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Help:Magic words

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Magic words are strings of text that MediaWiki associates with a return value or function, such as time, site details, or page names.

Examples include

  • __NOTOC__ - Hides the table of contents (short for "NO Table Of Contents").
  • __NOINDEX__ - Tell search engines not to index the page
  • {{CURRENTYEAR}} - Current year: 2019
  • {{NUMBEROFARTICLES}} - Number of pages in content namespaces: 8,351
  • {{FULLPAGENAME}} - Namespace and page title: Help:Magic words
  • {{PAGENAME}} - Page title: Magic words

There are many, many more, for a wide range of date & time, site statistics & page name data.

For full details, see mw:Help:Magic words.

Parser functions[edit]

A parser function is a "magic word" that takes a parameter. This allows more complex functions and calculations to be performed.

Use with care[edit]

Please use with care, as needed. Parser function code can easily scare away editors. So...

  • Use in templates, not directly in pages.
  • If you're experimenting with parser function code, especially complex code, use your userspace. E.g. put the template at [[User:Yourname/templatename]], and insert the template using {{User:Yourname/templatename}}. If it proves useful, it can be moved to template space later.
  • If your documentation explains how your template works, this helps future editors of the template.


Standard parser functions[edit]

The main use of the standard parser functions are url encoding, date formatting and case formatting. E.g.

https://www.appropedia.org/Page_name outputs a page's url. {{fullurl:passive solar}}https://www.appropedia.org/Passive_solar

For full details, see mw:Help:Magic words #Parser functions.


Extra parser functions[edit]

The Parser Functions extension is enabled on Appropedia, giving another 11 functions, including if and switch functions, to perform certain logical operations. Examples include:

  • #expr evaluates an expression as true (1) or false (0). For logical inputs, any non-zero number is true, and 0 is false
    • {{#expr: 1.5*2=3 }} → 1
    • {{#expr: 1.5*2=400 }} → 0
    • {{#expr: 1 and 0 }} → 0
    • {{#expr: 1 or 0 }} → 1
  • #if is a little counterintuitive. It returns a true value if the first parameter is 'non-empty'. If it is empty or only whitespace, it evaluates to false. A mathematical expression is treated as a string and evaluates to true even if the expression itself is false. The second parameter is the 'true' output, and the third and final parameter is the 'false' output:
    • {{#if: blah | rhino | unicorn }} → rhino
    • {{#if: | rhino | unicorn }} → unicorn
    • {{#if: 0 | yes | no }} → yes
  • #ifexpr evaluates a mathematical expression and returns the second parameter string if true, and the third (and last) parameter string if false. E.g.:
    • {{#ifexpr: 1 < 0 | true | false}} → false
    • {{#ifexpr: 1+1=2 | blue | red}} → blue
  • #switch displays the value of one of its parameters, e.g. {{#switch: baz | foo = Foo | baz = Baz | Bar }}

For full details, see mw:Help:Extension:ParserFunctions.