Caching

NeoGeo

I have this application and one of the pages for it cannot have cacheing. This is because one of the options is to change an image, however when you upload a new image it overwrite the old image but keeps the same filepath and name. My problem would be easily solved by what the PHP manual says about this:

PHP scripts often generate dynamic HTML that must not be cached by the client browser or any proxy caches between the server and the client browser. Many proxies and clients can be forced to disable caching with

1
2 header ("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // Date in the past
3 header ("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
4 // always modified
5 header ("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
6 header ("Pragma: no-cache"); // HTTP/1.0
7

However I have IE 6.0 and I can't get it to work, it always caches the old image until I refresh my browser.

Does anyone know a way to fix this problems?

Thanks in advance,
Ben

cmburns69

Let me make sure I understand this problem. The image is not being generated by PHP, but the page that points to the image is, right?

Example:

<html>
<? /* Do some stuff */ ?>
<img src="image.gif">
</html>

Or is the image itself being served by PHP

Example (Page with HTML):

<html>
<? /* Do some stuff */ ?>
<img src="image.php">
</html>

Image page (image.php):

<?
header("Content-type: image/gif");
$f = fopen("image.gif");
fpassthrough($f);
fclose($f);
?>

A separate HTTP request is made for both the image and the HTML page, and my guess is that the image is static on the server. Any "expires" headers that you pass from the PHP will only have to do with the PHP, and not the image.

A solution would be to add a parameter to the image name that will be ignored by the server, but will prevent the browser from caching the request:

Example:

<html>
<? /* Do stuff here */ ?>
<img src="image.gif?cacheBust=<?echo time()?>">
</html>

<b>Tom Brown</b>
Where gamers play
www.netnexus.com

NeoGeo

Well I tried two things:

One from a post I searched for:

And the one you mentioned below:

Neither seem to work with IE 6.... Do I need to include something? If it helps, here is my exact coding:

$ah_pic1 = "../ah_imgs/pic-$ID.jpg?cacheBust=time()";

if(!file_exists($ah_pic1)) {

$ah_pic1 = "../ah_imgs/not_available.jpg";

}

later I do:

echo "<img src='$ah_pic1'>";

Like I said it is still caching the same image.

Thanks for the help it is greatly appreciated!

Ben

NeoGeo

Sorry, I was changing the wrong code. Once I did things correctly it worked perfectly - thanks!

Ben