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,
https://bugzilla.wikimedia.org/show_bug.cgi?id=31676) which IMHO is a very
serious time-bomb waiting to explode. I hope it makes it into "1.19wmf
deployment" as planned.
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 JavaScript: we were using the function to sort on a different column than
the first one on 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 IE. Menus appeared multiple times instead of
once in Firefox. JavaScript objects in one 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.
9. The addHandler() function in JavaScript does not seem to work in IE8
anymore. We 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,
DanB
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