For three days I had nearly despaired when I tried to extend a WordPress site with a self-written login script. Everything worked properly on my local server, but as soon as I had uploaded it, the session variables didn’t seem to be passed any more: after the login, I stayed logged in for only one more click and then got logged out again.
After several unsuccessful Google searches (with the wisdom of hindsight it’s quite easy to google, but try and find something about this issue without reading any further than this) I found the reason at last, namely the function wp_unregister_GLOBALS()
inside the file wp-settings.php
. Here it is:
function wp_unregister_GLOBALS() {
if ( !ini_get('register_globals') )
return;
if ( isset($_REQUEST['GLOBALS']) )
die('GLOBALS overwrite attempt detected');
// Variables that shouldn't be unset
$noUnset = array('GLOBALS', '_GET', '_POST', '_COOKIE', '_REQUEST', '_SERVER', '_ENV', '_FILES', 'table_prefix');
$input = array_merge($_GET, $_POST, $_COOKIE, $_SERVER, $_ENV, $_FILES, isset($_SESSION) && is_array($_SESSION) ? $_SESSION : array());
foreach ( $input as $k => $v )
if ( !in_array($k, $noUnset) && isset($GLOBALS[$k]) ) {
$GLOBALS[$k] = NULL;
unset($GLOBALS[$k]);
}
}
What does this function do?
- Line 27/28:
Ifregister_globals
is not activated in the PHP settings of the web server, it won’t do anything at all (which explains the different behaviours of my script on my local and the live server). If, however,register_globals
is active, it proceeds as follows:- Line 34:
As the comment already says, all global variables listed here will not be reset. As you can see,$_SESSION
is not being mentioned! - Line 36-41:
Now, all global variables are being shifted and deleted one by one.
- Line 34:
In short: If register_globals
is activated, $_SESSION
will be deleted on every single page view. No surprise that we can’t get at our session variables any more!
What’s it all about?
Well, for one thing, WordPress assumes that it’s meant to take care of the complete site – after all it is some kind of content management system. And that includes the administration of all variables as well.
What’s much more important though, is the fact, that the use of register_globals
has been deprecated for a long time and the feature will even be completely removed in PHP 6. Today, it is strongly recommended not to use these kind of variables, because they involve safety hazards. So, WordPress is obviously trying to imitate the behaviour of a deactivated register_globals
in order to ensure safety and avoid potential variable conflicts.
Remedy
After having solved this riddle, the solution was perfectly obvious: I have to deactivate register_globals
on the web server, so WordPress wouldn’t even need to execute that stupid function. For this purpose, simply place a text file called php.ini
inside your WordPress directory, containing the following line:
register_globals Off
Further information on the subject can be found on php.net:
73 responses to “Session variables in WordPress”
Nice… was racking my brain for the same damn thing. I’d found the wp_unregister_GLOBALS function and was 1 step behind the resolution before I decided to google what others have done to tweak this function.
I updated my php.ini and whammo.. working like a charm.. thanks for your post.
I think we must find a solution without register globals.
Thanks.
Well, if you really want to make it work with
register_globals
on (which you shouldn’t, because it’s unsafe and allows for code injections!), you could simply edit line 34 and add$_SESSION
to it, so it looks like this:After that, session variables should not be unset anymore.
Hi Ginchen,
Is it normal to use cookies? or is there a way to store global variables?
I am working on a register script which sets special roles. I am trying to build this without modify the wordpress files. I need to store clicked button’s value. Like – freelancer, firm,… After this I can use filters for setting the specified role.
If you allow users to register anyway, you could also save this information in a database, so it will be available forever. You can do database queries by using the wordpress database ID saved in
$wpdb
.If you only need the data during the registration process, Cookies would be okay, too. Or you could even pass the information to the next page using $_GET.
Hallo Ginchen,
Danke für die Info. ;)
Du hast mir das Leben gerettet. :D
Grüsse aus Antalya
Caner
Thank you so much for sharing this!! This solved a number of problems that I was experiencing. I can now get a proper nights rest.
Im was debuging for hours before find this, thanks a lot, you rock!
or you add _SESSION in the noUnset array of that function….
Well, that’s what I just suggested to Satranc in the third comment… ;)
But it is not a good solution. Hacking the WordPress core files is never a good solution.