Module:Format link

From The Kodiak Republic Wiki

This module, migrated from origins in Module:Hatnote, provides functionality for formatting links for display, including that powering the {{format link}} template.

It can pretty-format section links with the section symbol ("§") and appropriate whitespace, it automatically escapes category and file names with the colon trick, and includes functionality for italicizing the page or section name, and for detecting and categorizing results that produce red links.

Use from wikitext

The functions in this module cannot be used directly from #invoke, and must be used through templates instead. Please see Template:Format link for documentation on usage of that template.

Use from other Lua modules

To load this module from another Lua module, use the following code:

local mFormatLink = require('Module:Format link')

You can then use the functions as documented below.


    link = 'Link',
    display = 'Display',
    target = 'Target',
    italicizePage = true,
    italicizeSection = true,
    categorizeMissing = 'Pages using formatted red links'

Formats link as a wikilink. Categories and files are automatically escaped with the colon trick, and links to sections are automatically formatted as page § section, rather than the MediaWiki default of page#section.

Several options modify the output:

  • If the display value is present, then it will be used as a display value. Any manual piping (using the {{!}} magic word or similar) present in link will be overridden by the display value if present.
  • If the target value is present, then it will override link as a target, but the result will still be displayed using either the value from display, or the result of formatting link.
  • If italicizePage is true, then the page portion of the link is italicized if present.
  • If italicizeSection is true, then the section portion of the link is italicized if present.
  • If categorizeMissing is a non-empty string, then that value is used as a category name, and that category will be applied if the resulting target of the link (no matter whether through link or through target) doesn't exist.
mFormatLink._formatLink{link = 'Foo#Bar'} → [[:Foo#Bar|Foo § Bar]] → Foo § Bar
mFormatLink._formatLink{link = 'Baz', display = 'Qux'} → [[:Baz|Qux]] → Qux
mFormatLink._formatLink{link = 'Foo|Bar', display = 'Baz'} → [[:Foo|Baz]] → Baz
mFormatLink._formatLink{link = '#Foo', target = 'Example#Foo'} → [[:Example#Foo|§ Foo]] → § Foo
mFormatLink._formatLink{link = 'The Lord of the Rings#Plot', italicizePage = true} → [[:The Lord of the Rings#Plot|''The Lord of the Rings'' § Plot]] → The Lord of the Rings § Plot
mFormatLink._formatLink{link = 'Cybercrime Prevention Act of 2012#Disini v. Secretary of Justice', italicizeSection = true} → [[:Cybercrime Prevention Act of 2012#Disini v. Secretary of Justice|Cybercrime Prevention Act of 2012 § ''Disini v. Secretary of Justice'']] → Cybercrime Prevention Act of 2012 § Disini v. Secretary of Justice
mFormatLink._formatLink{link = 'Nonexistent page', categorizeMissing = 'Example'} → [[:Nonexistent page]][[Category:Example]] → Nonexistent page
mFormatLink._formatLink{link = 'Existing', categorizeMissing = 'Example'} → [[:Existing]] → Existing


mFormatLink.formatPages(options, pages)

This derived function is useful for lists that format many links. It formats an array of pages using the _formatLink function, and returns the result as an array. Options in the options table are applied, and use the same names as the options for _formatLink.

mFormatLink.formatPages({categorizeMissing = 'Example'}, {'Foo#Bar', 'Nonexistent page'}){'[[:Foo#Bar|Foo § Bar]]', '[[:Nonexistent page]][[Category:Example]]'}


If _formatLink is used and neither a link nor a target argument is provided, then the module will produce an error message instead of its usual output, as it cannot then produce valid output.

You can solve this error by providing appropriate parameters to _formatLink, or you may want to ensure that a more descriptive error is provided by a downstream template or module when it would otherwise call _formatLink with inadequate arguments.

