Redirect to a different component inside @CanActivate in Angular2

Question

我们有什么方法可以从Angular2中的@CanActivate重定向到另一个组件吗？

Answer 1

As of today, with latest @angular/router 3.0.0-rc.1, here are a couple of references on how to do that through CanActivate guards on routes:

1. angular 2 reference
2. Two answers to this SO question, by Nilz11 and by Jason

The main gist of logic looks like:

// ...
canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
  if (this.authService.isLoggedIn) {
    // all ok, proceed navigation to routed component
    return true;
  }
  else {
    // start a new navigation to redirect to login page
    this.router.navigate(['/login']);
    // abort current navigation
    return false;
  }
}

Answer 2

Your guard can easily just be an injectable which, as such, can include its own injectables. So we can simply inject the router, in order to redirect . Don't forget to add the service as a provider in your app module.

@Injectable()
export class AuthGuard implements CanActivate {

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

  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<boolean> | boolean {
    if (!authService.isAuthenticated()) {
      this.router.navigate(['/login']);
      return false;
    }
    return true;
  }
}

export const ROUTES: Routes = [
  {path: 'login', component: LoginComponent},
  {path: 'protected', loadChildren: 'DashboardComponent', canActivate: [AuthGuard]}
];

Answer 3

Yes, you can! Doing this will prevent your component from instantiating for nothing.

First, make a new file src/app-injector.ts

let appInjectorRef;

export const appInjector:any = (injector = false) => {
    if (!injector) {
        return appInjectorRef;
    }

    appInjectorRef = injector;

    return appInjectorRef;
};

Then, get the reference from bootstrap

// ...
import {appInjector} from './app-injector';
// ...


bootstrap(App, [
  ROUTER_PROVIDERS
]).then((appRef) => appInjector(appRef.injector));

Finally in your function

// ...
import {appInjector} from './app-injector';
// ...

@CanActivate((next, prev) => {
  let injector = appInjector();
  let router = injector.get(Router);

  if (42 != 4 + 2) {
    router.navigate(['You', 'Shall', 'Not', 'Pass']);
    return false;
  }

  return true;
})

Et voilà !

It was discussed here https://github.com/angular/angular/issues/4112

You can find a complete example here http://plnkr.co/edit/siMNH53PCuvUBRLk6suc?p=preview by @brandonroberts

Answer 4

This might help someone who is trying to wait on something before continuing.

waitForBonusToLoad(): Observable<[boolean, string]> {

const userClassBonusLoaded$ = this.store.select(fromRoot.getUserClasssBonusLoaded);
const userClassSelected$ = this.store.select(fromRoot.getClassAttendancesSelectedId);

return userClassBonusLoaded$.withLatestFrom(userClassSelected$)
  .do(([val, val2]) => {
    if (val === null && val2 !== null) {
      this.store.dispatch(new userClassBonus.LoadAction(val2));
    }
  })
  .filter(([val, val2]) => {
    if(val === null && val2 === null) return true;
    else return val;
  })
  .map(val => {
    return val;
  })
  .take(1);
}

canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<boolean> {
return this.waitForBonusToLoad().map(([val, val2]) =>
  {
    if(val === null && val2 === null){
      this.router.navigate(['/portal/user-bio']);
      return false;
    }
    else {
      return true;
    }
  }
)
}

Answer 5

If you are using an observable to determine, you can leverage tap operator from rxjs :

@Injectable({
  providedIn: SharedModule // or whatever is the equivalent in your app
})
export class AuthGuard implements CanActivate {

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

  canActivate(next: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<boolean> {
    return this.authService.isLoggedIn()
      .pipe(tap((isLoggedIn: boolean) => {
        if (!isLoggedIn) {
          this.router.navigate(['/']);
        }
      }));
  }

}

Answer 6

As of Angular 7.1, you can return UrlTree instead of boolean :

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

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

  canActivate(): boolean | UrlTree {
    return this.authService.isAuthenticated() || this.router.createUrlTree(['/login']);
  }
}