Angular 2+ wait for method / observable to complete

Question

I need to check te back-end for authentication status, however te code completes before te observable return is finished. Which would result in an undifined.

Answer 1

Solved the issue with async / await and promise

The LoginService first import toPromise:

import 'rxjs/add/operator/toPromise';

Then created an async method in the LoginService

  async isAuthenticated(){
     const response = await this.http.get('/login/authenticated').toPromise();
     return response.json();
  }

Then in the component:

async canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
    this.loginStatus = await this.loginService.isAuthenticated();

    console.log("LOGGED IN STATUS: " + this.loginStatus);

    if (this.loginStatus == true){
        return true;
    }

    // not logged in so redirect to login page with the return url
    this.router.navigate(['/layout/login'], { queryParams: { returnUrl: state.url } });    
}

Answer 2

You can return the observable as Observable<boolean>

canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
    return this.loginService.isAuthenticated()
        .map(status => {
            console.log(status);
            this.authenticated = status;
            return true;
        }).catch((err) => {
            console.log(err);
            return Observable.of(false);
        });
}