$HTTP_IF_MODIFIED_SINCE

[Anon]

Hi all

I can't work out why no value is being passed from the client for If-Modified-Since...

This is the code:

session_cache_limiter("private");

$intWeek = time() + 604800;

$expires_mod = gmdate('D, d M Y H:i:s', $intWeek) . ' GMT';

header ("Expires: $expires_mod");
header ("Cache-Control: public");

( ...random db stuff here... )
( ... $rowHist now contains the date of the last update to relevant tables ... )

$dtLastChange = strtotime($rowHist["last_change"]);
$dtLastView = strtotime($HTTP_IF_MODIFIED_SINCE);

//If the numbers haven't been updated since the last view, send a 304 header
if ($dtLastChange == $dtLastView) {

    Header("HTTP/1.1 304 Not Modified");
    print("<br>304 here!");

// exit;

} else {

    Header("Last-Modified: $gmdate_mod");

    print("<br>Last Modified here!.... $gmdate_mod");

}

The problem is that no value ever arrives for $HTTP_IF_MODIFIED_SINCE... What could be the problem?

Thanks,

Andy

[Anon]

There's no guarantee that that variable is going to be set - it depends on how the browser handles cache.

So your code should be able to handle the case where no date is sent from the browser.

Diego

[Anon]

Thanks for that.

So if no date is received, I guess the code should just go ahead and reload the page... Unless there's any other way to force the page into the cache?