As MediaWiki 1.19 is getting ready, I'd like to offer information on how MediaWiki
1.18.0 was the most difficult MW upgrade I've ever been through.
Some background: my team administers an internal wiki at a major company with ~2000 users,
over 100 extensions (many of them custom/unreleased), and 100K articles. I've been
upgrading MW regularly since 1.11 - every release and patch - and have never had this much
trouble before, mainly because of extensions that broke in 1.18. The typical MW upgrade
takes me a day or two including regression-testing our extensions. But 1.18 has taken me
weeks and I'm still not done.
This message is meant to be constructive & helpful, not blameful: it's quite
possible that every issue was "our fault" for not keeping up on exactly which
functions & globals were being deprecated, etc. I'd just like to describe what
kinds of things broke for a reasonably active wiki run by well-meaning people, and to
document how we fixed them.
So, here's the list of what we had trouble with, and what we did. I welcome any
improvements to our fixes!
1. The global variable $action disappeared, breaking a bunch of our extensions. I
switched to $wgRequest->getVal('action').
2. The removal of Xml::hidden() caused one of our extensions to break. I switched to
Xml::input(..., array('type', 'hidden'))
3. A few of our older extensions were not ported to ResourceLoader yet and were
adding JS and CSS via $wgOut->add... calls. They worked in 1.17 and all broke in 1.18.
I ported them to use ResourceLoader, but this is not a good solution yet because of bug
31676 (the 32-stylesheet limit of IE,
) which IMHO is a very serious
time-bomb waiting to explode. I hope it makes it into "1.19wmf deployment" as
4. Some of our parser tag extensions had a bug, in that they didn't return a
value in the tag callback. (These tags had no visual display.) This didn't cause
problems in 1.17 and earlier, but in 1.18.0 it caused a UNIQ.....QINU string to render on
the page. I fixed our extensions to return the empty string, and the problem went away.
5. The removal of $wgMessageCache->addMessage() broke many extensions, some ours
and some from mediawiki.org
like SimpleForms. Some fixes just required use of the i18n
file. Our more difficult issue was that we were injecting system messages into articles to
add tracking categories. On advice from this list (thanks!), we used code patterned after
Parser::addTrackingCategory() to inject categories and it works fine, actually much better
than what we had.
6. The removal of ts_makeSortable() from wikibits.js threw off a bunch of our
render, and in extensions that create tables within dialogs. We left the problem unfixed
until I can understand the new jQuery UI way of doing things (jquery.ui.sortable.js).
7. Nearly 100% of our customizations to WikiEditor 1.17 broke in 1.18. We had
followed the documented rules on mediawiki.org
, using extensions, ResourceLoader, etc.,
and everything worked in 1.17. Nevertheless in 1.18, toolbars and menus disappeared in
module became undefined in others, even with proper dependencies. Some of these issues are
still not worked out, but most were fixed by a variety of changes.
8. Our MediaWiki:common.js stopped running on the login page. I realize this was a
security fix; it just took me by surprise. Fixed by writing a custom extension using the
hook UserLoginForm to inject the few lines of JS we needed, and I'm evaluating other
non-JS solutions for more security.
worked around this by using jQuery's "bind" function.
At this point, our test wiki is stable and I am not anticipating any further large issues,
so we should roll out in the next two weeks or so.
Thanks for reading, and I hope this helps someone,