Angular router: navigating to different routes according to the user's role

Question

I'm writing a mock e-commerce app which has the following structure:

• app
  • auth
    • sign-in-page
    • sign-up-page
    • auth-routing.module.ts

      const routes: Routes = [
        {
          path: 'signup',
          component: SignUpPage,
        },
        {
          path: 'signin',
          component: SignInPage,
        },
      ];
      

    • auth.module.ts
  • admin
    • root-page
    • admin-routing.module.ts

      const routes: Routes = [
        {
          path: 'admin',
          component: RootPage,
          children: [
            // ...                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
          ],
        },
      ];
      

    • admin.modules.ts
  • customer
    • root-page
    • catalog-page
    • check-out-page
    • thank-you-page
    • customer-routing.module.ts

      const routes: Routes = [
        {
          path: 'customer',
          component: RootPage,
          children: [
            { path: 'catalog/:categoryId', component: CatalogPage },
            { path: 'checkout', component: CheckOutPage },
            { path: 'thankyou', component: ThankYouPage },
          ],
        },
      ];
      

    • customer.module.ts
  • page-not-found
  • app-routing.module.ts

    const routes: Routes = [
      { path: '**', component: NotFoundPage },
    ];
    

  • app.module.ts
  • app.component.html
  • app.component.css

The basic workflow is supposed to be as follows:

0. The user navigates to the root path /.
1. The application detects that they are not logged in, so it redirects them to /signin.
2. They enter their credentials and press Sign In.
3. If the authentication is successful,
   1. If the user is an admin, they get redirected to /admin.
      1. admin-router.module.ts redirects them to some sub-path of /admin.
   2. If the user is a customer, they get redirected to /customer.
      1. customer-router.module.ts redirects them to /customer/catalog/<default category ID>.
      2. They put some products in the shopping cart and proceed to /customer/checkout.
      3. They place the order and get redirected to /customer/thankyou.

What I'm not sure about is how to accomplish the redirection following a successful log-in. Obviously it has to be done in two stages: first to some common path such as / and then either to /customer or to /admin depending on the user's role. The second stage probably needs to be handled by app-routing.module.ts, perhaps using a guard, but I'm not sure exactly how to do it.

EDIT (2021-04-20)

The problem can be summarized as follows:

What I need is a way (preferably declarative) to redirect the application from / to one of the following paths depending on its state:

State	Path
Logged out	/auth
Logged in as a customer	/customer
Logged in as an admin	/admin

Answer 1

What I ended up doing is this:

// app-routing.module.ts

const routes: Routes = [
  {
    path: '',
    canActivate: [AuthorizationGuard],
    children: [],
  },
  { path: '**', component: NotFoundPage },
];

// authorization.guard.ts

@Injectable({
  providedIn: 'root',
})
export class AuthorizationGuard implements CanActivate {

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

  canActivate(
    route: ActivatedRouteSnapshot,
    state: RouterStateSnapshot
  ): UrlTree {
    const user = this.authService.getLoggedInUser();
    return (
      (user?.role === 'admin' && this.router.parseUrl('/admin')) ||
      (user?.role === 'customer' && this.router.parseUrl('/customer')) ||
      this.router.parseUrl('/auth')
    );
  }

}

Answer 2

You could create some dummy component and protect it with a guard that handles the correct navigation. Something like this:

[
  {
    path: 'loggedin',
    component: DummyComponent,
    canActivate: [HandleLoginGuard]
  },
  {
    path: 'admin',
    component: AdminComponent,
  },
  {
    path: 'customer',
    component: CustomerComponent,
  }
]


@Injectable()
class HandleLoginGuard implements CanActivate {
  canActivate(
    route: ActivatedRouteSnapshot,
    state: RouterStateSnapshot
  ) {
    if(isAdmin()){
        route.navigate(/admin);
    }else{
        route.navigate(/customer);
    }
    return false;
  }
}

This way you can put the logic in a guard instead of the login component.