ASP.NET MVC : how do I return 304 “Not Modified” s

问题:

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:

1. return 304 "Not Modified" from action;
2. 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

回答1:

(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");

回答2:

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.

回答3:

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);