What is Firebase Auth?
- Flutter course
- Advanced
- Lesson 16/69
- 4 min
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);
}Practice 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.
Starter code
class User {
final String email;
User(this.email);
}
class FirebaseAuth {
static final FirebaseAuth instance = FirebaseAuth._();
FirebaseAuth._();
User? get currentUser => null;
}
void main() {
// tekil örnek ile auth al
// mevcut kullanıcıyı kontrol et, yoksa 'yok' yazdır
}Sample 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');
}Expected output
yok
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does FirebaseAuth.instance return?
- A new User object
- An initialization settings object
- An error handling object
- A singleton FirebaseAuth instance across the app Correct answer
Explanation: FirebaseAuth.instance returns the singleton FirebaseAuth instance accessible from anywhere in the app; it is not a new User or a settings object.
2 Access the singleton instance
final auth = ____;final auth = FirebaseAuth.instance;Explanation: FirebaseAuth.instance gives the singleton instance accessible from anywhere in the app; it is not a constructor call.
3 FirebaseAuth parts
| Term | Meaning |
|---|---|
FirebaseAuth.instance |
Singleton instance |
currentUser |
Signed-in user |
FirebaseAuth |
Authentication service |
null |
When no session |