ASP.NET MVC : how do I return 304 "Not Modified" status?

Question

ASP.NET MVC 3.0, IIS 7, .NET 4

I have an action that returns data that seldom changes (almost static).

Is there an easy way to:

return 304 "Not Modified" from action;
include "Last-Modified" time stamp in the response.

I use return Content('my data'); for action result.

Basically I want an easy way to do what is talked about in this article : http://weblogs.asp.net/jeff/archive/2009/07/01/304-your-images-from-a-database.aspx

Similar Q&A for .NET core can be found [in this question](https://stackoverflow.com/questions/43351192/how-to-return-a-304-result-from-asp-net-core-web-api) — GolezTrol, Feb 12 '18 at 16:38

score 17 · Accepted Answer · answered Sep 20 '12 at 21:36

17

(Very!) late answer but this question pops up near the top in search engine results so it might be useful to future people landing here.

Alternative for part 1:

return new HttpStatusCodeResult(304, "Not Modified");

answered Sep 20 '12 at 21:36

Kntajus

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1
5

CD.. · Answer 2 · 2012-07-08T11:37:37.790

10

Whats wrong with this for 304?

        Response.StatusCode = 304;
        Response.StatusDescription = "Not Modified";
        return Content(String.Empty);

and this for LastModified:

        Response.Cache.SetLastModified(DateTime.Now);

Or maybe just create a 'Not Modified' Filter.

edited Jul 08 '12 at 11:37

answered Apr 27 '11 at 20:38

CD..

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too much typing. I am hopeful there is a built way to do that, something like : `return NotModified(myResource.LastModified);` – THX-1138 Apr 27 '11 at 20:44
3

more importantly I still need to check and parse "If-Modified-Since" in request, and that's become too complex for me. – THX-1138 Apr 27 '11 at 20:48
"'Not Modified' Filter." link is broken – Simon Jul 08 '12 at 10:02

score 1 · Answer 3 · answered Aug 26 '16 at 09:00

use the material provided, you can build a small utility function in your controller

protected bool CheckStatus304(DateTime lastModified)
{
    //http://weblogs.asp.net/jeff/304-your-images-from-a-database
    if (!String.IsNullOrEmpty(Request.Headers["If-Modified-Since"]))
    {
        CultureInfo provider = CultureInfo.InvariantCulture;
        var lastMod = DateTime.ParseExact(Request.Headers["If-Modified-Since"], "r", provider).ToLocalTime();
        if (lastMod == lastModified.AddMilliseconds(-lastModified.Millisecond))
        {
            Response.StatusCode = 304;
            Response.StatusDescription = "Not Modified";
            return true;
        }
    }

    Response.Cache.SetCacheability(HttpCacheability.Public);
    Response.Cache.SetLastModified(lastModified);

    return false;
}

then use it like this:

if (CheckStatus304(image.CreatedDate)) return Content(string.Empty);

ASP.NET MVC : how do I return 304 "Not Modified" status?

3 Answers3

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