[AngularFire2] Building an Authentication Observable Data Service

After successfully login, we want something help to check whether user has already login or not. And we will use Observable to do that.

Create AuthInfo.ts:

export class AuthInfo {
  constructor(private uid$: string){

  }

  isLoggedIn() {
    return !!this.uid$;
  }
}

The class is very simple, accpets an uid which return from FirebaseAuth, and a method to check whether id is set already.

TO user Observable to handle the data:

AuthService.ts:

  static UNKNOW_USER = new AuthInfo(null); // Create a default unknow user
  public authInfo$: BehaviorSubject<AuthInfo> = new BehaviorSubject<AuthInfo>(AuthService.UNKNOW_USER); // We user BehaviorSubject to to conver to Observable, Behavior Subject already needs a default value, so we can repersent logout status by using default value

  login(email, password) {

    return this.fromFirebaseAuthPromise(this.auth$.login({
      email, password
    },{
      method: AuthMethods.Password,
      provider: AuthProviders.Password
    }));
  }

  fromFirebaseAuthPromise(promise) {
    const subject = new Subject<any>();

    promise.then((res) => {
      const uid = this.auth$.getAuth().uid;
      const authInfo = new AuthInfo(uid);
      this.authInfo$.next(authInfo);
      subject.next(res);
      subject.complete();
    }, err => {
      this.authInfo$.error(err);
      subject.error(err);
      subject.complete();
    });

    return subject.asObservable();
  }

Everytime,we successfully login, will emit a uid. 

So to show / hide show content based on 'authInfo$', we can do:

      <md-list-item>
        <a
          *ngIf="authInfo$.isLoggedIn()"
          [routerLink]="['/heros', {outlets: {'wiki': null}}]"
          routerLinkActive="active"
          [routerLinkActiveOptions]="{exact: true}"
        >Heros</a>
      </md-list-item>

  authInfo$;
  constructor(private auth: AuthService){
      this.auth.authInfo$.subscribe(
        res => {
          this.authInfo$ = res;
        }
      )
  }