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Writing a MediaWiki Gravatars template

This is a tutorial for MediaWiki users who want to learn how to create and use templates.

One day, I was looking for a MediaWiki extension to include a Gravatar (globally recognized avatar) in my user page on one of my MediaWiki installations. I did find an extension, but I thought it to be no better than writing a template myself.

A MediaWiki template

In a MediaWiki installation, if you find yourself repeating yourself in a lot of pages, you can turn the repetitive content into a template. This template can then be included in any page where you’d otherwise duplicate the content. In fact, you can include any page, but most templates will live in a separate namespace: Template.

To include a template, put the template name inside double curly braces, like this: {{My template}}. For templates inside the Template namespace (most templates), you can omit the namespace part. This means that if your template page name is Template:My template, you will call your template as in the previous example ({{My template}}).

Template parameters

Parameterization is a fancy word for what programmers do when they don’t want a function to return the same value on each invocation. They add parameters to the function. MediaWiki templates support parameters.

If you have a template called Template:My template which contains “I say this very often, but not {{{1}}}.“, you can invoke it with “{{My template|quite often enough}}“, you’ll get the text “I say this very often but not quite often enough“.

Template parameters are preceded by a pipe symbol (“|”). If you add more parameters, each in turn has to be preceded by the same symbol. Whitespace (even newlines) may be used before or after the pipe to increase readability.

To indicate where in the template you want the parameter value to appear, triple curly braces are used with the number of the parameter inside.

Named parameters

When your template accepts a lot of parameters, you might find it convenient to name the parameters instead of numbering them. Named and numbered parameters can be mixed (but the numbered parameters must come first):

{{Fruit|apple|color=red}}

Referencing the named parameter in the template is as easy as referencing a numbered parameter:

When I need vitamins, I can eat an {{{1}}}. This fruit is {{{color}}}.

Default parameter values

Parameters can be made optional, by adding a default value:

When I need vitamins, I can eat an {{{1|orange}}}. This fruit is {{{color|orange}}}.

Now, you can call the Fruit template with no arguments if you just want an orange.

Gravatar API

Gravatars are retreived by using a very simple URL API. The URL is constructed using the MD5-sum of your email address:

echo -n $EMAIL|md5sum
77eca8beb1df91ca21e6c781e62630f8

http://www.gravatar.com/avatar/77eca8beb1df91ca21e6c781e62630f8

Optional parameters can be given in the URL. For now, I’m only interested in s (for size). This defaults to 80 pixels, but I want a bigger image:

http://www.gravatar.com/avatar/77eca8beb1df91ca21e6c781e62630f8?s=200

A working Gravatar template

On my Hardwood Investments Wiki, I have made a template that is meant to be used on a user page (such as my own) to display a Gravatar similarly to how captioned images are normally formatted:

<noinclude>
This template shows a Gravatar for the given e-mail address belonging to a given MD5 sum.

== Example ==

<pre>
{{User Gravatar|41165a7e7126d616a0ae0762e00718e2}}
</pre>

</noinclude><includeonly><div style="margin: 0 0 1em 1em; float: right; border: 1px solid #ccc; background-color: #f9f9f9; padding: 3px;">
<div style="border: 1px solid #ccc;">
http://www.gravatar.com/avatar/{{{1}}}?s=200.jpg
</div>{{PAGENAME}}
</div></includeonly>

This template introduces a two new concepts: the <noinclude> section is only used when viewing the template page and the <includeonly> section is used only when viewing the page that includes the template; {{PAGENAME}} is a magic word that is used to display the username as the image caption.

Now that I’ve demonstrated a practical application of MediaWiki templates, I can finally publish this draft. 🙂


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