View source for Manual:Magic words

<languages/>
{{Magic words}}
{{advanced user manual}}
[[File:MediaWiki-extensions-icon.svg|125px|alt=<translate><!--T:1--> MediaWiki extensions</translate>|right]]

<translate><!--T:79--> '''Magic words''' are strings of text that MediaWiki links to specific functions or return values, such as current date and time, page titles, site information, and more.</translate>
<translate><!--T:80--> They can be thought of as special commands or variables that allow dynamic content generation and interaction with the MediaWiki software during page rendering.</translate>

<translate><!--T:81--> From a technical standpoint, magic words map a range of wiki text strings to a unique internal identifier (ID), which is then associated with a particular function.</translate>
<translate><!--T:82--> This ID directs MediaWiki to execute a corresponding operation or return a specific value. Both '''{{<tvar name=1>ll|Manual:Variables</tvar>|variables}}''' (which output dynamic values) and '''{{<tvar name=2>ll|Manual:Parser functions</tvar>|parser functions}}''' (which perform operations or conditional logic) make use of this mapping technique.</translate>

<translate><!--T:50--> All text mapped to that ID will be replaced with the return value of the function.</translate>
<translate><!--T:51--> The mapping between the text strings and the ID is stored in the variable <tvar name=magicWords><code>$magicWords</code></tvar> in a file that can be loaded using <tvar name=1>{{wg|ExtensionMessagesFiles}}</tvar>.</translate>

<translate>
<!--T:3-->
The default magic words are implemented in <tvar name=CoreParserFunctions>{{ll|Manual:CoreParserFunctions.php|CoreParserFunctions.php}}</tvar>.

== How magic words work == <!--T:4-->

<!--T:5-->
Whenever MediaWiki finds text between double braces (<tvar name=4><code><nowiki>{{</nowiki>XXX ...}}</code></tvar>) it must decide whether XXX is a [[<tvar name=1>Special:MyLanguage/Manual:Variables</tvar>|variable]], [[<tvar name=2>Special:MyLanguage/Manual:Parser functions</tvar>|parser function]], or [[<tvar name=3>Special:MyLanguage/Help:Templates</tvar>|template]].  To do so, it asks a series of questions:
</translate>

#<translate><!--T:6--> '''Does it have an associated magic word ID?''' As a first step in resolving markup of the form <tvar name=1><code><nowiki>{{XXX...}}</nowiki></code></tvar>, MediaWiki attempts to translate ''<tvar name=2>XXX</tvar>'' to a magic word ID. The translation table is defined by <tvar name=magicWords><code>$magicWords</code></tvar>. </translate>
#*<translate><!--T:7--> If no magic word ID is associated with ''<tvar name=2>XXX</tvar>'', ''<tvar name=2>XXX</tvar>'' is presumed to be a [[<tvar name=1>Special:MyLanguage/Help:Templates</tvar>|template]].</translate>
#:<br/>
#<translate><!--T:8--> '''Is it a variable?''' If a magic word ID <em>is</em> found, MediaWiki next checks to see if it has any parameters.</translate> 
#*<translate><!--T:9--> If no parameters are found, MediaWiki checks to see if the magic word ID has been declared as a variable ID.</translate> <translate><!--T:44--> To check this, it retrieves the list of magic words serving by calling <tvar name=1><code>MagicWord::getVariableIDs()</code></tvar>.</translate> <translate><!--T:45--> This method gets its list of variable IDs from a hard coded list of variable IDs (see <tvar name=1>{{ll|Help:Variables}}</tvar>) and from a list of custom variable IDs provided by all functions attached to the hook <tvar name=2>{{ll|Manual:Hooks/MagicWordwgVariableIDs|MagicWordwgVariableIDs}}</tvar>.</translate>
#**<translate><!--T:10--> If the magic word ID has been classified as a variable, MediaWiki calls the <tvar name=1>{{ll|Manual:Hooks/ParserGetVariableValueSwitch|ParserGetVariableValueSwitch}}</tvar> function to get the value associated with the variable name.</translate>
#:<br/>
#<translate><!--T:11--> '''Is it a parser function?''' If there are any parameters or if the magic word ID is missing from the list of variable magic word IDs, then MediaWiki assumes that the magic word is a [[<tvar name=1>Special:MyLanguage/Manual:Parser functions</tvar>|parser function]] or [[<tvar name=2>Special:MyLanguage/Help:Templates</tvar>|template]].</translate> <translate><!--T:74--> If the magic word ID is found in the list of declared parser functions, it is treated as a parser function and rendered using the function named <tvar name=2><code>$renderingFunctionName</code></tvar>.</translate> <translate><!--T:75--> Otherwise, it is presumed to be a template.</translate>

