) {
_email = value;
},
validator: (value) =>
value.isEmpty ? 'You must enter a valid email' : null,
),
SizedBox(height: 10),
TextFormField(
decoration: InputDecoration(
labelText: 'Enter your password',
),
obscureText: true,
onChanged: (value) {
_password = value;
},
validator: (value) => value.length <= 6
? 'Your password must be larger than 6 characters'
: null,
),
SizedBox(height: 20),
OriginalButton(
text: widget.authType == AuthType.login ? 'Login' : 'Register',
color: Colors.lightBlue,
textColor: Colors.white,
onPressed: () async {
if (_formKey.currentState.validate()) {
if (widget.authType == AuthType.login) {
await authBase.loginWithEmailAndPassword(_email, _password);
Navigator.of(context).pushReplacementNamed('home');
} else {
await authBase.registerWithEmailAndPassword(_email, _password);
Navigator.of(context).pushReplacementNamed('home');
}
// print(_email);
// print(_password);
}
},
),
SizedBox(height: 6),
FlatButton(
onPressed: () {
if (widget.authType == AuthType.login) {
Navigator.of(context).pushReplacementNamed('register');
print(widget.authType);
} else {
Navigator.of(context).pushReplacementNamed('login');
}
},
child: Text(
widget.authType == AuthType.login
? 'Don\'t have an account?'
: 'Already have an account?',
style: TextStyle(fontSize: 18, color: Colors.black54),
),
),
],
),
),
);
}
}
AUTHBASE
import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
class User {
final String uid;
User({#required this.uid});
}
class AuthBase {
User _userFromFirebase(FirebaseUser user) {
return user != null ? User(uid: user.uid) : null;
}
Future<void> registerWithEmailAndPassword(
String email, String password) async {
try {
final authResult = await FirebaseAuth.instance
.createUserWithEmailAndPassword(email: email, password: password);
return _userFromFirebase(authResult.user);
} catch (e) {
print(e.toString());
return null;
}
}
Future<void> loginWithEmailAndPassword(String email, String password) async {
try {
final authResult = await FirebaseAuth.instance
.signInWithEmailAndPassword(email: email, password: password);
return _userFromFirebase(authResult.user);
} catch (e) {
print(e.toString());
return null;
}
}
Future<void> logout() async {
await FirebaseAuth.instance.signOut();
}
}

Answer 1

UPDATE
You simply navigate to the homepage, even when the login has not completed successfully, becaus there is no condition logic. Do the navigation only in your authBase class, then you should be fine.
You need to import the FirebaseAuthException before you can use it. Then, you
Future<bool> loginWithEmailAndPassword(String email, String password) async {
try {
final authResult = await FirebaseAuth.instance
.signInWithEmailAndPassword(email: email, password: password);
if(authResult.user != null) { Navigator.of(context).pushReplacementNamed('home'); }
} on FirebaseAuthException catch (e) {
print(e.toString());
if(e.code == 'wrong-password') { Scaffold.of(context).showSnackBar(SnackBar(
content: Text("Wrong Password"),
)); }
else if (e.code == 'user-not-found') { Scaffold.of(context).showSnackBar(SnackBar(
content: Text("User not found"),
)); }
else if (e.code == 'invalid-email') { Scaffold.of(context).showSnackBar(SnackBar(
content: Text("Invalid E-Mail"),
)); }
return false;
}
}
and remove change your widget code to:
if (_formKey.currentState.validate()) {
if (widget.authType == AuthType.login) {
await authBase.loginWithEmailAndPassword(_email, _password);
} else {
await authBase.registerWithEmailAndPassword(_email, _password);
}
}
Second Problem:
You could try storing the login credentials in the storage (user flutter_secure_storage package for encryption) after the first login and then retrieve it on App startup to perform login like above
Here is a link for the package you should use to store the credentials
flutter_secure_storage