3 This document describes how event hooks work in MediaWiki; how to add
4 hooks for an event; and how to run hooks for an event.
9 Something that happens with the wiki. For example: a user logs
10 in. A wiki page is saved. A wiki page is deleted. Often there are
11 two events associated with a single action: one before the code
12 is run to make the event happen, and one after. Each event has a
13 name, preferably in CamelCase. For example, 'UserLogin',
14 'ArticleSave', 'ArticleSaveComplete', 'ArticleDelete'.
17 A clump of code and data that should be run when an event
18 happens. This can be either a function and a chunk of data, or an
22 The function part of a hook.
26 Hooks allow us to decouple optionally-run code from code that is run
27 for everyone. It allows MediaWiki hackers, third-party developers and
28 local administrators to define code that will be run at certain points
29 in the mainline code, and to modify the data run by that mainline
30 code. Hooks can keep mainline code simple, and make it easier to
31 write extensions. Hooks are a principled alternative to local patches.
33 Consider, for example, two options in MediaWiki. One reverses the
34 order of a title before displaying the article; the other converts the
35 title to all uppercase letters. Currently, in MediaWiki code, we
36 would handle this as follows (note: not real code, here):
38 function showAnArticle($article) {
39 global $wgReverseTitle, $wgCapitalizeTitle;
41 if ($wgReverseTitle) {
42 wfReverseTitle($article);
45 if ($wgCapitalizeTitle) {
46 wfCapitalizeTitle($article);
49 # code to actually show the article goes here
52 An extension writer, or a local admin, will often add custom code to
53 the function -- with or without a global variable. For example,
54 someone wanting email notification when an article is shown may add:
56 function showAnArticle($article) {
57 global $wgReverseTitle, $wgCapitalizeTitle;
59 if ($wgReverseTitle) {
60 wfReverseTitle($article);
63 if ($wgCapitalizeTitle) {
64 wfCapitalizeTitle($article);
67 # code to actually show the article goes here
69 if ($wgNotifyArticle) {
70 wfNotifyArticleShow($article));
74 Using a hook-running strategy, we can avoid having all this
75 option-specific stuff in our mainline code. Using hooks, the function
78 function showAnArticle($article) {
80 if (wfRunHooks('ArticleShow', array(&$article))) {
82 # code to actually show the article goes here
84 wfRunHooks('ArticleShowComplete', array(&$article));
88 We've cleaned up the code here by removing clumps of weird,
89 infrequently used code and moving them off somewhere else. It's much
90 easier for someone working with this code to see what's _really_ going
91 on, and make changes or fix bugs.
93 In addition, we can take all the code that deals with the little-used
94 title-reversing options (say) and put it in one place. Instead of
95 having little title-reversing if-blocks spread all over the codebase
96 in showAnArticle, deleteAnArticle, exportArticle, etc., we can
97 concentrate it all in an extension file:
99 function reverseArticleTitle($article) {
103 function reverseForExport($article) {
107 The setup function for the extension just has to add its hook
108 functions to the appropriate events:
110 setupTitleReversingExtension() {
113 $wgHooks['ArticleShow'][] = 'reverseArticleTitle';
114 $wgHooks['ArticleDelete'][] = 'reverseArticleTitle';
115 $wgHooks['ArticleExport'][] = 'reverseForExport';
118 Having all this code related to the title-reversion option in one
119 place means that it's easier to read and understand; you don't have to
120 do a grep-find to see where the $wgReverseTitle variable is used, say.
122 If the code is well enough isolated, it can even be excluded when not
123 used -- making for some slight savings in memory and load-up
124 performance at runtime. Admins who want to have all the reversed
127 require_once('extensions/ReverseTitle.php');
129 ...to their LocalSettings.php file; those of us who don't want or need
130 it can just leave it out.
132 The extensions don't even have to be shipped with MediaWiki; they
133 could be provided by a third-party developer or written by the admin
138 A hook is a chunk of code run at some particular event. It consists of:
140 * a function with some optional accompanying data, or
141 * an object with a method and some optional accompanying data.
