What is the correct response to an HTTP POST reque

问题:

For a POST method, the W3 specs say:

If a resource has been created on the origin server, the response SHOULD be 201 (Created) and contain an entity which describes the status of the request and refers to the new resource, and a Location header (see Section 10.4).

http://www.ietf.org/internet-drafts/draft-ietf-httpbis-p2-semantics-05.txt (section 8.5)

The standard response actually seems to be to send a Redirect to the newly created resource.

I'm building my site with ASP.NET MVC, and tried to follow the spec, so created a ResourceCreatedResult class:

public class ResourceCreatedResult : ActionResult
{
    public string Location { get; set; }
    public override void ExecuteResult(ControllerContext context)
    {
        context.HttpContext.Response.Clear();
        context.HttpContext.Response.StatusCode = 201;
        context.HttpContext.Response.ClearHeaders();
        context.HttpContext.Response.AddHeader("Location", Location);
    }
}

And my action looks something like this:

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult CreateNew(string entityStuff)
{
    Entity newEntity = new Entity(entityStuff);
    IEntityRepository entityRepository = ObjectFactory.GetInstance<IEntityRepository>();
    entityRepository.Add(newEntity);

    ActionResult result = new ResourceCreatedResult()
        { Location = Url.Action("Show", new { id = newEntity.Id }) };
    return result;
}

However, IE, Firefox and Chrome all fail to redirect to the new resource. Have I messed up generating the correct response, or do web browsers not expect this type of response, instead relying on servers to send a Redirect response?

回答1:

Redirect after post or post/redirect/get is something your application must do to be user friendly.

Edit. This is above and beyond the HTTP specifications. If we simply return a 201 after a POST, the browser back button behaves badly.

Note that Web Services requests (which do NOT respond to a browser) follow the standard completely and do NOT redirect after post.

It works like this.

1. The browser POSTS the data.

2. Your application validates the data. If it's invalid, you respond with the form so they can fix it and POST.

3. Your application responds with a redirect.

4. The browser gets the redirect and does a GET.

5. Your application sees the GET and responds.

Now -- hey presto! -- the back button works.

回答2:

To be explicit, browsers (including modern browsers like Firefox 3 and IE8) do not "take the hint" and follow up an HTTP 201: Created response with a GET request to the URI supplied in the Location header.

If you want browsers to go to the URI supplied in the Location header, you should send an HTTP 303: See Other status instead.

回答3:

My solution is to respond with a '201 Created' containing a simple page with a link to the new resource, and a javascript redirect using location.replace().

This lets the same code work for API and browser requests, plays nicely with Back and Refresh buttons, and degrades gracefully in old browsers.

回答4:

As stated in the spec the response SHOULD be a HTTP 201 with redirect. So it isn't mandatory for a browser vendor to implement the correct answer...

You should try to change to a 30x code to see if it is correctly redirected. If so, it's a browser problem, else it may come from your code (I don't know anything in ASP.NET so I can't "validate" your code)

回答5:

Shouldn't that only count for when something is "Created" and therefore a simple redirect to action should be genuinely sufficient?