How to Add a Custom Function to MediaWiki « planetOzh

Recently, I wanted to add some dynamic content to a Mediawiki page : I wanted a project page to show how many lines of code the project currently had, and therefore I wanted something like <linecount> to be converted into something special.

Piece of cake ? Piece of cake. Adding custom tags or custom complex functions to your wiki is really easy, and here is how it can be done.

Adding a custom tag

For example, let's create the HTML tag <ozh>. Declaring a custom HTML tags in Mediawiki is done in 3 steps :

1. Register a new function :
   < View plain text >

   php

   
   

   1. $wgExtensionFunctions[] = 'registerSampleTag';
   2. $wgExtensionCredits['parserhook'][] = array(
   3.     'name' => 'SampleTag',
   4.     'author' => 'Ozh',
   5.     'url' => 'http://planetozh.com/',
   6. );
2. Tell the wiki that this function will be triggered by tag <ozh>
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   php

   
   

   1. function registerSampleTag() {
   2.     global $wgParser;
   3.     $wgParser->setHook('ozh', 'printSampleTag');
   4. }
3. Define your special function that will take care of text enclosed in your new tag
   < View plain text >

   php

   
   

   1. function printSampleTag($input,$params) {
   2.     foreach ($params as $key=>$value) {
   3.         $args .= "<li>$key = *$value*</li>\n";
   4.     }
   5.     return('Text : '.$input.'<br/>Arguments :<ul>'.$args.'</ul>');
   6. }

Put these 3 functions in a file named for example sampleExtension.php in directory mediawiki/extensions, then edit mediawiki/LocalSettings.php and add the following at the end of the file, before the closing PHP tag ?> :

That's it. Now, whenever your write something like

it will output

Ok, not the most useful stuff, but you get the idea :)

Adding a custom complex function

Now, you want to create something more complex, for example you'd like a custom function adequately named ozh that would convert "{{ozh:34|Quake|PHP}}" converted into "is 34 years old, plays Quake and writes poor PHP".

Your custom function declaration goes through 3 similar steps :

So …

How simple was it ?

For the curious readers, adding a line count from a subversion project was done with a bash script like :

The script is run periodically via cron, and a custom tag <linecount> simply calls a function that returns file_get_content('/home/ozh/project/line.count');