<translate>
== Defining magic words == <!--T:12-->
</translate>
{{note
| 2 = reminder
| 1 = <translate><!--T:83--> '''When defining or translating magic words, adhere to established conventions'''.</translate>

<translate>
<!--T:57-->
By convention:
</translate>

* <translate><!--T:58--> The magic words called variables are capitalised, case-sensitive, and do not have space characters.</translate>
* <translate><!--T:72--> Parser functions are prefixed with a hash sign (<tvar name="1"><nowiki>#</nowiki></tvar>), are case insensitive, and do not include space characters.</translate>

<translate>
<!--T:59-->
This is however a convention and one not consistently applied (for historic reasons).
</translate>

* <translate><!--T:60--> Variables do not have spaces in English, but some translations of variables in other languages '''do''' have spaces.</translate>
* <translate><!--T:61--> Variables generally are capitalised and case-sensitive, but some parser functions also use this convention.</translate>
* <translate><!--T:62--> Some parser functions start with a hash sign, but some do not.</translate>

<translate><!--T:68--> Where possible the conventions for defining or translating magic words should be followed.</translate>
<translate><!--T:69--> Magic words are higher in priority than templates, so any magic word defined, will block the usage of that defined name as a template.</translate>
<translate><!--T:70--> Following the conventions avoids creating additional potential naming collisions.</translate>
}}

<translate>
<!--T:13-->
For magic words to do their magic we must define two things:

<!--T:63-->
* a mapping between wiki text and a magic word ID</translate>
<translate>
<!--T:64-->
* a mapping between a magic word ID and some PHP function that interprets the magic word.

=== Mapping wiki text to magic word IDs === <!--T:14-->
</translate>
<translate><!--T:15--> The variable <tvar name=magicWords><code>$magicWords</code></tvar> is used to associate each magic word ID with a language-dependent array that describes all the text strings that mapped to the magic word ID.</translate>
<translate><!--T:39--> Important: This only sets up the back end i18n mapping, you still have to write other code to make MediaWiki use the magic word for anything.</translate>
<translate><!--T:73--> Also, make sure that you initialise <tvar name="1"><code>$magicWords</code></tvar> as an empty array before adding language-specific values or you will get errors when trying to load the magic word and will need to rebuild your localisation cache before it will work.</translate>

<translate><!--T:16--> The first element of this array is an integer flag indicating whether or not the magic word is case sensitive. The remaining elements are a list of text that should be associated with the magic word ID.  If the case sensitive flag is 0, any case variant of the names in the array will match.  If the case sensitive flag is 1, only exact case matches will be associated with the magic word ID.</translate>
<translate><!--T:40--> Thus the format is <tvar name=1><code>$magicWords['en'] = [ 'InternalName' => [ 0, 'NameUserTypes', 'AdditionalAliasUserCanType' ] ];</code></tvar></translate>

<translate>
<!--T:17-->
This association is created by <tvar name=magicWords><code>$magicWords</code></tvar> in a file registered using <tvar name=1>{{Wg|ExtensionMessagesFiles}}</tvar>.
</translate>