143 Hooks are registered by adding them to the global $wgHooks array for a
144 given event. All the following are valid ways to define hooks:
146 $wgHooks['EventName'][] = 'someFunction'; # function, no data
147 $wgHooks['EventName'][] = array('someFunction', $someData);
148 $wgHooks['EventName'][] = array('someFunction'); # weird, but OK
150 $wgHooks['EventName'][] = $object; # object only
151 $wgHooks['EventName'][] = array($object, 'someMethod');
152 $wgHooks['EventName'][] = array($object, 'someMethod', $someData);
153 $wgHooks['EventName'][] = array($object); # weird but OK
155 When an event occurs, the function (or object method) will be called
156 with the optional data provided as well as event-specific parameters.
157 The above examples would result in the following code being executed
158 when 'EventName' happened:
161 someFunction($param1, $param2)
163 someFunction($someData, $param1, $param2)
166 $object->onEventName($param1, $param2)
168 $object->someMethod($param1, $param2)
169 # object with method and data
170 $object->someMethod($someData, $param1, $param2)
172 Note that when an object is the hook, and there's no specified method,
173 the default method called is 'onEventName'. For different events this
174 would be different: 'onArticleSave', 'onUserLogin', etc.
176 The extra data is useful if we want to use the same function or object
177 for different purposes. For example:
179 $wgHooks['ArticleSaveComplete'][] = array('ircNotify', 'TimStarling');
180 $wgHooks['ArticleSaveComplete'][] = array('ircNotify', 'brion');
182 This code would result in ircNotify being run twice when an article is
183 saved: once for 'TimStarling', and once for 'brion'.
185 Hooks can return three possible values:
187 * true: the hook has operated successfully
188 * "some string": an error occurred; processing should
189 stop and the error should be shown to the user
190 * false: the hook has successfully done the work
191 necessary and the calling function should skip
193 The last result would be for cases where the hook function replaces
194 the main functionality. For example, if you wanted to authenticate
195 users to a custom system (LDAP, another PHP program, whatever), you
198 $wgHooks['UserLogin'][] = array('ldapLogin', $ldapServer);
200 function ldapLogin($username, $password) {
205 Returning false makes less sense for events where the action is
206 complete, and will normally be ignored.
210 A calling function or method uses the wfRunHooks() function to run
211 the hooks related to a particular event, like so:
217 if (wfRunHooks('ArticleProtect', array(&$this, &$wgUser))) {
218 # protect the article
219 wfRunHooks('ArticleProtectComplete', array(&$this, &$wgUser));
224 wfRunHooks() returns true if the calling function should continue
225 processing (the hooks ran OK, or there are no hooks to run), or false
226 if it shouldn't (an error occurred, or one of the hooks handled the
227 action already). Checking the return value matters more for "before"
228 hooks than for "complete" hooks.
230 Note that hook parameters are passed in an array; this is a necessary
231 inconvenience to make it possible to pass reference values (that can
232 be changed) into the hook code. Also note that earlier versions of
233 wfRunHooks took a variable number of arguments; the array() calling
234 protocol came about after MediaWiki 1.4rc1.
236 ==Events and parameters==
238 This is a list of known events and parameters; please add to it if
239 you're going to add events to the MediaWiki code.
241 'AbortLogin': Return false to cancel account login.
242 $user: the User object being authenticated against
243 $password: the password being submitted, not yet checked for validity
244 &$retval: a LoginForm class constant to return from authenticateUserData();
245 default is LoginForm::ABORTED. Note that the client may be using
246 a machine API rather than the HTML user interface.
248 'AbortNewAccount': Return false to cancel account creation.
