Prevent Caching

slevytam

Hello,

I am having a problem with caching...

I have a page which displays thumbnails.

The user can delete or add thumbnails to specific positions. Each position has a filename associated with it.

If the user deletes thumbnail from position one it disappears correctly. If users loads a different pic into pos 1 the old one appears again. If refresh is hit then the correct pic appears.

I think ie is going to the cached pic since the filenames are the same.

How can I force ie to reload the pic. I've tried:
<?php ob_start();
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

at the top of my page; however, it doesn't make a difference. Should I put something in the link that recalls the page?

Any help would be appreciated.

Thanks,

--SL

stolzyboy

echo

If you include a variable which changes in the url then this forces the browser to look for a new page:

<A HREF="page.php?t=<? echo(time());?>">get current data<?a>

slevytam

Thanks for your reply.

I'll try the meta tag and see if it helps...

--SL

slevytam

Nope,

Still doesn't work. IE keeps displaying the cached image.

--SL

slevytam

Hello,

time() didn't work after the url. Probably because the image gets called dynamically through php.

Thanks though,

--SL

slevytam

Hello again,

I attached time() to the src of the img tag and it seems to be working

Thanks,

--SL

feldon23

If the user deletes thumbnail from position one it disappears correctly. If users loads a different pic into pos 1 the old one appears again. If refresh is hit then the correct pic appears.

It's not caching, it's that PHP scripts are not executed asynchronously.

If you upload a new image, PHP sends the results of the script to the browser and THEN when the OS gets around to it, it replaces the graphic. It does not wait until the OS is finished doing PHP-requested tasks before running the rest of the PHP task. You've gotta think multithreaded...

So what I've had to do in my case is redirect page as a go-between between the form and the results of the form. And image uploads can take 10-15 seconds to kick in on a server. 🙁

I would just put a note on the upload form "Image uploads may not immediately take effect--this is normal. To see the changes, Refresh this page after 15-30 seconds."

slevytam

Great! This gives me some background on the problem.

I did solve mine though by using this:

Thanks,

--SL