What is Firebase Auth?

Sign users in with Firebase Auth.

What is FirebaseAuth?

FirebaseAuth is Firebase's authentication service; it provides user registration, sign-in, and session management under a single API. You access the singleton instance available everywhere via FirebaseAuth.instance. Through this instance you perform sign-in with email, phone, or Google methods.

final auth = FirebaseAuth.instance;
final user = auth.currentUser;

Session check with currentUser

You access the currently signed-in user with auth.currentUser. It returns a User object if a session is open, or null if not. You use this property to check the user's session status when the app starts.

final user = auth.currentUser;
if (user != null) {
  print(user.email);
}

Exercise Check the current user

Get the auth instance via FirebaseAuth.instance. Check currentUser; print 'yok' if there is no session, or the email if there is.

Show example solution

class User {
  final String email;
  User(this.email);
}

class FirebaseAuth {
  static final FirebaseAuth instance = FirebaseAuth._();
  FirebaseAuth._();
  User? get currentUser => null;
}

void main() {
  final auth = FirebaseAuth.instance;
  final user = auth.currentUser;
  print(user?.email ?? 'yok');
}

Test yourself

What does FirebaseAuth.instance return?
- A new User object
- An initialization settings object
- An error handling object
- A singleton FirebaseAuth instance across the app
Show answer

A singleton FirebaseAuth instance across the app — FirebaseAuth.instance returns the singleton FirebaseAuth instance accessible from anywhere in the app; it is not a new User or a settings object.

Access the singleton instance

final auth = ____;

Show answer

final auth = FirebaseAuth.instance;

FirebaseAuth parts

FirebaseAuth.instance

Singleton instance
currentUser

Signed-in user
FirebaseAuth

Authentication service
null

When no session

Next lesson: Email and password

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