Module:Unsubst

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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.

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 "$B". A parameter "$N" may also be seen in some templates; this was required in an older version of the module, but is no longer necessary and may be removed.

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 }}.

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=June 2024}}
{{subst:example|foo=X}}	{{Example|foo=X|date=June 2024}}
{{subst:example|baz=X}}	{{Example|foo=bar|baz=X|date=June 2024}}
{{subst:example|date=January 2001}}	{{Example|foo=bar|date=January 2001}}

local p = {}

local specialParams = {
	['$N'] = 'template name', -- Deprecated, but keeping until it is removed from transcluding templates
	['$B'] = 'template content',
}

p[''] = function ( frame )
	if not frame:getParent() then
		error( '{{#invoke:Unsubst|}} makes no sense without a parent frame' )
	end
	if not frame.args['$B'] then
		error( '{{#invoke:Unsubst|}} requires parameter $B (template content)' )
	end
	
	if mw.isSubsting() then
		---- substing
		-- Combine passed args with passed defaults
		local args = {}
		for k, v in pairs( frame.args ) do
			if not specialParams[k] then
				if v == '__DATE__' then
					v = mw.getContentLanguage():formatDate( 'F Y' )
				end
				args[k] = v
			end
		end
		for k, v in pairs( frame:getParent().args ) do
			args[k] = v
		end

		-- Build an equivalent template invocation
		-- First, find the title to use
		local titleobj = mw.title.new(frame:getParent():getTitle())
		local title
		if titleobj.namespace == 10 then -- NS_TEMPLATE
			title = titleobj.text
		elseif titleobj.namespace == 0 then -- NS_MAIN
			title = ':' .. titleobj.text
		else
			title = titleobj.prefixedText
		end

		-- Build the invocation body with numbered args first, then named
		local ret = '{{' .. title
		for k, v in ipairs( args ) do
			if string.find( v, '=', 1, true ) then
				-- likely something like 1=foo=bar, we need to do it as a named arg
				break
			end
			ret = ret .. '|' .. v
			args[k] = nil
		end
		for k, v in pairs( args ) do
			ret = ret .. '|' .. k .. '=' .. v
		end
		
		return ret .. '}}'
	else
		---- Not substing
		-- Just return the "body"
		return frame.args['$B'] .. (frame.args['$N'] and frame:getParent():getTitle() == mw.title.getCurrentTitle().prefixedText and '[[Category:Calls to Module:Unsubst that use $N]]' or '')
	end
end

return p