MediaWiki source code details

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computing: software: MediaWiki: code details

[edit] Notes

[edit] Some significant globals

Note: In PHP, you have to declare a global variable before you can use it; otherwise PHP will assume you want a new local variable by the same name.

  • $wgUser is the user object, defined in User.php (declare it like this: global $wgUser;)
    • $wgUser->getGroups() returns an array of strings where each string is a group to which the user belongs, e.g. for a sysop/bureaucrat, $groups[0] would be "bureaucrat" if you did this: $groups = $wguser->getGroups();
    • If you need to know membership in implicit groups such as "user" and "*", use $wgUser->getEffectiveGroups()
    • Use $wgUser->isAllowed(action) to find out if the user has permission for a particular action. Default permissions are in DefaultSettings.php, overridable in LocalSettings.php, and documented here

The function outputPage in SkinTemplate.php references a large number of globals, many of which may be significant.

[edit] Where the Nav Links Come From

In SkinTemplate.php, function outputPage seems to be building a massive hierarchical array ($tpl) of all the various components needed to display a wiki page, which is then converted to HTML (etc.) by the code in the applicable (skin name).php file. Significant lines for generating the navigation links would appear to be these: 

$tpl->set( 'navigation_urls', $this->buildNavigationUrls() );
$tpl->set( 'nav_urls', $this->buildNavUrls() );

Both of these return arrays which are added to the $tpl array. Function buildNavigationUrls() uses $wgNavigationLinks as a source for its list of links. Function buildNavUrls(), however, has a hard-coded list; it's not clear what the relationship is between those two.

$wgNavigationLinks is defined in DefaultSettings.php, and presumably can be redefined in LocalSettings.php (if, say, you wanted to add more lines to the "navigation" linkbox): 

$wgNavigationLinks = array ( array( 'text'=>'mainpage',
'href'=>'mainpage' ), array( 'text'=>'portal',
'href'=>'portal-url' ), array( 'text'=>'currentevents',
'href'=>'currentevents-url' ), array( 'text'=>'recentchanges',
'href'=>'recentchanges-url' ), array( 'text'=>'randompage',
'href'=>'randompage-url' ), array( 'text'=>'help',
'href'=>'helppage' ), array( 'text'=>'sitesupport',
'href'=>'sitesupport-url' ),
);

Each of the strings (except "text" and "href") refers to a value which is settable via the wiki, e.g. the value of "mainpage" can be set by editing the contents of MediaWiki:Mainpage. From there, I was able to figure out how to Add a New Navigation Box.

[edit] How A Page is Built

(From Woozle 21:59, 15 Jun 2005 (EDT).)

  • Everything obviously starts with index.php
  • For the purpose of displaying a page (not saving changes or doing anything else), this calls $wgArticle->view(), in Article.php (line 699)
  • $wgArticle->view() appears to be able to provide a few other formats besides the regular view (including difference engine and displaying redirections as subtitles), but I'm ignoring that for now
  • $wgOut seems to be the object which accumulates text to be output. It is created in Setup.php:
    • $wgOut = new OutputPage();
  • OutputPage() is defined in OutputPage.php
  • After being created, $wgOut accumulates output via various class methods:
  • ...and then it does these two lines:
    • $this->viewUpdates(); (found at line 1926 -- doesn't do much)
    • wfProfileOut( $fname );
  • It's not clear whether the navbar has already been pulled in by the time we hit viewUpdates -- possibly transformBuffer does it? The comment makes it sound like that, but the name "transformBuffer" in that case is not very descriptive. The code in there should probably be examined.
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