<translate><!--T:18--> In the example below, a Spanish MediaWiki installation will associate the magic word ID <tvar name=1><code>MAG_CUSTOM</code></tvar> with "personalizado", "custom", "PERSONALIZADO", "CUSTOM" and all other case variants.</translate>
<translate><!--T:65--> In an English MediaWiki only "custom" in various case combinations will be mapped to <tvar name=1><code>MAG_CUSTOM</code></tvar>:</translate>

<translate>
<!--T:19-->
File <tvar name=1><code>Example.i18n.magic.php</code></tvar>:
</translate>

<syntaxhighlight lang="php">
<?php

$magicWords = [];

$magicWords['en'] = [
	'MAG_CUSTOM' => [ 0, 'custom' ],
];

$magicWords['es'] = [
	'MAG_CUSTOM' => [ 0, 'personalizado' ],
];
</syntaxhighlight>

<translate>
<!--T:43-->
In part of the <tvar name=1><code>{{ll|Manual:Extension registration|extension.json}}</code></tvar> file:
</translate>

<syntaxhighlight lang="json">
"ExtensionMessagesFiles": {
	"ExampleMagic": "Example.i18n.magic.php"
}
</syntaxhighlight> 

<translate>
<!--T:21-->
Note that "ExampleMagic" is a different to the key you would use for a plain internationalisation file (normally just the title of the extension, i.e. "Example"). "Magic" has been appended deliberately so one does not overwrite the other.

==== In inline PHP ==== <!--T:46-->
</translate>
<translate><!--T:47--> You can associate magic words inline in PHP rather than through a i18n file.</translate>
<translate><!--T:48--> This is useful when defining hooks in <tvar name=1><code>{{ll|Manual:LocalSettings.php|LocalSettings.php}}</code></tvar> but should not be done in extensions.</translate>

<syntaxhighlight lang="php">
$contentLanguage = MediaWiki\MediaWikiServices::getInstance()->getContentLanguage();
$contentLanguage->mMagicExtensions['wikicodeToHtml'] = ['MAG_CUSTOM', 'custom'];
</syntaxhighlight> 

<translate>
=== Associating a magic word ID with a PHP function === <!--T:22-->

<!--T:23-->
The mechanism for associating magic word IDs with rendering functions depends on whether the magic word will be used as a [[<tvar name=1>Special:MyLanguage/Manual:Parser functions</tvar>|parser function]] or a [[<tvar name=2>Special:MyLanguage/Manual:Variables</tvar>|variable]]. For more information, please see:
</translate>

* {{ll|Manual:Parser functions}}
* {{ll|Manual:Variables}}

<translate>
=== Localisation === <!--T:27-->
</translate>

:''<translate><!--T:28--> See [[<tvar name=1>Special:MyLanguage/Help:Magic words#Localisation</tvar>|Help:Magic words#Localisation]] for help.</translate>''

<translate>
<!--T:29-->
You can read more on definition and usage of magic words for localisation at <tvar name=1>{{ll|Manual:Messages API}}</tvar>, [[<tvar name=2>Special:MyLanguage/Manual:Language#Namespaces</tvar>|Manual:Language#Namespaces]]; [[<tvar name=3>Special:MyLanguage/Help:System message#Avoid_.7B.7BSITENAME.7D.7D_in_messages</tvar>|<nowiki>Avoid {{SITENAME}} in messages</nowiki>]].

==Behavior switches (double underscore magic words)== <!--T:34-->
</translate>
<translate><!--T:35--> Behavior switches are a special type of magic word. They can be recognised by their use of double underscores (rather than double braces).</translate>
<translate><!--T:66--> Example:</translate>
<code><nowiki>__NOTOC__</nowiki></code>

