How do you make a route guard with AngularFire2 wait for auth check

Question

I want my auth guard to wait until I get the auth back from firebase before it reroutes me. Currently, the auth guard check inits first.

I need to make it async in the canActivate, or only populate the canActivate after called.

auth.guard.ts

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

@Injectable()
export class AuthGuard implements CanActivate {
    constructor(private authService: AuthService) { 
        console.log(this.authService.isAuthenticated); // returns false, doesn't async
    }

  canActivate() {
      console.log(this.authService.isAuthenticated); // returns false
      return this.authService.isAuthenticated;
  }
}

auth.service.ts

...
import { AngularFire, 
    AuthProviders, 
    AuthMethods, 
    FirebaseListObservable, 
    FirebaseObjectObservable } from 'angularfire2';
...

@Injectable()
export class AuthService {
    isAuthenticated: boolean = false; 
    // the problem is setting it to a bool, need to async it (( but this was from official documentation and Pluralsight tuts__

    constructor(
        public af: AngularFire, 
        private _router: Router, 
        private _route: ActivatedRoute ) { 
           this.af.auth.subscribe((auth)=>{

               console.log('called after after auth guard');

               if (auth == null) {
                   this._router.navigate(['/login']);
               } else {
                   this.isAuthenticated = true;
               }
           }
       });
   }

So how can I make the AuthGuard's canActivate wait for an async boolean?

And how do I pass it to the AuthGuard's canActivate() function?

Answer 1

It was answer in this issue post on Github.

auth.service.ts:

@Injectable()
export class AuthService {

  private _user: firebase.User;

  constructor(public afAuth: AngularFireAuth, private db: AngularFireDatabase) {
    afAuth.authState.subscribe(user => this.user = user);  
  }

  get user(): firebase.User {
    return this._user;
  }

  set user(value: firebase.User) {
    this._user = value;
  }

  get authenticated(): boolean {
    return this._user !== null;
  }
}

auth.guard.ts:

@Injectable()
export class AuthGuard implements CanActivate {

  constructor(private auth: AuthService, private router: Router) {}

  canActivate(
    next: ActivatedRouteSnapshot,
    state: RouterStateSnapshot): Observable<boolean> | Promise<boolean> | boolean {
    return this.auth.afAuth.authState
            .take(1)
            .map(authState => !!authState)
            .do(authenticated => {
              if (!authenticated) {
                  this.router.navigate(['login']);
              }
            });
  }
}