Parser function extensions

A "parser function" is a template-like construct that returns a value based on at least one unnamed parameter, separated from the function name by a colon [:]. There may be more parameters, as well; like those of ordinary templates, these additional parameters are each preceded by a "pipe" [|]. In the case of a hash character [#] at the start of the function name (which prevents collision with namespaces and interwiki prefixes), this may or may not be considered part of the name. If it is considered part of the name, the syntax is of the form

{{functionname: argument 1 | argument 2 | argument 3...}}

If the caller has no arguments to provide the parser function, then the form is simply {{functionname:}} or, when a hash character applies (as is normally the case) then the form is {{#functionname:}}. If the trailing colon is not supplied, then functionname is not recognized by the parser.

Arguments cannot directly contain "|" or "}}" except as part of the code of a template call, parser function call, variable, link or image, but they can contain them arbitrarily using a template, e.g., m:Template:!, or a parser function.

The code can specify whether the function name is case-sensitive.

The separation of the arguments from each other is with "|", and from the function name is with the first ":" The expansion of each of these pieces is standard, as in Special:ExpandTemplates (which is a good place to experiment, by the way, if you are learning this stuff) and is beyond the control of the parser function itself.

However, everything else can be different for each parser function, including:

• whether an argument is just a value, or of the form parname = parvalue, or whatever
• if applicable, whether parameter names are case-sensitive

Syntax prescribed by a parser function extension

In view of the above, it is advantageous to make an extension such that the syntax to be used in an argument does not contain the pipe character "|" or double braces (more specifically, double closing braces "}}" ). This, in spite of the fact that a pipe character would otherwise seem a suitable symbol for, e.g., a choice or union (see, e.g., [1]). Allowing such codes is harmless if an alternative code is also allowed, e.g. "\" for "|".

