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From mediawiki.org
MediaWiki extensions manual
Release status: stable
Implementation Parser function
Description Adds a parser function to test if the current page is in some category
Author(s) Brian Wolff (Bawolfftalk)
Latest version 3.0.0 (2016-12-22)
MediaWiki 1.25+
License GNU General Public License 2.0 or later
  • $wgPageInCatUseAccuratePreview
Quarterly downloads 2 (Ranked 134th)
Translate the PageInCat extension if it is available at translatewiki.net
This extension might sometimes not account for categories that got added to the current page immediately after save on MediaWiki 1.27 and later (due to change 1846e2dc15e957c55). If that does happen, it will work properly after purging the page.

The PageInCat extension adds a parser function that is similar to the {{#ifexist:...}} function from ParserFunctions extension.


It works as follows

{{#incat:Some category|what to do if current page is in category|what to do if current page is not in category}}

. It also supports the #incategory, #ifpageincat and #ifpageincategory functions.

Conditional category inclusion

Adding things like {{#incat:Foo||[[category:Foo]]}} (Page is a member of category Foo only if it is not a member of category Foo) is generally a bad idea (duh!). This could cause the page to alternate being in and not in the category. More generally, putting any sort of category link inside a {{#incat:...}} may cause unexpected behaviour since the extension can't tell if its in the category until after parsing the entire page. In general, for the purposes of {{#incat:...}}, we consider the categories present the first time parsing the page as the categories the page is in.

If this sort of situation is detected during a preview, the following warning is presented at the top of the page:

Warning: The category Some category was detected incorrectly by {{#incat:...}}, and as a result this preview may be incorrect. This can be caused by including categories inside of {{#incat:...}} statements, and may result in inconsistent display.


  • Download and move the extracted PageInCat folder to your extensions/ directory.
    Developers and code contributors should install the extension from Git instead, using:cd extensions/
    git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/PageInCat
  • Add the following code at the bottom of your LocalSettings.php file:
    wfLoadExtension( 'PageInCat' );
  • Configure as required.
  • Yes Done – Navigate to Special:Version on your wiki to verify that the extension is successfully installed.


Defaults to "true". Controls if to use more accurate previews (aka use the categories that are in the wiki-text you are previewing instead of the last saved revision). May cause previews to take twice as much time as they normally would (This includes previewing things not using #incat functions). If this is set to false, previews will often have {{#incat:..}} being evaluated incorrectly, but once the page is saved, they will be evaluated correctly.
Not directly a configuration parameter of this extension, but limits the number of times you can use #incat (and other expensive parser functions) in a page (Doing #incat twice for the same category only counts as one usage). This defaults to 100, which should be more than enough.

See also[edit]

  • Extension:ParserFunctions (For more general conditional constructs)
  • Extension:CategoryTests Can test if another page is in some category. (Did not know this extension existed when I wrote this one. The main difference seems to be that PageInCat will always try to use categories from the current revision, while CategoryTests may sometimes use the categories from the previous revision, which could result in unexpected page content)