Cache exclusion

Me third! I have a module that generates a random node out of my database but if I turn cache on, the module outputs the same node each time. I need something to exclude this module from being cached by drupals cache.
I use 4.5...

VideoJunky.Net

The "don't cache" option for the php filter format isn't honored if an anonymous user is accessing the page. A "TEMPORARY" cache entry is created, wich will be removed by a cache_clear_all call.

So I added a cache_clear_all call to cron.php. That removes all expired pages on each cron run.

Not perfect, but it works for me, because my dynamic pages are only updated every two hours.

The caching is controlled by the result of variable_get('cache',0) when the user is anonymous and it's a GET request. This function in turn uses $GLOBALS['config']['cache'].

So to prevent a particular page being cached, while leaving the normal page cache on, simply set $GLOBALS['config']['cache'] to false somewhere in that page's code. The page will then not be cached at all, so no need for exit() functions to remove it from the cache later.

Thanks to Tolmács Márk for his comment in http://drupal.org/node/233979 that showed me the way.

My particular problem was for multi-page forms that were used by anon users. The entered values were stored in the session, so you could go backwards through the form pages. The problem was that the initial form page was always displayed with a GET request, so was being served from the page cache, rather than being generated with the correct default data. I now set the global variable above to false in my module's custom form_alter() function, when the form_id matches one of the affected forms.

Has there been any move to add this to the drupal core, (or perhaps to 4.7?)

It would be very useful to disable the drupal cache on a module-by-module basis.

For some modules (eg my current issue with captcha) it just doesn't seem appropriate to cache them since you would always want a "fresh" version to be generated.

Anybody?

I'm using 4.7.3 and experienced the same problem in combination with the guestbook.module. Does this 'hack' also work for this version? Where do i place the code in this version? The function page_set_cache doesn't exist in the bootstrap.inc.

Thanx in advance.

<?php $GLOBALS['do_not_cache'] = 1 ?>

How/where is this inserted into specific nodes?

The snippet below worked for me. And, I think it works better using the preg_match rather than ereg, just don't forget to trim and escape the slashes.

function cache_exclusion_exit($destination = NULL) {
global $base_root;

if ($destination == NULL) {
$pages = explode("\n", variable_get('cache_exclusion_list', ''));
$this_page = request_uri();
foreach ($pages as $page) {
$page = preg_replace("/\//", "\/",$page);
//echo $page." - ".$this_page."
";
if(preg_match("/".$page."/", $this_page)) {
db_query("DELETE FROM {cache} WHERE cid = '%s'", $base_root . request_uri());
}
}
}
}

Jason Kadarusman
Web Developer
Achieve Internet
1767 Grand Ave. Ste 2
San Diego, CA 92109

I hope you don't mind, but I've submitted that mini-module to CVS:

http://drupal.org/project/cacheexclude

If you have a CVS account, contact me and let me know if you want CVS access on it. You wrote it, I just packaged it up. :-) Cheers!

--
Larry Garfield
http://www.garfieldtech.com/blog

came across this post while trying to deal with a related issue. thought i'd post a link to my solution just in case it's helpful to anyone else who comes across this thread. thanks to those who posted here (a long time ago); these notes pointed me in the right direction.

i needed to force the page cache to clear frequently for just a few specific dynamic pages. (in my case, i wanted "upcoming events" queries to be re-run a few times per day, so that outdated events would be removed from the list. because new content was not being created frequently, the page cache was not being cleared often enough.)

i created a very simple module to delete specific pages each time cron.php is called. then i created a separate cron task that accessed those same pages, so that the page cache would be (almost) immediately re-populated with new data based on up-to-date calculations.

if this would help you, take a look at the code and more detailed explanation