Is there any error in the try-catch exception handling below?-CodePudding

I tried to handle an exception while a user is trying to login after being authenticated by firebase. But this try-catch is not working in my flutter project.

Can someone let me know where did i go wrong? I have attached my code below.

Thank you in advance.

class AuthService {
  //Creating an instance of firebase.
  final auth.FirebaseAuth _firebaseAuth = auth.FirebaseAuth.instance;

  User? _userFromFirebase(auth.User? user) {
    if (user == null) {
      return null;
    }
    return User(user.uid, user.email);
  }

  Stream<User?>? get user {
    return _firebaseAuth.authStateChanges().map(_userFromFirebase);
  }

  Future<User?> signInWithEmailAndPassword(
    String email,
    String password,
  ) async {
    try {
      final credential = await _firebaseAuth.signInWithEmailAndPassword(
          email: email, password: password);

      return _userFromFirebase(credential.user);
    } on Exception catch (_, e) {
      //I want to display a toast message if the login fails here. 
      print(e);
    }
  }

  Future<void> signOut() async {
    return await _firebaseAuth.signOut();
  }
}

CodePudding user response：

In your try-catch block you are catching Exception types, but Firebase Authentication has its own exception type, FirebaseAuthException.

For possible error codes for this specific sign-in see here, but there are others as well.

Check the following code:

try {
  final credential = await _firebaseAuth.signInWithEmailAndPassword(
    email: email, password: password);
  return _userFromFirebase(credential.user);
} on FirebaseAuthException catch (e) {
  // here you will have the different error codes in `e.code`
  // for example `invalid-email` or `wrong-password`
}

It is up to you how do you handle these errors. You can return the error code for example and handle it from where you call this function (as h8moss suggested in comment).

And keep in mind that there are other possible reasons for a sign-in to fail than FirebaseAuthException. For example network connection can be down. So a more complete solution to catch other errors as well would be something like:

try {
  // sign in
} on FirebaseAuthException catch (e) {
  // handle Firebase Authentication exceptions
} catch (e) {
  // handle other exceptions
}