angular - Using Resolve In Angular2 Routes

Question

In Angular 1 my config looks like this:

$routeProvider
  .when("/news", {
    templateUrl: "newsView.html",
    controller: "newsController",
    resolve: {
        message: function(messageService){
            return messageService.getMessage();
    }
  }
})

How to use resolve in Angular2?

Answer 1

Based on @angular/router v3-beta, these are the required steps.

Implement a resolver that returns an Observable or a plain value:

@Injectable()
export class HeroResolver implements Resolve {

    constructor(
        private service: HeroService
    ) {}

    resolve(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<Hero> {
        const id = +route.params['id'];
        return Observable.fromPromise(this.service.getHero(id));
    }

}

Note that in case you return an observable, the unwrapped value (first one) will be available through route.snapshot.data. If you want the observable itself to be available, then you need to wrap it in another Observable:

return Observable.of(source$);

Add the resolver to your route:

export const HeroesRoutes: RouterConfig = [
    { path: 'heroes',  component: HeroListComponent, resolve: { heroes: HeroesResolver } },
    { path: 'hero/:id', component: HeroDetailComponent, resolve: { hero: HeroResolver } }
];

Finally, provide your resolve class and any dependency to bootstrap or your main component providers:

bootstrap(AppComponent, [
    HeroesResolver, HeroService
])

Consume the resolved data from an ActivatedRoute instance:

ngOnInit() {
    this.hero = this.route.snapshot.data['hero'];
}

Remember that snapshot means the value at the state of execution, both in the component class and the resolver class. Data can't be refreshed from params updates with this approach.

Plunker: http://plnkr.co/edit/jpntLjrNOgs6eSFp1j1P?p=preview Source material: https://github.com/angular/angular/commit/f2f1ec0#diff-a19f4d51bb98289ab777640d9e8e5006R436