249 $user: the User object about to be created (read-only, incomplete)
250 $message: out parameter: error message to display on abort
252 'AddNewAccount': after a user account is created
253 $user: the User object that was created. (Parameter added in 1.7)
255 'AlternateEdit': before checking if an user can edit a page and
256 before showing the edit form ( EditPage::edit() ). This is triggered
258 $EditPage : the EditPage object
260 'ArticleDelete': before an article is deleted
261 $article: the article (object) being deleted
262 $user: the user (object) deleting the article
263 $reason: the reason (string) the article is being deleted
265 'ArticleDeleteComplete': after an article is deleted
266 $article: the article that was deleted
267 $user: the user that deleted the article
268 $reason: the reason the article was deleted
270 'ArticleInsertComplete': After an article is created
271 $article: Article created
272 $user: User creating the article
274 $summary: Edit summary/comment
275 $isMinor: Whether or not the edit was marked as minor
276 $isWatch: (No longer used)
277 $section: (No longer used)
278 $flags: Flags passed to Article::doEdit()
279 $revision: New Revision of the article
281 'ArticleProtect': before an article is protected
282 $article: the article being protected
283 $user: the user doing the protection
284 $protect: boolean whether this is a protect or an unprotect
285 $reason: Reason for protect
286 $moveonly: boolean whether this is for move only or not
288 'ArticleProtectComplete': after an article is protected
289 $article: the article that was protected
290 $user: the user who did the protection
291 $protect: boolean whether it was a protect or an unprotect
292 $reason: Reason for protect
293 $moveonly: boolean whether it was for move only or not
295 'ArticleSave': before an article is saved
296 $article: the article (object) being saved
297 $user: the user (object) saving the article
298 $text: the new article text
299 $summary: the article summary (comment)
304 'ArticleSaveComplete': After an article has been updated
305 $article: Article modified
306 $user: User performing the modification
308 $summary: Edit summary/comment
309 $isMinor: Whether or not the edit was marked as minor
310 $isWatch: (No longer used)
311 $section: (No longer used)
312 $flags: Flags passed to Article::doEdit()
313 $revision: New Revision of the article
315 'ArticleSaveComplete': after an article is saved
316 $article: the article (object) saved
317 $user: the user (object) who saved the article
318 $text: the new article text
319 $summary: the article summary (comment)
324 wfRunHooks( 'ArticleSaveComplete', array( &$this, &$wgUser, $text, $summary, $flags & EDIT_MINOR, null, null, &$flags, $revision ) );
326 'ArticleUndeleted': When one or more revisions of an article are restored
327 $title: Title corresponding to the article restored
328 $create: Whether or not the restoration caused the page to be created
329 (i.e. it didn't exist before)
331 'ArticleViewHeader': Before the parser cache is about to be tried for article viewing.
332 &$pcache: whether to try the parser cache or not
333 &$outputDone: whether the output for this page finished or not
335 'AuthPluginSetup': update or replace authentication plugin object ($wgAuth)
336 Gives a chance for an extension to set it programattically to a variable class.
337 &$auth: the $wgAuth object, probably a stub
339 'AutoAuthenticate': called to authenticate users on external/environmental means
340 $user: writes user object to this parameter
342 'BadImage': When checking against the bad image list
343 $name: Image name being checked
344 &$bad: Whether or not the image is "bad"
346 Change $bad and return false to override. If an image is "bad", it is not
347 rendered inline in wiki pages or galleries in category pages.
349 'BeforeGalleryFindFile': before an image is fetched for a gallery
350 &$gallery,: the gallery object
351 &$nt: the image title
352 &$time: image timestamp
354 'BeforeParserFetchTemplateAndtitle': before a template is fetched by Parser
355 &$parser: Parser object
356 &$title: title of the template
357 &$skip: skip this template and link it?
358 &$id: the id of the revision being parsed
360 'BeforeParserMakeImageLinkObj': before an image is rendered by Parser
361 &$parser: Parser object
362 &$nt: the image title
363 &$skip: skip this image and link it?
364 &$time: the image timestamp
366 'BeforeParserrenderImageGallery': before an image gallery is rendered by Parser
367 &$parser: Parser object
368 &$ig: ImageGallery object
370 'BlockIp': before an IP address or user is blocked
371 $block: the Block object about to be saved
372 $user: the user _doing_ the block (not the one being blocked)
374 'BlockIpComplete': after an IP address or user is blocked
375 $block: the Block object that was saved
376 $user: the user who did the block (not the one being blocked)
378 'BookInformation': Before information output on Special:Booksources
379 $isbn: ISBN to show information for
380 $output: OutputPage object in use
382 'ContributionsToolLinks': Change tool links above Special:Contributions
384 $title: User page title
385 &$tools: Array of tool links
387 'CustomEditor': When invoking the page editor
388 $article: Article being edited
389 $user: User performing the edit
391 Return true to allow the normal editor to be used, or false
392 if implementing a custom editor, e.g. for a special namespace,
395 'DiffViewHeader': called before diff display
396 $diff: DifferenceEngine object that's calling
397 $oldRev: Revision object of the "old" revision (may be null/invalid)
398 $newRev: Revision object of the "new" revision
400 'EditPage::attemptSave': called before an article is
401 saved, that is before insertNewArticle() is called
402 &$editpage_Obj: the current EditPage object
404 'EditFormPreloadText': Allows population of the edit form when creating new pages
405 &$text: Text to preload with
406 &$title: Title object representing the page being created
408 'EditPage::showEditForm:fields': allows injection of form field into edit form
409 &$editor: the EditPage instance for reference
410 &$out: an OutputPage instance to write to
411 return value is ignored (should always return true)
413 'EditFilter': Perform checks on an edit
414 $editor: Edit form (see includes/EditPage.php)
