+ const url = `${this.heroesUrl}/${id}`;
+ return this.http.get<Hero>(url).pipe(
+ tap(_ => this.log(`fetched hero id=${id}`)),
+ catchError(this.handleError<Hero>(`getHero id=${id}`))
+ );
+ }
+
+ /**
+ * 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.
+ if (result === undefined) {
+ return EMPTY as Observable<T>;
+ } else {
+ return of(result as T);
+ }
+ };