-- Format link
-- Makes a wikilink from the given link and display values. Links are escaped
-- with colons if necessary, and links to sections are detected and displayed
-- with " § " as a separator rather than the standard MediaWiki "#". Used in
-- the {{format link}} template.
local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local checkTypeForNamedArg = libraryUtil.checkTypeForNamedArg
local mArguments -- lazily initialise [[Module:Arguments]]
local mError -- lazily initialise [[Module:Error]]
local yesno -- lazily initialise [[Module:Yesno]]

local p = {}

-- Helper functions

local function getArgs(frame)
	-- Fetches the arguments from the parent frame. Whitespace is trimmed and
	-- blanks are removed.
	mArguments = require('Module:Arguments')
	return mArguments.getArgs(frame, {parentOnly = true})

local function removeInitialColon(s)
	-- Removes the initial colon from a string, if present.
	return s:match('^:?(.*)')

local function maybeItalicize(s, shouldItalicize)
	-- Italicize s if s is a string and the shouldItalicize parameter is true.
	if s and shouldItalicize then
		return '<i>' .. s .. '</i>'
		return s

local function parseLink(link)
	-- Parse a link and return a table with the link's components.
	-- These components are:
	-- - link: the link, stripped of any initial colon (always present)
	-- - page: the page name (always present)
	-- - section: the page name (may be nil)
	-- - display: the display text, if manually entered after a pipe (may be nil)
	link = removeInitialColon(link)

	-- Find whether a faux display value has been added with the {{!}} magic
	-- word.
	local prePipe, display = link:match('^(.-)|(.*)$')
	link = prePipe or link

	-- Find the page, if it exists.
	-- For links like [[#Bar]], the page will be nil.
	local preHash, postHash = link:match('^(.-)#(.*)$')
	local page
	if not preHash then
		-- We have a link like [[Foo]].
		page = link
	elseif preHash ~= '' then
		-- We have a link like [[Foo#Bar]].
		page = preHash

	-- Find the section, if it exists.
	local section
	if postHash and postHash ~= '' then
		section = postHash
	return {
		link = link,
		page = page,
		section = section,
		display = display,

local function formatDisplay(parsed, options)
	-- Formats a display string based on a parsed link table (matching the
	-- output of parseLink) and an options table (matching the input options for
	-- _formatLink).
	local page = maybeItalicize(, options.italicizePage)
	local section = maybeItalicize(parsed.section, options.italicizeSection)
	if (not section) then
		return page
	elseif (not page) then
		return mw.ustring.format('§&nbsp;%s', section)
		return mw.ustring.format('%s §&nbsp;%s', page, section)

local function missingArgError(target)
	mError = require('Module:Error')
	return mError.error{message =
		'Error: no link or target specified! ([[' .. target .. '#Errors|help]])'

-- Main functions

function p.formatLink(frame)
	-- The formatLink export function, for use in templates.
	yesno = require('Module:Yesno')
	local args = getArgs(frame)
	local link = args[1] or
	local target = args[3] or
	if not (link or target) then
		return missingArgError('Template:Format link')

	return p._formatLink{
		link = link,
		display = args[2] or args.display,
		target = target,
		italicizePage = yesno(args.italicizepage),
		italicizeSection = yesno(args.italicizesection),
		categorizeMissing = args.categorizemissing

function p._formatLink(options)
	-- The formatLink export function, for use in modules.
	checkType('_formatLink', 1, options, 'table')
	local function check(key, expectedType) --for brevity
			'_formatLink', key, options[key], expectedType or 'string', true
	check('italicizePage', 'boolean')
	check('italicizeSection', 'boolean')

	-- Normalize link and target and check that at least one is present
	if == '' then = nil end
	if == '' then = nil end
	if not ( or then
		return missingArgError('Module:Format link')

	local parsed = parseLink(
	local display = options.display or parsed.display
	local catMissing = options.categorizeMissing
	local category = ''

	-- Find the display text
	if not display then display = formatDisplay(parsed, options) end

	-- Handle the target option if present
	if then
		local parsedTarget = parseLink( = =

	-- Test if page exists if a diagnostic category is specified
	if catMissing and (mw.ustring.len(catMissing) > 0) then
		local title = nil
		if then title = end
		if title and (not title.isExternal) then
			local success, exists = pcall(function() return title.exists end)
			if success and not exists then
				category = mw.ustring.format('[[Category:%s]]', catMissing)
	-- Format the result as a link
	if == display then
		return mw.ustring.format('[[:%s]]%s',, category)
		return mw.ustring.format('[[:%s|%s]]%s',, display, category)

-- Derived convenience functions

function p.formatPages(options, pages)
	-- Formats an array of pages using formatLink and the given options table,
	-- and returns it as an array. Nil values are not allowed.
	local ret = {}
	for i, page in ipairs(pages) do
		ret[i] = p._formatLink{
			link = page,
			categorizeMissing = options.categorizeMissing,
			italicizePage = options.italicizePage,
			italicizeSection = options.italicizeSection
	return ret

return p
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