415 $text: Contents of the edit box
416 $section: Section being edited
417 &$error: Error message to return
419 Return false to halt editing; you'll need to handle error messages, etc. yourself.
420 Alternatively, modifying $error and returning true will cause the contents of $error
421 to be echoed at the top of the edit form as wikitext. Return true without altering
422 $error to allow the edit to proceed.
424 'EditSectionLink': Override the return value of Linker::editSectionLink()
425 $skin: Skin rendering the UI
426 $title: Title being linked to
427 $section: Section to link to
429 $result: Result (alter this to override the generated links)
431 'EditSectionLinkForOther': Override the return value of Linker::editSectionLinkForOther()
432 $skin: Skin rendering the UI
433 $title: Title being linked to
434 $section: Section to link to
435 $hint: Anchor title/tooltip attributes
437 $result: Result (alter this to override the generated links)
439 'EmailConfirmed': When checking that the user's email address is "confirmed"
440 $user: User being checked
441 $confirmed: Whether or not the email address is confirmed
442 This runs before the other checks, such as anonymity and the real check; return
443 true to allow those checks to occur, and false if checking is done.
445 'EmailUser': before sending email from one user to another
446 $to: address of receiving user
447 $from: address of sending user
448 $subject: subject of the mail
449 $text: text of the mail
451 'EmailUserComplete': after sending email from one user to another
452 $to: address of receiving user
453 $from: address of sending user
454 $subject: subject of the mail
455 $text: text of the mail
457 'FetchChangesList': When fetching the ChangesList derivative for a particular user
458 &$user: User the list is being fetched for
459 &$skin: Skin object to be used with the list
460 &$list: List object (defaults to NULL, change it to an object instance and return
461 false override the list derivative used)
463 'FileUpload': When a file upload occurs
464 $file : Image object representing the file that was uploaded
466 'GetInternalURL': modify fully-qualified URLs used for squid cache purging
467 $title: Title object of page
468 $url: string value as output (out parameter, can modify)
469 $query: query options passed to Title::getInternalURL()
471 'GetLocalURL': modify local URLs as output into page links
472 $title: Title object of page
473 $url: string value as output (out parameter, can modify)
474 $query: query options passed to Title::getLocalURL()
476 'GetFullURL': modify fully-qualified URLs used in redirects/export/offsite data
477 $title: Title object of page
478 $url: string value as output (out parameter, can modify)
479 $query: query options passed to Title::getFullURL()
481 'ImageOpenShowImageInlineBefore': Call potential extension just before showing the image on an image page
482 $imagePage: ImagePage object ($this)
485 'InitPreferencesForm': called at the end of PreferencesForm's constructor
486 $form: the PreferencesForm
487 $request: the web request to initialized from
489 'InternalParseBeforeLinks': during Parser's internalParse method before links but
490 after noinclude/includeonly/onlyinclude and other processing.
491 &$this: Parser object
492 &$text: string containing partially parsed text
493 &$this->mStripState: Parser's internal StripState object
495 'isValidPassword': Override the result of User::isValidPassword()
496 $password: Desired password
497 &$result: Set this and return false to override the internal checks
498 $user: User the password is being validated for
500 'LinksUpdateConstructed': At the end of LinksUpdate() is contruction.
501 &$linksUpdate: the LinkUpdate object
503 'LoginAuthenticateAudit': a login attempt for a valid user account either succeeded or failed.
