SQL error on site logout

Hi,

I have installed Community builder to interact with another plugin (Joomdle) that exports user Data onto another website upon registration in Joomla.

I have added the CB login module onto my site homepage, and removed the default Joomla login form module.

I am experiencing an issue when logging out of the site. When any user logs out more than once in the same session taken to the following page:

/index.php/cb-logout/logout

An SQL database error is then displayed on the page as below, the rest of the page is blank:

Duplicate entry '' for key 'PRIMARY' SQL=INSERT INTO `jos_session` (`session_id`, `client_id`, `guest`, `time`, `userid`, `username`) VALUES ('', 0, 1, '0', 0, '')

The issue resolves itself once I disable the CB plugin and re-enable the default login form.

I have done some investigation into this and can see that the 'Jos_session' table in the Joomla database appears to not be cleared down properly after the first logout, Leaving a row with a blank session ID. I have attached the contents of Jos_session after login for the first time and after the second time for comparison.


I am running

Joomla 3.3.6 stable
CB 2.0.4
PHP 5.4.34
MYSQL 5.1

If you need anything else to help troubleshoot let me know.

Can you advise on how I can resolve this issue? Thanks.

Empty your _session table then see if issue comes up again. I've no idea why something is trying to manually insert a session row. CB doesn't do any inserts directly to _session. We use Joomla session API directly. On logout CB clears the session and resets is the same way Joomla does, which re-establishes a guest session on logout. No session should have an empty key. My guess is whatever you're using to interact between CB and Joomdle is likely causing this; especially if it's trying to do some behavior on login/logout.

Hi,

Sorry I should have mentioned this in the original reply but i've already cleared the jos_session table by truncating the table, this stops the error occuring on the next logout, but the issue then re-appears.

I have the query log for login/logout, I can see the offending SQL:

FROM `jos_session`
WHERE `session_id` = '' LIMIT 0, 1
74 Query INSERT INTO `jos_session`
(`session_id`, `client_id`, `time`) VALUES
('', 0, '1417444365')
74 Query UPDATE `jos_session`
SET `data` = '__default|a:2:{s:22:\"session.client.browser\";s:108:\"Mozilla/5 .0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0. 2171.95 Safari/537.36\";s:15:\"session.counter\";i:1;}'
, `time` = '1417444365'


If this is not CB inserting this data then I'm not sure what is, as this issue disappears when I remove CB login, can you suggest how I might troubleshoot this further? Thanks

The full query log for the logout operation is attached.

Your invalid insert is directly after the jmoodle extension has loaded. See the below.


jmoodle is loading, then querying for a session with no session id, then inserting one. My guess it's a part of jmoodle behavior. Disable jmoodle extension, empty your session table, then retest to see if the issue persists.

Hi Kyle, Thanks for finding that. Disabling Joomdle does indeed fix this issue. I will raise it with the Joomdle devs to see if they can do anything to fix this.