Extension:RandomSelection

MediaWiki extensions manual - list

RandomSelection Release status: stable
Implementation	Tag
Description	Displays a random option from the given set.
Author(s)	Ross McClure (Algorithmtalk)
Last version	2.1.6 (2012-09-02)
MediaWiki	1.12+
Database changes	no
License	No license specified
Download	see below Changelog
Example	Example
Tags <choose> <option> <choicetemplate>
Hooks used ParserFirstCallInit
Check usage and version matrix

The RandomSelection extension allows for randomly-generated content inside your wiki; e.g. rotating images, random greetings, etc.

Usage

To choose between one or more options, simply place each option inside an <option> tag, like so:

<choose>
<option>This is the first choice.</option>
<option>This is the second choice.</option>
<option>And so on...</option>
</choose>

From each set of <choose> tags, precisely one <option> tag will be selected at random, and its contents shown. Anything can be placed inside of option tags: links, images, even templates. Note, however, that template arguments will not be expanded due to bugzilla:2257.

Weight

If you'd like some options to be shown more often than others, you can add weight to the option tags, like so:

<choose>
<option weight="2">This option will be shown twice as often as a normal option.</option>
<option>By default, options have a weight of 1.</option>
<option weight="1.5">This option also has a weight of 1.  Fractional portions are ignored.</option>
</choose>

You can also have what is placed inside the option tags be sent as an argument to a template, e.g.:

Choice templates

<choose>
<option>Template:Featured article/Elephant</option>
<option>Template:Featured article/Giraffe</option>
<option>Template:Featured article/Rhinoceros</option>
<choicetemplate>PageWithEditButton</choicetemplate>
</choose>

You could then create a Template:PageWithEditButton with these contents:

[{{canonicalurl:{{{1}}}|action=edit}} Edit] {{{{{1}}}}}

This is useful if you want to set up randomly rotating featured articles and have an edit button to allow the user to edit the featured article blurbs.

Installation

1. Save the source code into a file called RandomSelection.php
2. Create a folder called RandomSelection in the extensions directory of your installation (.../extensions/) and move the file RandomSelection.php into it
3. Add following line in LocalSettings.php:

   require_once( "$IP/extensions/RandomSelection/RandomSelection.php" );
   

4. Installation may now be verified at Special:Version

Source Code

The code in this page will only work in MediaWiki 1.12 and above. (Alternate version for 1.5 and above).

RandomSelection.php

<?php
/**
 * RandomSelection -- randomly displays one of the given options.
 * Usage: <choose><option>A</option><option>B</option></choose>
 * Optional parameter: <option weight="3"> == 3x weight given
 *
 * @file RandomSelection.php
 * @ingroup Extensions
 * @version 2.1.6
 * @date 17 January 2010
 * @author Ross McClure <https://www.mediawiki.org/wiki/User:Algorithm>
 * @link https://www.mediawiki.org/wiki/Extension:RandomSelection Documentation
 */
 
if( !defined( 'MEDIAWIKI' ) ) {
        die( "This is not a valid entry point to MediaWiki.\n" );
}
 
$wgHooks['ParserFirstCallInit'][] = 'wfRandomSelection';
 
$wgExtensionCredits['parserhook'][] = array(
        'name' => 'RandomSelection',
        'version' => '2.1.6',
        'author' => 'Ross McClure',
        'description' => 'Displays a random option from the given set',
        'url' => 'https://www.mediawiki.org/wiki/Extension:RandomSelection',
);
 
function wfRandomSelection( &$parser ) {
        $parser->setHook( 'choose', 'renderChosen' );
        return true;
}
 
function renderChosen( $input, $argv, $parser ) {
        # Prevent caching
        $parser->disableCache();
 
        # Parse the options and calculate total weight
        $len = preg_match_all(
                "/<option(?:(?:\\s[^>]*?)?\\sweight=[\"']?([^\\s>]+))?"
                        . "(?:\\s[^>]*)?>([\\s\\S]*?)<\\/option>/",
                $input,
                $out
        );
 
        # Find any references to a surrounding template
        preg_match_all(
                "/<choicetemplate(?:(?:\\s[^>]*?)?\\sweight=[\"']?([^\\s>]+))?"
                        . "(?:\\s[^>]*)?>([\\s\\S]*?)<\\/choicetemplate>/",
                $input,
                $outTemplate
        );
        $r = 0;
        for( $i = 0; $i < $len; $i++ ) {
                if( strlen( $out[1][$i] ) == 0 ) {
                        $out[1][$i] = 1;
                } else {
                        $out[1][$i] = intval( $out[1][$i] );
                }
                $r += $out[1][$i];
        }
 
        # Choose an option at random
        if( $r <= 0 ) {
                return '';
        }
        $r = mt_rand( 1, $r );
        for( $i = 0; $i < $len; $i++ ) {
                $r -= $out[1][$i];
                if( $r <= 0 ) {
                        $input = $out[2][$i];
                        break;
                }
        }
 
        # Surround by template if applicable
        if ( isset ( $outTemplate[2][0] ) ) {
                $input = '{{' . $outTemplate[2][0] . '|' . $input . '}}';
        }
 
        # Parse tags and return
        return $parser->recursiveTagParse( $input );
}

Changelog

• 2012-09-02 -- Added <choicetemplate> functionality
• 2007-12-10 -- Updated for compatibility with MW 1.12's new parser model
• 2008-02-23 -- Minor bugfix
• 2008-05-08 -- Bugfix
• 2008-07-01 -- Use ParserFirstCallInit hook if it's available
• 2009-09-30 -- Doxygen comments added + minor tweaks
• 2010-01-17 -- dropped backwards compatibility with old MediaWikis as per r55838 and made the extension work under PHP 5.3+

Tested

• MW 1.19.x -  OK --Leucosticte (talk) 21:58, 2 September 2012 (UTC)
• MW 1.16.x -  OK --[[kgh]] (talk) 22:10, 7 June 2012 (UTC)
• MW 1.18.x -  OK --[[kgh]] (talk) 18:37, 7 June 2012 (UTC)

See also

• Extension:Blurb