504 No return data is accepted; this hook is for auditing only.
505 $user: the User object being authenticated against
506 $password: the password being submitted and found wanting
507 $retval: a LoginForm class constant with authenticateUserData() return value (SUCCESS, WRONG_PASS, etc)
509 'LogPageValidTypes': action being logged. DEPRECATED: Use $wgLogTypes
510 &$type: array of strings
512 'LogPageLogName': name of the logging page(s). DEPRECATED: Use $wgLogNames
513 &$typeText: array of strings
515 'LogPageLogHeader': strings used by wfMsg as a header. DEPRECATED: Use $wgLogHeaders
516 &$headerText: array of strings
518 'LogPageActionText': strings used by wfMsg as a header. DEPRECATED: Use $wgLogActions
519 &$actionText: array of strings
521 'MarkPatrolled': before an edit is marked patrolled
522 $rcid: ID of the revision to be marked patrolled
523 $user: the user (object) marking the revision as patrolled
524 $wcOnlySysopsCanPatrol: config setting indicating whether the user
525 needs to be a sysop in order to mark an edit patrolled
527 'MarkPatrolledComplete': after an edit is marked patrolled
528 $rcid: ID of the revision marked as patrolled
529 $user: user (object) who marked the edit patrolled
530 $wcOnlySysopsCanPatrol: config setting indicating whether the user
531 must be a sysop to patrol the edit
533 'MathAfterTexvc': after texvc is executed when rendering mathematics
534 $mathRenderer: instance of MathRenderer
535 $errmsg: error message, in HTML (string). Nonempty indicates failure
536 of rendering the formula
538 'OutputPageBeforeHTML': a page has been processed by the parser and
539 the resulting HTML is about to be displayed.
540 $parserOutput: the parserOutput (object) that corresponds to the page
541 $text: the text that will be displayed, in HTML (string)
543 'PageHistoryBeforeList': When a history page list is about to be constructed.
544 $article: the article that the history is loading for
546 'PageHistoryLineEnding' : right before the end <li> is added to a history line
547 $row: the revision row for this line
548 $s: the string representing this parsed line
550 'PageRenderingHash': alter the parser cache option hash key
551 A parser extension which depends on user options should install
552 this hook and append its values to the key.
553 $hash: reference to a hash key string which can be modified
555 'ParserTestTables': alter the list of tables to duplicate when parser tests
556 are run. Use when page save hooks require the presence of custom tables
557 to ensure that tests continue to run properly.
558 &$tables: array of table names
560 'PersonalUrls': Alter the user-specific navigation links (e.g. "my page,
561 my talk page, my contributions" etc).
563 &$personal_urls: Array of link specifiers (see SkinTemplate.php)
564 &$title: Title object representing the current page
566 'PingLimiter': Allows extensions to override the results of User::pingLimiter()
567 &$user : User performing the action
568 $action : Action being performed
569 &$result : Whether or not the action should be prevented
570 Change $result and return false to give a definitive answer, otherwise
571 the built-in rate limiting checks are used, if enabled.
573 'PreferencesUserInformationPanel': Add HTML bits to user information list in preferences form
574 $form : PreferencesForm object
575 &$html : HTML to append to
577 'RawPageViewBeforeOutput': Right before the text is blown out in action=raw
578 &$obj: RawPage object
579 &$text: The text that's going to be the output
581 'RenderPreferencesForm': called at the end of PreferencesForm::mainPrefsForm
582 $form: the PreferencesForm
583 $out: output page to render to, probably $wgOut
585 'ResetPreferences': called at the end of PreferencesForm::resetPrefs
586 $form: the PreferencesForm
587 $user: the User object to load preferences from
589 'SavePreferences': called at the end of PreferencesForm::savePreferences;
590 returning false prevents the preferences from being saved.
591 $form: the PreferencesForm
592 $user: the User object to save preferences to
593 $message: change this to set an error message (ignored if the hook does notreturn fals)
595 'SearchUpdate': Prior to search update completion
597 $namespace : Page namespace
599 $text : Current text being indexed
601 'SiteNoticeBefore': Before the sitenotice/anonnotice is composed
602 &$siteNotice: HTML returned as the sitenotice
603 Return true to allow the normal method of notice selection/rendering to work,
604 or change the value of $siteNotice and return false to alter it.
