By MW in mediawiki — 16 Apr 2025

Mastering MediaWiki Templates: Creating Reusable Content Structures

Why Templates Matter in MediaWiki

Ever stared at a dozen pages that look almost identical, then spent an afternoon hunting down a stray bold‑tag or a missing reference? You’re not alone. In the wild world of wikis, repetition is a silent productivity killer. A well‑crafted template is like a Swiss‑army knife: it slices through redundancy, keeps style consistent, and lets you swap out a single piece of code to refresh a whole family of pages.

Getting Your Hands Dirty – The Basics

At its core a MediaWiki template is just a regular wiki page stored in the Template: namespace. Once you create Template:Infobox, you can sprinkle {{Infobox|title=My title|date=2025}} anywhere you like. The parser replaces the curly braces with the markup you defined.

Step‑by‑step (quick, not exhaustive)

Open a new page named Template:MyTemplate.
Write the skeleton of the content, using parameters like {{{1}}} or named ones like {{{title|default=Untitled}}}.
Save. Test on a sandbox page: {{MyTemplate|Hello world}}.

That’s it. But “it’s done” is a dangerous phrase—templates can grow into sophisticated, data‑aware components.

Beyond the Basics – Dynamic and Semantic Templates

When you need more than a static infobox, you start pulling in parser functions, conditional logic, and even semantic extensions. A typical “advanced” template might look like this:

{{#if:{{{image|}}}
|[[File:{{{image}}}|thumb|{{{alt|}}}]]
|}}
'''{{{title|Untitled}}}''' – {{#ifexpr: {{#time:U}} > {{#time:U|{{{expire|}}}}} | expired | active }}

Notice the #if that only displays an image if the image parameter is supplied, and the #ifexpr that toggles a status based on a timestamp. This pattern is common in project‑tracking pages where you want a visual cue for “still open” versus “closed”.

Semantic MediaWiki (SMW) hooks

If your wiki runs SMW, you can sprinkle #set statements right inside a template, turning it into a data entry point:

{{#set:
|Category=Project
|Start date={{{start|}}}
|End date={{{end|}}}
|Status={{#ifexpr: {{#time:U}} < {{#time:U|{{{end|}}}}} | Ongoing | Completed }}
}}

Now every page that includes {{ProjectCard|start=2023‑01‑01|end=2023‑12‑31}} automatically feeds the triple store. The result? You can query “all ongoing projects” without ever touching a spreadsheet.

Reusable Structures – The Real Power Play

Think of templates as Lego bricks. One brick can be a button, another a citation box, and when you click them together you get a fully‑fledged article layout. The key to mastery is designing each brick so it can be repurposed without a hitch.

Parameter design tips

Give parameters sensible defaults. If you forget to pass date, a fallback like {{{date|{{CURRENTDAY}} {{CURRENTMONTHNAME}} {{CURRENTYEAR}}}}} keeps the output tidy.
Prefer named over positional parameters. Readers can see title=… instead of guessing which number slot does what.
Document inside the template. A short comment at the top—e.g., —saves future maintainers a headache.

Layering templates

Sometimes a single template gets too crowded. Split concerns: a Template:CardHeader for the title bar, a Template:CardBody for the main text, and a Template:CardFooter for metadata. Then wrap them in a master Template:Card that glues everything together:

{{#if:{{{title|}}}|{{CardHeader|title={{{title}}}}}|}}
{{CardBody|content={{{content}}}}}
{{#if:{{{author|}}}|{{CardFooter|author={{{author}}}}}|}}

Later you can replace just the header style and all cards instantly get a facelift. That’s the beauty of modularity.

Common Pitfalls (and how to dodge them)

Templates are powerful, but they’re also a common source of subtle bugs. Here are a few things I’ve tripped over more times than I’d like to admit:

Infinite recursion. Accidentally calling your own template inside itself creates a loop that crashes the parser. A quick check: search for {{{ patterns that match the template name.
Parameter name collisions. If two nested templates both expect title, the inner one will silently override the outer value. Prefixing helps—e.g., card_title vs modal_title.
Whitespace quirks. MediaWiki trims leading spaces, but not always inside tags. A stray space can break a table layout. I’ve learned to run a quick “view source” after every edit.

Testing and Maintenance

Even seasoned editors treat templates like a tiny app: they need unit tests, versioning, and occasionally a refactor. The MediaWiki community recommends a sandbox page for each template where you dump a set of typical use‑cases. For example, a Template:Infobox sandbox might contain:

{{Infobox
|title=Sample article
|image=Example.png
|date=2025‑04‑01
|status=active
}}

Load the sandbox, verify the output, and commit. If the wiki runs VisualEditor, you can even preview changes in real time, which feels like a tiny IDE for wikis.

Putting It All Together – A Mini‑Project

Suppose you run an internal knowledge base for a software team. You want every “Feature” page to have a uniform header, a status badge, a list of owners, and a changelog table. Here’s a stripped‑down blueprint:


'''{{{name|Unnamed Feature}}}''' – {{#ifexpr: {{{status|}}}=done | ✅ Done | 🕒 In progress }}


* '''Owner:''' {{{owner|TBD}}}
* '''Created:''' {{{created|{{CURRENTDATE}}}}}


{| class="wikitable"
! Date !! Change !! By
{{#foreach: {{#arraymap:{{{log|}}}|,|x|{{!}} {{{x}}} {{!}}}}}}
|}


{{FeatureHeader|name={{{name}}}|status={{{status}}}}}
{{FeatureMeta|owner={{{owner}}}|created={{{created}}}}}
{{FeatureLog|log={{{log}}}}}

Drop {{FeatureCard|name=Auto‑deploy|status=done|owner=Alice|log=2025‑01‑01,Initial rollout, Alice;2025‑02‑15,Hotfix, Bob}} on a page, and you instantly get a polished feature overview. Adding a new column to the log table? Change FeatureLog once, and every card reflects it.

Final Thoughts

Mastering MediaWiki templates isn’t about memorizing every parser function; it’s about adopting a mindset of reuse, modularity, and a dash of foresight. When you treat each template as a small, self‑contained component, the wiki evolves from a chaotic collection of pages into a living, maintainable knowledge ecosystem. Sure, you’ll hit a few snags—parameter clashes, stray spaces, the occasional recursion nightmare—but those are just the growing‑pain signs that you’re pushing the platform toward true efficiency.

So the next time you find yourself copying the same table layout for the third time this week, pause. A few minutes of template craftsmanship now can spare you hours of copy‑paste later. And if you ever feel lost, the official Help:Templates page is a solid compass—just remember to keep your own compass calibrated with the quirks you discover along the way.