How to get MVC action to return 404

问题:

I have an action that takes in a string that is used to retrieve some data. If this string results in no data being returned (maybe because it has been deleted), I want to return a 404 and display an error page.

I currently just use return a special view that display a friendly error message specific to this action saying that the item was not found. This works fine, but would ideally like to return a 404 status code so search engines know that this content no longer exists and can remove it from the search results.

What is the best way to go about this?

Is it as simple as setting Response.StatusCode = 404?

回答1:

There are multiple ways to do it,

1. You are right in common aspx code it can be assigned in your specified way
2. throw new HttpException(404, "Some description");

回答2:

In ASP.NET MVC 3 and above you can return a HttpNotFoundResult from the controller.

return new HttpNotFoundResult("optional description");

回答3:

In MVC 4 and above you can use the built-in HttpNotFound helper methods:

if (notWhatIExpected)
{
    return HttpNotFound();
}

or

if (notWhatIExpected)
{
    return HttpNotFound("I did not find message goes here");
}

回答4:

Code :

if (id == null)
{
  throw new HttpException(404, "Your error message");//RedirectTo NoFoundPage
}

Web.config

<customErrors mode="On">
  <error statusCode="404" redirect="/Home/NotFound" />
</customErrors>

回答5:

I've used this:

Response.StatusCode = 404;
return null;

回答6:

In NerdDinner eg. Try it

public ActionResult Details(int? id) {
    if (id == null) {
        return new FileNotFoundResult { Message = "No Dinner found due to invalid dinner id" };
    }
    ...
}

回答7:

If you are working with .NET Core, you can return NotFound()

回答8:

None of the above examples worked for me until I added the middle line below:

public ActionResult FourOhFour()
{
    Response.StatusCode = 404;
    Response.TrySkipIisCustomErrors = true; // this line made it work
    return View();
}

回答9:

I use:

Response.Status = "404 NotFound";

This works for me :-)

回答10:

In .NET Core 1.1:

return new NotFoundObjectResult(null);

回答11:

You can also do:

        if (response.Data.IsPresent == false)
        {
            return StatusCode(HttpStatusCode.NoContent);
        }

回答12:

Please try the following demo code:

public ActionResult Test()

{
　　return new HttpStatusCodeResult (404,"Not found");
}