Module:Redirect

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This module contains functions to find the target of a redirect page.

Main

The main function accepts the name of a single page. It determines if the page is a redirect; if so it looks up the page, extracts the target, and returns the target name as text. Its usage is {{#invoke:redirect|main|redirect-page-name}}.

The template normally neither takes nor gives square brackets, so to show the result as a link use [[{{#invoke:redirect|main|redirect-page-name}}]]. An error is produced if the redirect does not exist, but for versatility no error is given if the file is not a redirect (returns the original text) or if the file name is blank (returns blank).

However, if the parameter bracket is given a nonblank value, brackets will be passed on if present.

Examples

• {{#invoke:redirect|main|WP:AFC}} → WP:AFC
• {{#invoke:redirect|main|[[WP:AFD]]|bracket=yes}} → WP:AFD
• {{#invoke:redirect|main|TechInfoDepot:Articles for deletion}} → TechInfoDepot:Articles for deletion

Note: WP:AFC and WP:AFD are both redirects, but TechInfoDepot:Articles for deletion is not.

LuaMain

If you want to use the main function from another Lua module, you may want to use the luaMain function. This provides the same functionality as the main function, but doesn't require that a frame object be available.

To use this, first load the module.

local mRedirect = require('Module:Redirect')

Then use the function with the following syntax:

mRedirect.luaMain(rname, bracket)

rname is the name of the redirect page, and if bracket is anything but false or nil, the module will produce a link rather than just a page name.

IsRedirect

The isRedirect function is used from wiki pages to find out if a given page is a redirect or not. If the page is a redirect, the function returns "yes", and if not the output is blank. Its usage is {{#invoke:redirect|isRedirect|redirect-page-name}}.

Examples

• {{#invoke:redirect|isRedirect|WP:AFC}} →
• {{#invoke:redirect|isRedirect|TechInfoDepot:Articles for deletion}} →

GetTarget

The getTarget function fetches the target page name of a redirect page, and is only usable from Lua. If the page specified is a redirect, then the target is returned; otherwise the function returns nil.

To use it, first load the module.

local mRedirect = require('Module:Redirect')

Then use the function with the following syntax:

mRedirect.getTarget(page)

page can be either the name of the redirect page as a string, or a mw.title object.

See also

• bugzilla:66974 - Provide a standard way to get the target of a redirect page
• mw:Extension:Scribunto/Lua reference manual#Title objects, the Scribunto interface for determining a page's redirect status
• Template:Submit an edit request, which uses this module

-- This module provides functions for getting the target of a redirect page.

local p = {}

-- Gets a mw.title object, using pcall to avoid generating script errors if we
-- are over the expensive function count limit (among other possible causes).
local function getTitle(...)
	local success, titleObj = pcall(mw.title.new, ...)
	if success then
		return titleObj
	else
		return nil
	end
end

-- Gets the name of a page that a redirect leads to, or nil if it isn't a
-- redirect.
function p.getTargetFromText(text)
	return string.match(
		text,
		"^%s*#[Rr][Ee][Dd][Ii][Rr][Ee][Cc][Tt]%s*:?%s*%[%[([^%[%]]-)%]%]"
	)
end

-- Gets the target of a redirect. If the page specified is not a redirect,
-- returns nil.
function p.getTarget(page)
	-- Get the title object. Both page names and title objects are allowed
	-- as input.
	local titleObj
	if type(page) == 'string' or type(page) == 'number' then
		titleObj = getTitle(page)
	elseif type(page) == 'table' and type(page.getContent) == 'function' then
		titleObj = page
	else
		error(string.format(
			"bad argument #1 to 'getTarget'"
				.. " (string, number, or title object expected, got %s)",
			type(page)
		), 2)
	end
	if not titleObj or not titleObj.isRedirect then
		return nil
	end
	
	-- Find the target by using string matching on the page content.
	local target = p.getTargetFromText(titleObj:getContent() or "")
	if target then
		local targetTitle = getTitle(target)
		if targetTitle then
			return targetTitle.prefixedText
		else
			return nil
		end
	else
		-- The page is a redirect, but matching failed. This indicates a bug in
		-- the redirect matching pattern, so throw an error.
		error(string.format(
			'could not parse redirect on page "%s"',
			titleObj.prefixedText
		))
	end
end

--[[
-- Given a single page name determines what page it redirects to and returns the
-- target page name, or the passed page name when not a redirect. The passed
-- page name can be given as plain text or as a page link.
-- 
-- Returns page name as plain text, or when the bracket parameter is given, as a
-- page link. Returns an error message when page does not exist or the redirect
-- target cannot be determined for some reason.
--]]
function p.luaMain(rname, bracket)
	if type(rname) ~= "string" or not rname:find("%S") then
		return nil
	end
	bracket = bracket and "[[%s]]" or "%s"
	rname = rname:match("%[%[(.+)%]%]") or rname
	local target = p.getTarget(rname)
	local ret = target or rname
	ret = getTitle(ret)
	if ret then
		ret = ret.prefixedText
		return bracket:format(ret)
	else
		return nil
	end
end

-- Provides access to the luaMain function from wikitext.
function p.main(frame)
	local args = require('Module:Arguments').getArgs(frame, {frameOnly = true})
	return p.luaMain(args[1], args.bracket) or ''
end

-- Returns "yes" if the specified page is a redirect, and the blank string
-- otherwise.
function p.isRedirect(frame)
	local args = require('Module:Arguments').getArgs(frame, {frameOnly = true})
	local titleObj = getTitle(args[1])
	if not titleObj then
		return ''
	end
	if titleObj.isRedirect then
		return 'yes'
	else
		return ''
	end
end

return p