Extension:Multi-Category Search

The Multi-Category Search extension allows users to find pages that are included in several specified categories at once (pages that intersect multiple categories). By default a user can specify up to 5 categories to intersect, and optionally up to 3 categories to be completely excluded from search. Upon many requests, drop-down lists were introduced in version 1.3, and since version 1.5 it's now possible to fill drop-down lists automatically with subcategories of some parent category. Extension was first released on January 23, 2008‎.

Purpose and usage
The extension is indispensable, if you need, for example, to find all articles about american comedy movies released in 1990 on your cinema-related wiki. In this case you just need to go to Special:MultiCategorySearch special page, specify three categories there: "USA films", "Comedy films" and "1990 films", and click on search button. That's it - you get the list of movies.

Configuration
General configuration settings are set in five variables in the beginning of MultiCategorySearch_body.php file. Here are sample settings and their description.

Maximum number of categories that user can search for: Maximum number of categories that user can exclude from search: When set to true, drop-down lists with predefined categories are shown on the search form. Categories for drop-down lists must be predefined in showDropdownLists function in the end of MultiCategorySearch_body.php file. When set to true, inserts MediaWiki:Edittools at the bottom of the search form. Edittools allow user to insert special characters in an easy way. Remember, that EditTools require Extension:CharInsert to be installed and AJAX to be enabled (global $wgUseAjax variable must be set to true in LocalSettings.php file). Default HTTP method of passing parameters. Change it to 'get' if required.

Transclusion
By transclusion the multi-category search results could be dynamically shown on some other page. Transclusion format is:

Version history

 * 1.65 — Update to suit MediaWiki 1.21.
 * 1.64 — Multiple transclusions on one page have been enabled.
 * 1.63 — Update to suit MediaWiki 1.19. Drop-down lists configuration system has been simplified.
 * 1.62 — Update to suit MediaWiki 1.18.
 * 1.61 — Minor bugfix.
 * 1.6 — Localized messages caching system has been updated.
 * 1.5 — An option to fill drop-down lists automatically with subcategories of some parent category has been added. Minor bugfix.
 * 1.4 — A patch by William Moore has been applied, allowing Special:MultiCategorySearch page to be transcluded.
 * 1.38 — Minor bugfix.
 * 1.37 — Minor changes.
 * 1.36 — Minor bugfixes.
 * 1.35 — Minor internal improvements.
 * 1.34 — Minor internal improvements.
 * 1.33 — Listing of articles, which are not included in specified categories, is now available even if no category was selected to search for.
 * 1.31 — Minor bugfix.
 * 1.3 — Optional drop-down list selection was added.
 * 1.21 — Edittools file has been added; database table prefixes recognition was enabled.
 * 1.01 — Minor bugfix.

Localization

 * Spanish messages by José Zarco
 * German messages by Astrid Kuhr
 * French messages by Thierry Giroux Veilleux
 * Dutch messages by Nanda Jansen
 * Russian messages by Iaroslav Vassiliev
 * Turkish messages by Helmut Oberdiek
 * Hebrew messages by Avner Pinchover
 * Polish messages by Dawid Kamola
 * Italian messages by Cristian Filagrossi
 * Japanese messages by Kouichi Nishizawa
 * Czech messages by Vojtěch Zlámal

Contacts
If you would like to report a bug, request a feature, or if you could help with localization (extension messages translation), please, send me a letter to [mailto:codedriller@gmail.com codedriller@gmail.com]. By the way, if you need advanced bot functionality for your wiki, take a look at free DotNetWikiBot Framework, that I maintain.