Table of functions

extension	function	MediaWiki version
built-in	lc	1.7+
built-in	uc	1.7+
built-in	lcfirst	1.7+
built-in	ucfirst	1.7+
built-in	urlencode	1.7+
built-in	anchorencode	1.8+
built-in	localurl	1.7+
built-in	fullurl	1.7+
built-in	#language	1.7+
built-in	#special	1.9+
built-in	#tag	1.12+
Extension:ParserFunctions (usage )	#expr	1.19+
Extension:ParserFunctions (usage )	#ifexpr	1.19+
Extension:ParserFunctions (usage )	#if	1.19+
Extension:ParserFunctions (usage )	#ifeq	1.19+
Extension:ParserFunctions (usage )	#ifexist	1.19+
Extension:ParserFunctions (usage )	#rel2abs	1.19+
Extension:ParserFunctions (usage )	#titleparts	1.19+
Extension:ParserFunctions (usage )	#switch	1.19+
Extension:ParserFunctions (usage )	#time	1.19+
Extension:AddScriptCss	#addscript	Archived
Extension:Arrays	#arraydefine	1.23+
Extension:Arrays	#arraydiff	1.23+
Extension:Arrays	#arrayindex	1.23+
Extension:Arrays	#arrayintersect	1.23+
Extension:Arrays	#arraymerge	1.23+
Extension:Arrays	#arrayprint	1.23+
Extension:Arrays	#arrayreset	1.23+
Extension:Arrays	#arraysearch	1.23+
Extension:Arrays	#arraysearcharray	1.23+
Extension:Arrays	#arraysize	1.23+
Extension:Arrays	#arrayslice	1.23+
Extension:Arrays	#arraysort	1.23+
Extension:Arrays	#arraytohash	1.23+
Extension:Arrays	#arrayunion	1.23+
Extension:Arrays	#arrayunique	1.23+
Extension:Arrays	#hashtoarray	1.23+
Extension:Attachments	#attach	1.31+
Extension:Attachments	#exturl	1.31+
Extension:Babel	#babel	1.30+
Extension:CSS	#css	1.25+
Extension:Coordinate	#coordinate	Archived
Extension:Counter	#+	1.15+
Extension:Data	#data	Archived
Extension:Data	#sort	Archived
Extension:DynamicFunctions	#arg	Archived
Extension:DynamicFunctions	#ip	Archived
Extension:DynamicFunctions	#rand	Archived
Extension:DynamicFunctions	#skin	Archived
Extension:DynamicPageList (third-party)	#dpl	Archived
Extension:DynamicPageList3	#dpl	1.39+
Extension:ExpandAfter	#expandafter (deprecated , see: #tag)	Archived
Extension:ForeachFunction	#foreachx	Archived
Extension:ForeachFunction	#foreachy	Archived
Extension:HasCategory	#ifhascat	Archived
Extension:HideNamespace	#hidens	Archived
Extension:HideNamespace	#unhidens	Archived
Extension:ImageLink	#img (old: #imagelink, deprecated )	Archived
Extension:Infobox Data Capture	#dataentry	Archived
Extension:Infobox Data Capture	#listsplit	Archived
Extension:InterWikiLinkManager	#iwl	Archived
Extension:KeyValue	#keyvalue	Archived
Extension:Labeled Section Transclusion	#lst	1.25+
Extension:Labeled Section Transclusion	#lstx	1.25+
Extension:Labeled Section Transclusion	#lsth	1.25+
Extension:LoopFunctions	#for	1.23+
Extension:LoopFunctions	#foreach	1.25+
Extension:Loops	#while	1.25+
Extension:Loops	#dowhile	1.25+
Extension:Loops	#forargs	1.25+
Extension:Loops	#fornumargs	1.25+
Extension:Loops	#loop	1.25+
Extension:Maps	#geocode	1.27+
Extension:Maps	#display_map	1.27+
Extension:Maps	#display_point	1.27+
Extension:Maps	#coordinates	1.27+
Extension:Maps	#distance	1.27+
Extension:MediaFunctions	#media..	1.23+
Extension:PageAfterAndBefore	#pagebefore	Archived
Extension:PageAfterAndBefore	#pageafter	Archived
Extension:PageAfterAndBefore	#firstpage	Archived
Extension:PageAfterAndBefore	#lastpage	Archived
Extension:PageFunctions	#pagetitle	Archived
Extension:PageFunctions	#pagesubtitle	Archived
Extension:PageFunctions	#pageexists	Archived
Extension:PageFunctions	#varset	Archived
Extension:PageFunctions	#varget	Archived
Extension:PageFunctions	#varcapset	Archived
Extension:PageFunctions	#cshow	Archived
Extension:PageFunctions	#varaset	Archived
Extension:PageFunctions	#varaget	Archived
Extension:ParserFunctions (extended)	#expr (extended)	Archived
Extension:ParserFunctions (extended)	#ifexpr (extended)	Archived
Extension:ParserFunctions (extended)	#min	Archived
Extension:ParserFunctions (extended)	#max	Archived
Extension:ParserFunctions (extended)	#if	Archived
Extension:ParserFunctions (extended)	#ifeq	Archived
Extension:ParserFunctions (extended)	#ifexist	Archived
Extension:ParserFunctions (extended)	#rel2abs	Archived
Extension:ParserFunctions (extended)	#switch	Archived
Extension:ParserFunctions (extended)	#time	Archived
Extension:Pipe Escape	#!	1.23+
Extension:QPoll	#qpuserchoice	Archived
Extension:RegexTools	#regex	Archived
Extension:RegexTools	#regex_vars	Archived
Extension:Scribunto	#invoke
Extension:SecureProperties	#pg	Archived
Extension:SecureProperties	#ps	Archived
Extension:SecureProperties	#pf	Archived
Extension:SecureProperties	#gg	Archived
Extension:SecureProperties	#gs	Archived
Extension:Semantic MediaWiki	#ask	1.27+
Extension:Semantic MediaWiki	#concept	1.27+
Extension:Semantic MediaWiki	#info	1.27+
Extension:Semantic MediaWiki	#show	1.27+
Extension:Semantic MediaWiki	#set	1.27+
Extension:StringFunctions	#len	1.7+
Extension:StringFunctions	#pos	1.7+
Extension:StringFunctions	#rpos	1.7+
Extension:StringFunctions	#sub	1.7+
Extension:StringFunctions	#pad	1.7+
Extension:StringFunctions	#replace	1.7+
Extension:StringFunctions	#explode	1.7+
Extension:StringFunctions	#urlencode	1.7+
Extension:StringFunctions	#urldecode	1.7+
Extension:TreeAndMenu	#tree	1.23+
Extension:TreeAndMenu	#menu	1.23+
Extension:Variables	#vardefine	1.29+
Extension:Variables	#vardefineecho	1.29+
Extension:Variables	#var	1.29+
Extension:Variables	#varexists	1.29+
Extension:Variables	#var_final	1.29+
Extension:Wikibase Client	#property
Extension:Wikibase Client	#statements

See also

• Help:Magic words
• Category:Parser function extensions
• Writing parser functions (software development)
• Parser functions for Wikibase (the extensions that enables Wikidata): d:Wikidata:How to use data on Wikimedia projects