Editing Manual/Extensions

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<translate>
<!--T:3-->
An '''extension''' lets you customise how MediaWiki looks and works.
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* <translate><!--T:5--> System administrators can [[<tvar name=1>#Installing an extension</tvar>|install]] (or remove) extensions on the MediaWiki installations that they manage.</translate> 
* <translate><!--T:6--> Developers can [[<tvar name=1>#Developing extensions</tvar>|write new extensions]] or contribute to existing extensions.</translate>

{{Note|inline=0|type=info
|1=<translate><!--T:13--> While some extensions are maintained by MediaWiki developers, others are developed by third parties and may be unmaintained.</translate> <translate><!--T:14--> As a result, many extensions may contain bugs—including, in some cases, security vulnerabilities.</translate> <translate><!--T:15--> Not all extensions are compatible with every version of MediaWiki, and they may not function reliably when used together.</translate>

<translate><!--T:152--> Use extensions at your own risk, particularly those tagged as insecure.</translate> <translate><!--T:116--> If an extension requires patches to the core software, make sure to back up your database beforehand to minimize the risk of breaking your wiki.</translate>
}}

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== Selecting extensions == <!--T:130-->

=== Bundled extensions === <!--T:137-->

<!--T:138-->
Several extensions are  as standard.
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<translate><!--T:139--> These extensions should generally be of high utility, perform efficiently, be stable, be well-written, and have no known major security issues.</translate>
<translate><!--T:140--> They should also be compatible with the latest versions of MediaWiki, and with each other (i.e. one extension shouldn't block the functions of another).</translate>
<translate><!--T:141--> A bundled extension may have a dependency on one or more other extensions, as long as those are also bundled.</translate>

<translate><!--T:142--> Site admins get these automatically when installing or upgrading MediaWiki.</translate>
<translate><!--T:143--> When upgrading MediaWiki, any extension upgrades will be automatically applied as well.</translate>
<translate><!--T:144--> Site admins may choose to uninstall any of these, if they wish.</translate>

<translate><!--T:145--> There are open, ongoing discussions about which extensions should be part of this group.</translate>
<translate><!--T:146--> You can .</translate>
<translate><!--T:147--> Extensions will be bundled once the developers reach a consensus to do so.</translate>

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<!--T:148-->
An extension may be removed from bundling if its functionality is merged into , it is replaced by an alternative, or in the unlikely event of any unsolvable major security vulnerabilities being discovered.

=== Browsing extensions === <!--T:18-->

<!--T:19-->
Browse <tvar name=1></tvar>, or <tvar name=2></tvar> to see the full range of extensions that are available.

=== Checking installed extensions === <!--T:22-->
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<translate><!--T:149--> Which extensions are active on an instance of MediaWiki can be checked by accessing the <tvar name=1>[[Special:Version]]</tvar> page, and scrolling down to the heading ''Installed extensions'' (anchor <tvar name=2><code>#mw-version-ext</code></tvar>).</translate>
<translate><!--T:24--> For example, [[<tvar name=1>Special:Version#mw-version-ext</tvar>|these extensions]] are installed on this wiki, and [[<tvar name=2>W:Special:Version#mw-version-ext</tvar>|these extensions]] are active in the English Wikipedia.</translate>

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=== Popular extensions === <!--T:119-->
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<translate><!--T:124--> <tvar name="1"></tvar> counts wikis that extensions are installed on.</translate>
<translate><!--T:125--> This represents actual installations and not just downloads (i.e. it queries the wiki's APIs), but it is also (as of 2023) not completely up-to-date.</translate>
<translate><!--T:126--> It also doesn't count installations on private wikis.</translate>

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== Installing an extension == <!--T:25-->
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: ''<translate><!--T:131--> For further guidance, see also <tvar name=1></tvar></translate>''

<translate><!--T:26--> MediaWiki is ready to accept extensions just after [[<tvar name=man>Special:MyLanguage/Manual:Installation</tvar>|installation]] is finished.</translate> 
<translate><!--T:27--> To add an extension follow these steps:</translate>

