Conditionally load module on the empty path in Angular router

问题

I'm trying to load the home page of my app for visitors who are not authenticated.

const routes: Routes = [
    { path: '', loadChildren: './home/home.module#HomeModule' }
...

Authenticated users should get their feed via that module, also on the empty path.

{ path: '', loadChildren: './feed/feed.module#FeedModule', canActivate: [IsAuthenticationGuard] },
{ path: '', loadChildren: './home/home.module#HomeModule', canActivate: [NoAuthenticationGuard] },

I would expect that IsAuthenticationGuard would fail and load the default home component.

Instead it DOES download the feed module package (shown in the network tab) but loads nothing in the router outlet. Very confusing.

How can I do conditional routing (based on guards or otherwise) on the empty path?

Update: Here are the guards by request

@Injectable()
export class IsAuthenticationGuard implements CanActivate {
    constructor(
        private authenticationService: AuthenticationService
    ) { }

    public canActivate(
        route: ActivatedRouteSnapshot,
        state: RouterStateSnapshot
    ): Observable<boolean> {
        return this.authenticationService.isAuthenticated.pipe(take(1), map((isAuthentication) => {
            return isAuthentication;
        }));
    }
}

I've researched the new urlTree and it's cool that you can now redirect via the route instead of within the guard. However, redirects don't seem applicable if you're trying to use the same route with a different module. Plz correct me if there is a way.

回答1:

There are a couple things that you are doing wrong in my opinion.

You shouldn't have two routes defined with the same path.
In your guard the map is pointless. As long as your service method returns Observable<boolean> you don't need to map its value.
Also in your guard if you're not returning true, you need to navigate to the other module's path. For that you will need to implement some other logic for telling whether the user is logged in or not.

Take a look at the official angular routing guide here. There is a lot of useful information that will help you. Especially these:

recommended guard implementation
debugging routing in your application

EDIT 2018/12/27

So if the question is how to conditionally load two feature modules on the same path,

the answer is, in my experience, you cannot.

回答2:

It turns out that this was basically not (safely) possible until Ivy. Now in Angular 9/10 we can lazy load feature-modules without the router very easily.

StackBlitz

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
})
export class AppComponent implements OnInit  {
  @ViewChild('container', { read: ViewContainerRef }) container: ViewContainerRef;

  constructor( 
    private compiler: Compiler,
    private injector: Injector
  ){  }

  public ngOnInit(): void {
      if (loggedin) {
          this.loadModule(await import('./lazy/lazy.module').then(m => m.LazyModule));
      } else {
          this.loadModule(await import('./lazy2/lazy2.module').then(m => m.Lazy2Module));
      }
  }

  async loadModule(module: Type<any>) {
      let ref;
      try {
          this.container.clear();
          const moduleFactory = await this.compiler.compileModuleAsync(module);
          const moduleRef: any = moduleFactory.create(this.injector);
          const componentFactory = moduleRef.instance.resolveComponent(); // ASSERTION ERROR
          ref = this.container.createComponent(componentFactory, null, moduleRef.injector);
      } catch (e) {
          console.error(e);
      }
      return ref;
  }
}

回答3:

I believe what you intend to achieve is not possible through guards. Angular searches the routes array from top to bottom and as soon as it gets a path match, the corresponding module/component is loaded. In your case, { path: '', loadChildren: './feed/feed.module#FeedModule', canActivate: [IsAuthenticationGuard] } is a url path match and thus Angular loads the Feed Module, however does not display anything as the guard returns failure. It doesn't even proceed to check the url match for line below.

Instead what you can do is,

change the routes as { path: '', loadChildren:'./home/home.module#HomeModule', canActivate: [IsAuthenticationGuard] },
navigate to feed module if the user is authenticated succesfully. Follow this thread to get more clue on how to do this.

I hope this solves your purpose.

回答4:

Try maybe this:

const routes: Routes = [
  { path: '', redirectTo: condition ? 'home' : 'feed', pathMatch: 'full' },
  { path: 'home', component: HomeComponent },
  { path: 'feed', component: FeedComponent },
  { path: '*', redirectTo: 'home', pathMatch: 'full' },
];

That's not directly based on Guards, but you should probably be able to get your Guard return as the condition

来源：https://stackoverflow.com/questions/53937128/conditionally-load-module-on-the-empty-path-in-angular-router

标签

javascript

angular

module

routing