Flutter Firebase Authentication Event Handler And Hot Reloads
Tags: flutter, firebase, programming, tutorial
Published: 2022-11-10 07:22:15

Firebase is the ultimate Backend-as-a-Service (BaaS) app development platform. These extensively offer you complete hosted backend services that include cloud storage, machine learning, and many more. 

Google-backed application development software is helpful for easily giving Flutter Builders a completely new facility. Firebase offers the Flutter developers the complete attribute for developing Android, iOS as well as Flutter Web apps.

##What is the need For Flutter Firebase Authentication?

Google’s portable UI toolkit is helpful for crafting beautiful and natively compiled applications for the web, desktop, and mobile from a single codebase. Normally, Flutter works on the existing code especially used by almost every mobile application development company and developers. These are open-source and free-to-use attributes. Firebase Flutter offers better tools for

- Tracking analytics
- Reporting and fixing app crashes
- Product experiment
- Creating marketing

Flutter offers designers with providing better user experiences. Flutter is the top design idea of the decade known for its ability to turn into production code. These do not compromise mainly imposed by the typical frameworks, and they act as a unique productive prototyping tool. 

It also has CodePen support to share ideas even without any ideas. Below is the process for implementing the flutter app using the go router. These are added with the firebase authentication handler using the initiate() on the flutter App

```dart
@override
void initiate() {
appService = AppService(widget.sharedPreferences);
authService = AuthService();
authSubscription = authService.onAuthStateChange.listen(onAuthStateChange);
super.initState();
  }
```

The above process relies on the authservice class, and it is enabled with the constructor added along with them.

```dart
AuthService() {
authSubscription =
FirebaseAuth.instance.authStateChanges().listen((User? user) {
if (user == null) {
//appService.loginState = false;
print('User is currently signed out!');
_onAuthStateChange.add(false);
      } else {
//appService.loginState = true;
print('User is signed in!');
        _onAuthStateChange.add(true);
      }
    });
  }
```

##How To Use The Firebase Authentication?

Installing the Flutter Firebase event handler is a convenient option for getting Authentication on a wider number of aspects. When the Flutter Firebase is installed, then you can easily access the firebase_auth plugin by importing then with the Dart code – import ‘package:firebase_auth/firebase_auth.dart’. 

These are the perfect option for making the better Firebase Auth. It is a suitable option for initializing FlutterFire. For creating a new Firebase Auth, you can get with FirebaseAuth:

```
FirebaseAuthauth = FirebaseAuth.instance;
```

It allows interacting with Firebase Auth on the default Firebase App. These are used with installing FlutterFire on the platform. 

**When you are using the secondary Firebase App, then it is convenient for using the instance method:**

```dart
FirebaseApp secondary_app = Firebase.app('SecondaryApp');
FirebaseAuth auth = FirebaseAuth.instance(app: secondary app);
```

##Need For Firebase Auth:

The Firebase Auth assures making the complete method utilizing the better aspects for integrating the secure authentication on the new or even existing Flutter application. It is also quite efficient for making the authentication state user when they are logged in or even out. 

Flutter Firebase Authentication enables the high-end aspects of subscribing to the real-time via stream. These are called the stream offering the high-end aspects of the user’s current authentication state.

The process assures providing the subsequent events making the authentication state changes. There are 3 methods for extensively listening with authentication state changes:

`authStateChanges()`

For making the complete changes by calling the auth state changes() method, it includes the FirebaseAuth instance:

```dart
FirebaseAuth.instance
.authStateChanges()
.listen((User? user) {
if (user == null) {
print('User is currently signed out!');
    } else {
print('User is signed in!');
    }
  });
```

##What is Firebase Authentication Event Handler?