# '''<translate><!--T:28--> Before you start</translate>'''
#: <translate><!--T:29--> Many extensions provide instructions designed for installation using Unix commands.</translate> <translate><!--T:30--> You require shell access (SSH) to enter these commands listed on the extension help pages.</translate>
# '''<translate><!--T:31--> Download your extension</translate>'''
#: <translate><!--T:32--> [[<tvar name=special>Special:ExtensionDistributor</tvar>|Extension Distributor]] helps you to select and download most of the popular extensions.</translate>
#: <translate><!--T:33--> Extensions are usually distributed as modular packages.</translate> <translate><!--T:34--> They generally go in their own subdirectory of <tvar name=IP><code>/extensions/</code></tvar>.</translate> <translate><!--T:35--> A list of extensions stored in the Wikimedia [[<tvar name=gerrit>Special:MyLanguage/Gerrit</tvar>|Git repository]] is located at <tvar name=extensions>[[phab:diffusion/MEXT/browse/master/|git:mediawiki/extensions]]</tvar>.</translate> <translate><!--T:36--> Some extensions [[<tvar name=cat>Special:MyLanguage/Category:Extensions which host their code in-wiki</tvar>|don't use version control]] and are not recommended.</translate>
#: <translate><!--T:37--> Some extensions are also available in [[<tvar name=1>Special:MyLanguage/Software bundles</tvar>|bundles]], <tvar name=composer></tvar> or [[<tvar name=2>Special:MyLanguage/Comparison of extensions in distributions</tvar>|package repositories]].</translate>
#: <translate><!--T:127--> It's recommended to read the <tvar name=1>README</tvar> file before installation.</translate> <translate><!--T:128--> It usually contains important info about configuration.</translate>
# '''<translate><!--T:38--> Install your extension</translate>'''
#: <translate><!--T:39--> At the end of the <tvar name=LocalSettings><code></code></tvar> file, add:</translate>
#: <syntaxhighlight lang="php">
wfLoadExtension( 'ExtensionName' );
</syntaxhighlight>
#: <translate><!--T:40--> This line forces the PHP interpreter to read the extension file, and thereby make it accessible to MediaWiki.</translate>
#: <translate><!--T:41--> Some extensions can conflict with maintenance scripts, for example if they directly access <tvar name=1><code>$_SERVER</code></tvar> (not recommended).</translate> <translate><!--T:42--> In this case, they can be wrapped in the conditional so maintenance scripts can still run.</translate>
#: <syntaxhighlight lang="php">
if ( !$wgCommandLineMode ) {
   wfLoadExtension ( 'ExtensionName' );
}
</syntaxhighlight>
#: <translate><!--T:43--> The maintenance script <tvar name=ImportDump></tvar> will fail for any extension which requires customised namespaces which is ''included'' inside the conditional above such as <tvar name=1></tvar>, <tvar name=2></tvar>.</translate>

: 
: {{Note|1=<translate><!--T:45--> While this installation procedure is sufficient for most extensions, some require a different installation procedure.</translate> <translate><!--T:46--> Check your extension's documentation for details.</translate>}}
: {{Note|1=<translate><!--T:47--> If you want to alter configuration variables in <tvar name=1><code>LocalSettings.php</code></tvar>, you have to do this typically '''after''' including the extension.</translate> <translate><!--T:48--> Otherwise defaults defined in the extension will overwrite your settings.</translate>}}

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=== Upgrading an extension === <!--T:51-->
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<translate><!--T:52--> Some extensions require to be updated whenever you update MediaWiki, while others work with multiple versions.</translate> 
<translate><!--T:53--> To upgrade to a new version of an extension:</translate>

# <translate><!--T:54--> Download the new version of the extension</translate>
# <translate><!--T:55--> Replace all the extension files in the <tvar name=1><code>extensions/ExtensionName</code></tvar> directory with the new files.</translate> <translate><!--T:56--> Do not remove the extension configuration present in <tvar name=1><code>LocalSettings.php</code></tvar></translate>
# <translate><!--T:57--> If the extension requires changes to the MediaWiki database, you will need to run the <tvar name=1></tvar> maintenance script.</translate> <translate><!--T:58--> Most extensions will mention if this script needs to be run or not.</translate> <translate><!--T:83--> (Perform backup of your data before executing the script).</translate> <translate><!--T:60--> If you don't have command line access, you can also use the [[<tvar name=man>Special:MyLanguage/Manual:Upgrading#Web_updater</tvar>|web updater]].</translate>

{{Note|1=<translate><!--T:63--> These instructions cover 99% of extensions.</translate> <translate><!--T:64--> If the specific extension you are upgrading has instructions that differ from these, you should probably follow the specific extension's instructions</translate>}}

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=== Uninstalling an extension === <!--T:65-->

<!--T:86-->
Remove the line from <tvar name=1><code>LocalSettings.php</code></tvar> with the extension name to uninstall it:
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<syntaxhighlight lang="php">
wfLoadExtension( 'ExtensionName' );
</syntaxhighlight>

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<!--T:87-->
* You must also remove any lines pertaining to the configuration of the extension.

== Developing extensions == <!--T:132-->
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<translate><!--T:133--> MediaWiki core provides several ways for extensions to change the behavior and appearance of a wiki.</translate>
<translate><!--T:134--> Various  give extensions flexibility to add features and functionality, such as displaying a special page or defining an API module.</translate>
<translate><!--T:135--> To get started, see the .</translate>
<translate><!--T:136--> Before writing a new extension, consider contributing to an  or helping with an .</translate>

<translate><!--T:150--> Users can also make a general request on Phabricator, and hope that your good idea is picked up by a developer.</translate>
<translate><!--T:151--> See <tvar name=1>https://phabricator.wikimedia.org/tag/mediawiki-extension-requests/</tvar></translate>

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== See also == <!--T:79-->
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* 
* 
* 
*  – <translate><!--T:82--> Information about translating extensions.</translate>
* [[Special:ExtensionDistributor]] – <translate><!--T:118--> Includes a list of the 15 most downloaded extensions in Wikimedia version control</translate>
* [https://extloc.toolforge.org/ extloc] – <translate><!--T:153--> Where are MediaWiki extensions deployed in Wikimedia production?</translate>
* [[API:Siteinfo#Extensions]]
* 
* 
* 
* 

[[Category:Customization techniques|Customization techniques]]
[[Category:Extension creation]]

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''Sample content adapted from [[mediawikiwiki:Manual:Extensions]] on mediawiki.org, licensed under [https://creativecommons.org/licenses/by-sa/4.0/ CC BY-SA 4.0].''