Angular HttpClient POST请求为何返回Observable<Hero>而非成功码？

Great question! Let's break down why this pattern is used in Angular's HttpClient examples:

• REST API conventions: Most modern REST APIs follow the practice of returning the full created resource when you send a POST request to create a new item. When you add a hero, the server will typically save the hero to its database, generate any missing fields (like a unique id), and send back the complete, persisted Hero object. This lets your frontend immediately have the final version of the hero—including any server-generated data you might need for subsequent actions (like editing or displaying the hero's details).

• Practical UI synchronization: If you're adding the new hero to a list in your app's UI, having the returned Hero means you can directly append it to your local array without needing to make an extra GET request to fetch the entire updated list. This keeps your UI in sync with the server efficiently and avoids unnecessary network traffic.

• You can still get just the status code if needed: The example uses the common pattern, but Angular gives you flexibility to adjust the request if you only care about the status. You can modify the request options to get the full HTTP response (including status code) or ignore the body entirely. Here's how:

  // Get full HttpResponse object (includes status, headers, body)
  addHero(hero: Hero): Observable<HttpResponse<Hero>> {
    return this.http.post<Hero>(this.heroesUrl, hero, { observe: 'response' })
      .pipe(
        catchError(this.handleError('addHero', hero))
      );
  }
  
  // Get only the status code (response body ignored)
  addHero(hero: Hero): Observable<number> {
    return this.http.post(this.heroesUrl, hero, { observe: 'response', responseType: 'text' })
      .pipe(
        map(response => response.status),
        catchError(this.handleError('addHero', hero))
      );
  }
  

• Type safety and developer experience: By specifying <Hero> as the generic type for post(), Angular automatically parses the response body into a typed Hero object. This gives you code autocompletion in your IDE and catches type-related bugs early in development, making your code more maintainable and robust.

内容的提问来源于stack exchange，提问作者user8972341