Angular Firebase Auth – Anonymous Authentication with AngularFire2 v4

Anonymous authentication uses only a userID to login without registration. Once signing out, user will not be able to log back in. In this tutorial, we’re gonna look at way to implement Anonymous authentication with AngularFire2 v4.

Related Post:
How to integrate Firebase with Angular 4

More Practice:
Angular 4 Firebase Auth – Email/Password Authentication with AngularFire2 v4

I. Technology

– Angular 4
– AngularFire2 4.0

II. Overview

We will build an Angular 4 App that allows user login anonymously:

II. How to do

1. Set up the Firebase Project & Install AngularFire2

Please visit this post to know step by step.

2. Enable Firebase Auth for Anonymous

Go to your Project on Firebase Console -> Authentication tab -> SIGN-IN METHOD -> enable Anonymous:

3. Auth Service

import {AngularFireAuth} from 'angularfire2/auth';

@Injectable()
export class AuthService {

  authState: any = null;

  constructor(private afAuth: AngularFireAuth) {
    this.afAuth.authState.subscribe((auth) => {
      this.authState = auth
    });
  }

  get isUserAnonymousLoggedIn(): boolean {
    return (this.authState !== null) ? this.authState.isAnonymous : false
  }

  get currentUserId(): string {
    return (this.authState !== null) ? this.authState.uid : '';
  }

  anonymousLogin() {
    return this.afAuth.auth.signInAnonymously()
      .then((user) => {
        this.authState = user
      })
      .catch(error => console.log(error));
  }

  signOut(): void {
    this.afAuth.auth.signOut();
  }
}

– We subscribe to the AngularFire auth observable that returns a FirebaseAuthState object. This object is null when logging out, and contains useful User Information (UID, Display Name, Photo URL…) when logging in.
– We use:
+ AngularFireAuth.auth.signInAnonymously() to log in.
+ AngularFireAuth.auth.signOut() to log out.

4. App Module

import {AngularFireModule} from 'angularfire2';
import {AngularFireAuthModule} from 'angularfire2/auth';

import {AuthService} from './auth/auth.service';

@NgModule({
  // ...
  imports: [
    AngularFireModule.initializeApp(environment.firebase),
    AngularFireAuthModule
  ],
  providers: [AuthService],
  // ...
})

III. Practice

1. Project structure

2. App Module

import {environment} from '../environments/environment';
import {BrowserModule} from '@angular/platform-browser';
import {NgModule} from '@angular/core';
import {AppRoutingModule} from './app-routing.module';

import {AngularFireModule} from 'angularfire2';
import {AngularFireAuthModule} from 'angularfire2/auth';

import {AuthService} from './auth/auth.service';

import {AppComponent} from './app.component';
import {UserLoginComponent} from './auth/user-login/user-login.component';
import {UserInfoComponent} from './auth/user-info/user-info.component';

@NgModule({
  declarations: [
    AppComponent,
    UserLoginComponent,
    UserInfoComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    AngularFireModule.initializeApp(environment.firebase),
    AngularFireAuthModule
  ],
  providers: [AuthService],
  bootstrap: [AppComponent]
})
export class AppModule {}

3. Auth Service

import {Injectable} from '@angular/core';
import {Router} from '@angular/router';
import {AngularFireAuth} from 'angularfire2/auth';

@Injectable()
export class AuthService {

  authState: any = null;

  constructor(private afAuth: AngularFireAuth, private router: Router) {
    this.afAuth.authState.subscribe((auth) => {
      this.authState = auth
    });
  }

  get isUserAnonymousLoggedIn(): boolean {
    return (this.authState !== null) ? this.authState.isAnonymous : false
  }

  get currentUserId(): string {
    return (this.authState !== null) ? this.authState.uid : '';
  }

  anonymousLogin() {
    return this.afAuth.auth.signInAnonymously()
      .then((user) => {
        this.authState = user
      })
      .catch(error => console.log(error));
  }

  signOut(): void {
    this.afAuth.auth.signOut();
    this.router.navigate(['/'])
  }
}

4. Components

4.1 User Login Component

user-login.component.ts

import {Component, OnInit} from '@angular/core';
import {Router} from '@angular/router';
import {AuthService} from '../auth.service';

@Component({
  selector: 'user-login',
  templateUrl: './user-login.component.html',
  styleUrls: ['./user-login.component.css']
})
export class UserLoginComponent implements OnInit {

  constructor(public authService: AuthService, private router: Router) {}

  ngOnInit() {
  }

  signInAnonymously() {
    this.authService.anonymousLogin()
      .then(() => this.router.navigate(['/']));
  }
}

user-login.component.html

<div *ngIf="!authService.isUserAnonymousLoggedIn">
	<button (click)="signInAnonymously()">Login</button>
</div>

4.2 User Info Component

user-info.component.ts

import {Component, OnInit} from '@angular/core';
import {AuthService} from '../auth.service';

@Component({
  selector: 'user-info',
  templateUrl: './user-info.component.html',
  styleUrls: ['./user-info.component.css']
})
export class UserInfoComponent implements OnInit {

  constructor(public authService: AuthService) {}

  ngOnInit() {
  }

  logout() {
    this.authService.signOut();
  }

}

user-info.component.html

<div *ngIf="authService.isUserAnonymousLoggedIn">
	<h5 class="text-primary">User Information</h5>
	<h4>
		<strong>UID:</strong> {{ authService.currentUserId }}
	</h4>
	<button class="button" (click)="logout()">Logout</button>
</div>

5. App Routing Module

app-routing.module.ts

import {NgModule} from '@angular/core';
import {RouterModule, Routes} from '@angular/router';

import { UserLoginComponent } from './auth/user-login/user-login.component';

const routes: Routes = [
  {path: '', redirectTo: 'login', pathMatch: 'full'},
  {path: 'login', component: UserLoginComponent},
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})

export class AppRoutingModule {}

6. App Component

app.component.ts

import {Component} from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})

export class AppComponent {
  title = 'JavaSampleApproach';
  description = 'Angular4-Firebase Demo';
}

app.component.html

<div class="container">
	<div style="color: blue; margin-bottom:20px">
		<h1>{{title}}</h1>
		<h3>{{description}}</h3>
	</div>

	<user-info></user-info>

	<router-outlet></router-outlet>
</div>

7. Check Result

Run the App, login and log out several times:

Firebase Console:

IV. Source Code

Angular4FirebaseAuth-anonymous

Last updated on March 18, 2021.