606 'SiteNoticeAfter': After the sitenotice/anonnotice is composed
607 &$siteNotice: HTML sitenotice
608 Alter the contents of $siteNotice to add to/alter the sitenotice/anonnotice.
610 'SkinTemplateOutputPageBeforeExec': Before SkinTemplate::outputPage() starts page output
611 &$sktemplate: SkinTemplate object
612 &$tpl: Template engine object
614 'SpecialContributionsBeforeMainOutput': Before the form on Special:Contributions
617 'TitleMoveComplete': after moving an article (title)
620 $user: user who did the move
621 $pageid: database ID of the page that's been moved
622 $redirid: database ID of the created redirect
624 'UnknownAction': An unknown "action" has occured (useful for defining
627 $article: article "acted on"
629 'UnwatchArticle': before a watch is removed from an article
631 $article: article object to be removed
633 'UnwatchArticle': after a watch is removed from an article
634 $user: user that was watching
635 $article: article object removed
637 'UploadForm:initial': before the upload form is generated
638 $form: UploadForm object
639 You might set the member-variables $uploadFormTextTop and
640 $uploadFormTextAfterSummary to inject text (HTML) either before
641 or after the editform.
643 'UploadForm:BeforeProcessing': at the beginning of processUpload()
644 $form: UploadForm object
645 Lets you poke at member variables like $mUploadDescription before the
648 'UploadVerification': additional chances to reject an uploaded file
649 string $saveName: destination file name
650 string $tempName: filesystem path to the temporary file for checks
651 string &$error: output: HTML error to show if upload canceled by returning false
653 'UploadComplete': Upon completion of a file upload
654 $image: Image object representing the file that was uploaded
656 'UserCan': To interrupt/advise the "user can do X to Y article" check
657 $title: Title object being checked against
658 $user : Current user object
659 $action: Action being checked
660 $result: Pointer to result returned if hook returns false. If null is returned,
661 UserCan checks are continued by internal code
663 'UserCreateForm': change to manipulate the login form
664 $template: SimpleTemplate instance for the form
666 'UserLoginComplete': after a user has logged in
667 $user: the user object that was created on login
669 'UserLoginForm': change to manipulate the login form
670 $template: SimpleTemplate instance for the form
672 'UserLogout': before a user logs out
673 $user: the user object that is about to be logged out
675 'UserLogoutComplete': after a user has logged out
676 $user: the user object _after_ logout (won't have name, ID, etc.)
678 'UserRights': After a user's group memberships are changed
679 $user : User object that was changed
680 $add : Array of strings corresponding to groups added
681 $remove: Array of strings corresponding to groups removed
683 'WatchArticle': before a watch is added to an article
684 $user: user that will watch
685 $article: article object to be watched
687 'WatchArticleComplete': after a watch is added to an article
688 $user: user that watched
689 $article: article object watched
691 'UnwatchArticleComplete': after a watch is removed from an article
692 $user: user that watched
693 $article: article object that was watched
695 'UserGetRights': Called in User::getRights()
696 $user: User to get rights for
697 &$rights: Current rights
699 'UserEffectiveGroups': Called in User::getEffectiveGroups()
700 $user: User to get groups for
701 &$groups: Current effective groups
703 'CategoryPageView': before viewing a categorypage in CategoryPage::view
704 $catpage: CategoryPage instance
706 'SkinTemplateContentActions': after building the $content_action array right
707 before returning it, see Content_action.php in
708 the extensions/examples/ directory
709 ( http://svn.wikimedia.org/viewvc/mediawiki/trunk/extensions/examples/ )
710 for a demonstration of how to use this hook.
711 $content_actions: The array of content actions
713 'BeforePageDisplay': Called just before outputting a page (all kinds of,
714 articles, special, history, preview, diff, edit, ...)
715 Can be used to set custom CSS/JS
716 $out: OutputPage object
718 'ShowRawCssJs': Customise the output of raw CSS and JavaScript in page views
719 $text: Text being shown
720 $title: Title of the custom script/stylesheet page
721 $output: Current OutputPage object
723 'AjaxAddScript': Called in output page just before the initialisation
724 of the javascript ajax engine. The hook is only called when ajax
725 is enabled ( $wgUseAjax = true; ).
727 More hooks might be available but undocumented, you can execute
728 ./maintenance/findhooks.php to find hidden one.