Angular 16 - solution with Implementing Route Guards for Nested Routes with Async Data Fetching
I've looked through the documentation and I'm still confused about I've been trying to implement route guards for my nested routes in an Angular 16 application, but I'm running into issues with guards that depend on asynchronous data fetching. My guard should check whether the user has the necessary permissions before allowing access to a specific route, but the asynchronous call to fetch the user's permissions seems to be causing some unexpected behaviors. Here’s a simplified version of my route configuration: ```typescript const routes: Routes = [ { path: 'home', component: HomeComponent }, { path: 'admin', component: AdminComponent, canActivate: [AuthGuard], children: [ { path: 'settings', component: SettingsComponent }, { path: 'users', component: UsersComponent } ] } ]; ``` And here's a snippet of my `AuthGuard` implementation: ```typescript @Injectable({ providedIn: 'root' }) export class AuthGuard implements CanActivate { constructor(private authService: AuthService, private router: Router) {} canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<boolean> | Promise<boolean> | boolean { return this.authService.getUserPermissions().pipe( map(permissions => { const hasAccess = permissions.includes('ADMIN'); if (!hasAccess) { this.router.navigate(['/home']); } return hasAccess; }), catchError(() => { this.router.navigate(['/home']); return of(false); }) ); } } ``` The question occurs when I navigate to `/admin/settings`. If the permissions are still being fetched when the route guard runs, it can lead to unexpected behavior where the guard resolves before the HTTP call completes. I sometimes see that the route is allowed even when the user shouldn't have access. The console also shows `behavior behavior: Uncaught (in promise): TypeError: want to read properties of undefined (reading 'includes')` intermittently, which seems to indicate that the permissions array isn't defined yet. I've tried wrapping my `getUserPermissions()` in a `BehaviorSubject` to ensure that the most recent value is emitted, but that hasn't helped resolve the timing scenario. Can someone suggest a better way to handle async checks in route guards or perhaps a workaround for this situation? Any insights would be greatly appreciated! I'm working on a CLI tool that needs to handle this.