<translate><!--T:36--> These magic words typically do not output any content, but instead change the behavior of a page and/or set a page property.</translate>
<translate><!--T:52--> These magic words are listed in <tvar name=1>{{phpi|MagicWordFactory::mDoubleUnderscoreIDs}}</tvar> and also at [[<tvar name=behaviorSwitches>Special:MyLanguage/Help:Magic words#Behavior switches</tvar>|Help:Magic words#Behavior switches]].</translate>
<translate><!--T:53--> The effect of most standard behavior switches is defined in <tvar name=1>{{phpi|Parser::handleDoubleUnderscore()}}</tvar>.</translate>
<translate><!--T:54--> If no specific effect is defined, the magic word will simply set a page property in the <tvar name=1><code>page_props</code></tvar> table.</translate>
<translate><!--T:67--> This can also be checked later by testing if <tvar name=1><syntaxhighlight lang="php" inline>$parser->getOutput()->getPageProperty( 'MAGIC_WORD' )</syntaxhighlight></tvar> is null or the empty string</translate>

<translate>
=== Custom behavior switch === <!--T:55-->

<!--T:56-->
Here is an example extension implementing a custom <tvar name=1><code><nowiki>__CUSTOM__</nowiki></code></tvar> behaviour switch
</translate>

'''MyExt/extension.json''' - <translate><!--T:71--> This is minimal, a real extension would fill out more fields.</translate>
<syntaxhighlight lang="json">
{
	"name": "MyExt",
	"type": "parserhook",
    "AutoloadNamespaces": {
		"MediaWiki\\Extension\\MyExt\\": "includes/"
	},
	"Hooks": {
		"GetDoubleUnderscoreIDs": "main",
		"ParserAfterParse": "main" 
	},
	"HookHandlers": {
		"main": {
			"class": "MediaWiki\\Extension\\MyExt\\Hooks"
		}
	},
	"ExtensionMessagesFiles": {
		"MyExtMagic": "MyExt.i18n.magic.php"
	},
	"manifest_version": 2
}
</syntaxhighlight>
'''MyExt/MyExt.i18n.magic.php'''
<syntaxhighlight lang="php">
<?php
$magicWords = [];
$magicWords['en'] = [
	'MAG_CUSTOM' => [ 0, '__CUSTOM__' ],
];
</syntaxhighlight>

'''MyExt/includes/Hooks.php'''
<syntaxhighlight lang="php">
<?php

namespace MediaWiki\Extension\MyExt;

use MediaWiki\Hook\GetDoubleUnderscoreIDsHook;
use MediaWiki\Hook\ParserAfterParseHook;
use MediaWiki\Parser\Parser;
use MediaWiki\Parser\StripState;

class Hooks implements GetDoubleUnderscoreIDsHook, ParserAfterParseHook {
	/**
	 * @param string[] &$doubleUnderscoreIDs
	 * @return bool|void
	 */
	public function onGetDoubleUnderscoreIDs( &$ids ) {
		$ids[] = 'MAG_CUSTOM';
	}

	/**
	 * @param Parser $parser
	 * @param string &$text
	 * @param StripState $stripState
	 * @return bool|void
	 */
	public function onParserAfterParse( $parser, &$text, $stripState ) {
		if ( $parser->getOutput()->getPageProperty( 'MAG_CUSTOM' ) !== null ) {
			// <translate nowrap><!--T:84--> Do behavior switching here ...</translate>
			// <translate nowrap><!--T:85--> e.g. If you wanted to add some JS, you would do $parser->getOutput()->addModules( [ 'moduleName' ]</translate> );
		}
	}
}
</syntaxhighlight>

<translate>
==See also== <!--T:37-->
</translate>
*{{ll|Help:Magic words}} - <translate><!--T:38--> List of Variables like <tvar name=1><code><nowiki>{{PAGENAME}}</nowiki></code></tvar> and <tvar name=2><code><nowiki>{{SERVER}}</nowiki></code></tvar></translate>
*{{ll|Manual:MagicWord.php}}

{{Extension development}}

[[Category:Customization techniques{{#translation:}}|{{PAGENAME}}]]
[[Category:Magic words{{#translation:}}|{{PAGENAME}}]]