Module:Unsubst/doc
This is the documentation page for Module:Unsubst
 | This Lua module is used on 2,200,000+ pages. To avoid large-scale disruption and unnecessary server load, any changes to it should first be tested in its /sandbox or /testcases subpages. The tested changes can then be added to this page in a single edit. Please consider discussing any changes on the talk page before implementing them. |
 | This module is subject to page protection. It is a highly visible module in use by a very large number of pages, or is substituted very frequently. Because vandalism or mistakes would affect many pages, and even trivial editing might cause substantial load on the servers, it is protected from editing. |
Helper module to facilitate a substituted template transform into a template transclusion.
Maintenance templates, such as {{Citation needed}} or {{Refimprove}}, should never be substituted. A trick to avoid that is to make a template substitute to its transcluded form.
Infoboxes should use Module:Unsubst-infobox, as should any other templates with parameters listed in block format by default.
Usage
To turn a template into a self-substituting template, wrap the existing template code with:
{{ {{{|safesubst:}}}#invoke:Unsubst||$B=
[ ... existing template code ... ]
}}
The wikitext to display when not substed must be given as "$B". All other parameters passed to the #invoke will be copied to the generated template invocation as default values. If the value of any of these default parameters is "__DATE__", that value in the generated template invocation will be the current month and year.
Some templates have a <noinclude> but no matching </noinclude> at the end of the template. In such cases the missing </noinclude> must be added before the ending }}.
Advanced
{{ {{{|safesubst:}}}#invoke:Unsubst||$params=[ parameters ]|$aliases=[ aliases ]|$flags=[ flags ]|$B=
[ ... existing template code ... ]
}}
Due to Lua limitations, parameters are normally ordered randomly when the template is substituted. |$params= can be used in #invoke:Unsubst to list template parameters in order, comma-separated (e.g. egg,bacon,sausage,cheese,spam). Numbered parameters should be before others in the list. Any remaining parameters are tacked onto the end of the generated invocation.
Parameter aliases can be listed in |$aliases= (and shouldn't be listed in |$params=), and will be replaced automatically. Each alias and its replacement should be formatted as alias>replacement, and each of those pairs should be comma-separated (e.g. œuf>egg,melt>cheese). Note that this parameter can function with or without |$params=.
Parameter |$flags= can be used to modify other facets of the module's behaviour; entries are comma-separated. Valid flags are override (allows parameters in the #invoke: to take precedence over parameters in the original template invocation); keep-whitespace (prevents whitespace from being trimmed from unnamed parameters); and remove-empty (removes empty parameters).
These parameters can be manipulated using parser functions to provide more complicated options (note that in the parameters any parser function, or template or module invocation, should also have {{{|safesubst:}}}).
Example
Consider a template Template:Example containing the following code:
{{ {{{|safesubst:}}}#invoke:Unsubst||foo=bar |date=__DATE__ |$B=
[ ... Template code goes here ... ]
}}
| Original | Result |
|---|---|
| {{subst:example}} | {{Example|foo=bar|date=November 2024}} |
| {{subst:example|foo=X}} | {{Example|foo=X|date=November 2024}} |
| {{subst:example|baz=X}} | {{Example|foo=bar|baz=X|date=November 2024}} |
| {{subst:example|date=January 2001}} | {{Example|foo=bar|date=January 2001}} |
