Angular2 + ngrx/store for handling failure HTTP requests

Question

I want to have a simple code path for creating and dispatching HTTP actions. What I would like to do is something like:

this.http.request(...)
  .map((res: Response) => res.json())
  .catch((err: any) => err.json())
  .map((payload: any) => { type: 'SUCCESS', payload })
  .catch((payload: any) => { type: 'FAILURE', payload})
  .subscribe((action: Action) => this.store.dispatch(action));

That way both the success and failure responses are converted to JSON and then based upon the success/fail criteria assign the correct reduction type so that the store can be operated on properly. (think user login success and failure which returns a 200 or 401).

Is there a cleaner or better way of handling this? Current the 2nd .catch doesn't play well since it is not returning an observable.

Suggestions or other solutions welcome?

Answer 1

From the example-app from ngrx, for this case is recommended to use @Effects(check the docs folder), and IMO, is a more clear way, check the service:

@Injectable()
export class AuthService {
    private headers: Headers;
    private API_ENDPOINT: string = "/api/user/";

    public constructor(
        private http: Http,
        private localStorageService: LocalStorageService
        ) {
        this.headers = new Headers({ 'Accept': 'application/json' });
    }

    public login(email: string, password: string): Observable<AuthUser> {
        return this.http
        .post(this.API_ENDPOINT + 'login', { 'email': email, 'password': password }, this.headers)
        .map(res => res.json().data as AuthUser)
        .catch(this.handleError);
    }

    private handleError(error: Response | any) {
        let body = error.json();
        // .. may be other body transformations here
        console.error(body);
        return Observable.throw(body);
    }
}

And check the Effect:

@Injectable()
export class AuthEffects {

    constructor(
        private actions$: Actions,
        private authService: AuthService,
        private localStorageService: LocalStorageService
    ) { }

    @Effect() logIn$: Observable<Action> = this.actions$
        .ofType(auth.ActionTypes.LOGIN)
        .map((action: Action) => action.payload as LoginCredentials)
        .switchMap((credentials: LoginCredentials) => this.authService.login(credentials.email, credentials.password))
        .do((user: AuthUser) => this.localStorageService.setUser(user))
        .map((user: AuthUser) => new auth.LoginSuccessAction(user))
        .catch((error) => of(new auth.FlashErrors(error)));

}

Off course, you need to setup the Effects on appModule:

@NgModule({
imports: [
    StoreModule.provideStore(reducer),
    EffectsModule.run(AuthEffects),
    RouterStoreModule.connectRouter(), // optional but recommended :D
],
declarations: [...],
providers: [AuthService, LocalStorageService, ...]
})
export class AuthModule {}

Read more about ngrx/effects on the docs folder from the repo.

Answer 2

In one of my services I do it like this:

get(url, actionType) {
  this._http.get(BASE_URL + url)
    .map(response => response.json())
    .map(payload => ({ type: actionType, payload }))
    .subscribe(action => this.store.dispatch(action), error => this._apiErrorHandler(error));
}

private _apiErrorHandler(response) {
  let payload = response.json().error;
  this.store.dispatch({ type: 'API_ERROR', payload });
}