Firebase Authentication Events will be fired with the following occurs:

- When a user is signed in
- Right after listeners are registered
- When current users are signed out

Including the idTokenChanges() lets you easily improve the standard attributes to easily improve the Flutter firebase. Subscribe changes making the idTokenChanges() method in the FirebaseAuth instance:

```dart
FirebaseAuth.instance
.idTokenChanges()
.listen((User? user) {
if (user == null) {
print('User is currently signed out!');
    } else {
print('User is signed in!');
    }
  });
```

Events will be fired with the following occurring when the user is signed in. These are also involved when the current user is signed out. When there is a change in the current user’s token. The user signs in and re-authenticates after custom claims will be modified. It also includes the ID token issued containing all the latest claims. 

The existing user session will be getting the token ID with refreshing when the older token expires. ID token also forces refreshing by calling `FirebaseAuth.instance.currentUser.getIdTokenResult(true).` Firebase admin propagating with assessing custom claims on client
`userChanges()`
For subscribing with changes, it also involves with calling the userChanges() method for making the unique FirebaseAuth instance:

```dart
FirebaseAuth.instance
.userChanges()
.listen((User? user) {
if (user == null) {
print('User is currently signed out!');
    } else {
print('User is signed in!');
    }
  });
```

All the Events will be filed with maintaining the occurrence when the user is signed in or signed out. It also involves with there is a change in the current user’s token, so they provide you better method providing with FirebaseAuth.instance.currentUser is called:

```dart
reload()
unlink()
updateEmail()
updatePassword()
updatePhoneNumber()
updateProfile()
```

##Persisting Authentication State#:

Firebase SDKs are available with the platforms providing you with complete support out of the box. This ensures that the user’s authentication state persists across the app for reloading and restarting. 

Native platforms like Android & are involved without configurable attributes along with the user’s authentication state. These persist with on-device between the app restarts, so they are also involved with making complete attributes. 

The user clears apps cached data through the device settings, especially wipes on existing state stored. The user’s authentication state will be stored with local storage in the web platform. 

It is easier to change the default behavior on the persistent authentication state for the current session. These also involved configuring settings with the calling setPersistence() method.

```dart
authStateChanges()
userChanges()
idTokenChanges()
```

These will not fire when you update the user profile through firebase admin SDK implementation. It is convenient for forcing reloading following FirebaseAuth.instance.currentUser.reload(). These are suitable options for retrieving the latest User profile. 

When you disable or delete a User through your own firebase admin SDK implementation, it is a suitable option for gaining a better solution. This causes user-disabled or even maintaining user-not-found exception catches and handles in your app code.

```dart
User?user = FirebaseAuth.instance.currentUser;
if (user != null && !user.emailVerified) {
varactionCodeSettings = ActionCodeSettings(
url: 'https://www.example.com/?email=${user.email}',
dynamicLinkDomain: 'example.page.link',
androidPackageName: 'com.example.android',
androidInstallApp: true,
androidMinimumVersion: '12',
iOSBundleId: 'com.example.ios',
handleCodeInApp: true,
  );
awaituser.sendEmailVerification(actionCodeSettings);
}
```

##Conclusion:

Flutter Firebase Authentication event handler illustrates how to handle the verification process that opens in a mobile app first as a Firebase Dynamic Link. Firebase also provides a wide number of ways to sign users into the application.

Moreover, It brings you a better option for easily making Flutter Firebase Authentication event handlers along with hot reloads.

##Frequently Asked Questions (FAQs)


###1. What other options in Flutter do you have to implement authentication?

Firebase authentication offers backend services, ready-made UI libraries, and easy-to-use SDKs which will authenticate users to your app. It supports authentication with strong passwords, phone numbers, and well-known federated identity providers such as Google, Twitter, and more.

###2. Where are the logs of Flutter stored?

Logs are stored in the database and can be exported as a zip file. After that, it is uploaded to a server or used locally to identify and debug issues. Hence, the logs are filtered and sorted quickly based on the valuable filters available.

###3. Why is Firebase the excellent option for Flutter development?

It is the Faster time to market. The Firebase real-time database, ready-made authentication option, and the in-built widgets of Flutter also use the single code for iOS and Android development. Hence, it makes the development procedure faster and maintains the safety and performance of applications.