Angular4 Routing: Force Navigation By Bypassing Route Guard

Question

When my users have dirty changes on a screen, I have a route guard to prompt them to save or discard when they try to navigate away.

However, if I am logging them out due to inactivity, I want to force navigation and bypass the route guard (by discarding their changes), in order to ensure that their screen is blanked.

How can I bypass route guards?

Answer 1

My solution was as follows:

My logout method after successfully logging out, redirects the app to the /login route:

@Injectable
export class AuthService {
  // ...
  logout () {
    // do logout
    this.router.navigate(['/login']);
  }
}

My guard is then as follows:

@Injectable
export class DiscardChangesGuard implements CanDeactivate<MyComponent> {

  canDeactivate(component: MyComponent, currentRoute: ActivatedRouteSnapshot,
                currentState: RouterStateSnapshot, nextState?: RouterStateSnapshot): Observable<boolean> | boolean {

    if (nextState.url === '/login') {
      return true; // bypass checks if we are trying to go to /login
    }

    // perform regular checks here
  }
}

Answer 2

Here's how you can force a bypass on a per-navigation basis. In my case I was navigating back to the account dashboard after the user submits a form with account info.

Ideally you would check for unsaved changes in the form and bypass based on that, but my forms don't have that feature yet.

form component:

this.router.navigateByUrl('/', { state: { bypassFormGuard: true } })

router guard:

@Injectable()
export class ExitFormGuard implements CanDeactivate<ComponentCanDeactivate> {

   constructor(private router: Router) {}

   canDeactivate(component: ComponentCanDeactivate): boolean | Observable<boolean> {
      if (this.router.getCurrentNavigation()?.extras?.state?.bypassFormGuard) {
         return true
      }

      // perform normal checks
   }
}