Template Inclusion and Transclusion Guide

Purpose

This page explains how MediaWiki controls what parts of a template are:

visible on the template page itself
visible when the template is used inside other pages (transcluded)

Understanding this mechanism is essential when building:

Cargo storage templates
Page Forms templates
system templates

Incorrect usage can cause:

wrong Cargo rows
unwanted text on pages
confusing behaviour

Core concept: Transclusion

What is transclusion?

When a page contains:

 Template:DigitalAsset

MediaWiki does NOT copy text.

Instead it:

loads Template:DigitalAsset
inserts its content dynamically
renders the result

This process is called transclusion.

So a template has two different contexts:

Context	Meaning
Template page itself	Template:DigitalAsset is opened directly
Transcluded page	The template is used inside another page

MediaWiki allows us to control what appears in each context.

The three inclusion modes

1. <noinclude>

Visible only on the template page itself. Hidden when the template is transcluded.

Use for:

documentation
instructions
comments for editors
maintenance notes

Example:

<noinclude>
This template stores DigitalAssets in Cargo.
Do not edit manually.
</noinclude>

Visible on:

Template:DigitalAsset

Not visible on:

DA:0001

2. <includeonly>

Visible only when transcluded. Hidden on the template page itself.

Use for:

Cargo storage
categories
logic
anything that should affect real data pages

Example:

<includeonly>
{{#cargo_store: ... }}
</includeonly>

Runs on:

DA:0001

Does NOT run on:

Template:DigitalAsset

3. No tags

Content without tags appears everywhere.

Visible:

on template page
on all pages using the template

Usually not desired for system templates.

Why this matters for Cargo (very important)

Cargo executes:

whenever the template is rendered.

If you do NOT use <includeonly>:

Opening:

Template:DigitalAsset

would also execute cargo_store.

Result:

unwanted database rows
template page stored as data
corrupted tables

Therefore:

All #cargo_store calls MUST be inside <includeonly>.

Standard professional structure for Cargo templates

Recommended pattern:

<noinclude>
Documentation for administrators and editors.
Explain fields and usage here.
</noinclude>

<includeonly>
{{#cargo_store:
 _table=DigitalAssets
 |id={{{id|}}}
 |file_id={{{file_id|}}}
}}
</includeonly>

Meaning:

documentation only visible to editors
storage only happens on real pages

Clean separation of concerns.

Mental model

Think of it like visibility scopes:

Tag	Visible to
noinclude	template editors only
includeonly	pages using the template only
none	everyone

Practical rules for this project

Cargo / data templates

Use:

includeonly for all functional logic
noinclude for documentation

Documentation templates

Usually no special tags needed

When unsure

Ask: "Should this appear on the template page or only on real pages?"

Common mistakes

Mistake	Result
cargo_store outside includeonly	unwanted rows created
documentation without noinclude	text appears on every page
mixing display and storage logic	hard to debug behaviour

Final advice

Templates are half content, half code.

Treat them like small programs:

keep logic minimal
keep behaviour explicit
separate documentation from execution

Clarity prevents subtle bugs.