+ this.log(`requested hero id=${id}`);
+ const found: Hero | undefined = HEROES.find(hero => hero.id === id);
+ if (found === undefined) {
+ return EMPTY;
+ } else {
+ return of(found);
+ }
+ }
+
+ /**
+ * Handle Http operation that failed.
+ * Let the app continue.
+ * @param operation - name of the operation that failed
+ * @param result - optional value to return as the observable result
+ */
+ private handleError<T>(operation = 'operation', result?: T) {
+ return (error: any): Observable<T> => {
+
+ // TODO: send the error to remote logging infrastructure
+ console.error(error); // log to console instead
+
+ // TODO: better job of transforming error for user consumption
+ this.log(`${operation} failed: ${error.message}`);
+
+ // Let the app keep running by returning an empty result.
+ return of(result as T);
+ };
+ }
+
+ /** Log a HeroService message with the MessageService */
+ private log(message: string) {
+ this.messageService.add(`HeroService: ${message}`);