Update URL with new parameter value in controller action

I have an action that takes an id as a parameter and gets the corresponding item with the help of a web service. The web service's method that returns the item will either return the item with the requested id, or will create a new item (new version of the item) with a new id. So, in the case that a new item is created, the response's header should be updated with the new item's id.

Here's what the route corresponding to that controller action looks like:

public override void RegisterArea(AreaRegistrationContext context)
{
    context.MapRoute(
        "default",
        "MyArea/{Controller}/{action}/{id}",
        new { controller = "MyController", action = "Index", id = UrlParameter.Optional }
    );
}

So when an user requests the item with the id 12, the request's path will look like:


MyArea/MyController/MyAction/12

Let's say the web service creates a new version of the above item, and its id is 13, I'd like to update the URL accordingly. Here's what my action looks like:

[HttpGet]
public async Task EditItem(int id)
{
    try
    {
        Item myItem = await _myWS.Channel.GetItemAsync(id);

        // If a new version has been created, change the url in order to show the new id
        if (myItem.Id != id)
        {
            Response.StatusCode = 301;
            string newUrl = Request.Path;
            int lastSlashIndex = newUrl.LastIndexOf("/");
            if (lastSlashIndex > 0)
                newUrl = newUrl.Substring(0, lastSlashIndex + 1) + myItem.Id;

            Response.AddHeader("Location", newUrl);
            Response.End();
        }

        return View("MyView", (ItemViewModel)myItem);
    }
    catch (Exception ex)
    {
        throw new ApplicationException(ex.Message);
    }
}

I was wondering if there was a better way to reconstruct the URL with the updated id. I also tried reconstructing the URL with the Request.RequestContext.RouteData.Values, but I thought the code was less readable and more complicate

I believe you want RedirectToActionPermanent:

if (myItem.Id != id)
{
    return RedirectToActionPermanent("EditItem", new { id = id })
}

StackExchange Code Review Q#158307, answer score: 4