Setting ASP.NET Cache control headers

Question

In my asp.net forms app. I'm trying to prevent caching of certain pages. to do so I've set a series of cache control headers using Response.AppendHeader e.g.

protected override void OnLoad(Eventargs e) 
{
...
Response.ClearHeaders();
Response.AppendHeader("Cache-Control","no-cache");
....
base.OnLoad(e);
}

Trouble is when I view my site and look at the Net tab in the Firefox console to view the request/response headers I see a behavior as follows:

a POST request/response for the page1.aspx which triggers a redirect (to page2.aspx) the response here contains the correct headers.
a GET request/response for page2.aspx associated response has the cache-control header just has a value 'pre-check=0'

That second request seems to allow the caching to happen for the page.. note: page1.aspx and page2.aspx both have the OnLoad logic I describe above. Also if I take some action on page2.aspx, the POST response will again have the correct headers.

What am I missing here? My expectation was that with the logic in OnLoad should mean that I always get the headers in the response and therefore 'always' get the current version of the page?

What I'm seeing is firefox loading it's cached version of the page.

I'm considering creating a random identifier in the request url to force the matter, but that seems a little heavy handed.

-----update----- It seems that, this may be related to having the caching code in 'OnLoad'. I've added these headers to the Page_Load() of the page and it works fine? any thoughts.

David Brainer · Accepted Answer · 2012-01-12 19:17:11Z

8

Try swapping out Response.AppendHeader("Cache-Control","no-cache"); for

Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetNoStore();

and make sure that you do not have an @ OutputCache directive and are not explicitly preventing cache control. See this MSDN page on SetCacheability and SetNoStore.

edited Jan 12, 2012 at 19:17

answered Jan 9, 2012 at 16:41

David Brainer

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2 Comments

TygerKrash Over a year ago

see my additional notes above.

David Brainer Over a year ago

@TygerKrash Could your headers be overwritten at some point? What happens in base.OnLoad? Can you step through the code and a) verify that the code which sets cache control is hit and b) watch the response object to see where it is changing?

JustinStolle · Accepted Answer · 2013-09-08 19:00:21Z

1

You might try this page-directive instead:

<%@ OutputCache Location="None" VaryByParam="None" %>

See also: How to: Set the Cacheability of an ASP.NET Page Declaratively

answered Sep 8, 2013 at 19:00

JustinStolle

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1 Comment

mehrdad seyrafi Over a year ago

This line of code is related to Server-Side caching. The question is only related to client-side caching which is completely different case.

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