Module:category Handler Sandbox

This is the module sandbox page for Module:Category handler ( diff).
See also the companion subpage for test cases ( run).

Module documentation[ view] [ ] [ history] [ purge]

This Lua module is used in system messages, and on approximately 4,650,000 pages, or roughly 8% of all pages.
Changes to it can cause immediate changes to the Wikipedia user interface.
To avoid major disruption and server load, any changes should be tested in the module's /sandbox or /testcases subpages, or in your own module sandbox. The tested changes can be added to this page in a single edit. Please discuss 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.

This module depends on the following other modules:

This module implements the {{ category handler}} template. The category handler template helps other templates to automate both categorization and category suppression. For information about using the category handler template in other templates, please see the template documentation. Keep reading for information about using the category handler module in other Lua modules, or for information on exporting this module to other wikis.

Use from other Lua modules

When not to use this module

For cases where a module only needs to categorise in one of the namespaces main (articles), file (images) or category, then using this module is overkill. Instead, you can simply get a title object using mw.title.getCurrentTitle and check the nsText field. For example:

local title = mw.title.getCurrentTitle()
if title.nsText == 'File' then
    -- do something
end

However, if your module needs to categorize in any other namespace, then we recommend you use this module, since it provides proper category suppression and makes it easy to select how to categorize in the different namespaces.

Namespaces

This module detects and groups all the different namespaces used on Wikipedia into several types. These types are used as parameter names in this module.

main = Main/article space, as in normal Wikipedia articles.

talk = Any talk space, such as page names that start with "Talk:", "User talk:", "File talk:" and so on.

user, wikipedia, file ... = The other namespaces except the talk pages. Namespace aliases are also accepted. See the table below for the full list.

other = Any namespaces that were not specified as a parameter to the template. See examples below.

List of possible namespace parameters

(excluding talk and other)

Namespace	Aliases
`main`
`user`
`wikipedia`	`project`, `wp`
`file`	`image`
`mediawiki`
`template`	`tm`
`help`
`category`
`portal`
`draft`
`timedtext`
`module`

Basic usage

This module takes two or more parameters. Here's an example using a hello world program:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local result = 'Hello world!'
    local category = categoryHandler{
        '[[Category:Somecat]]',
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end

return p

The above example uses the default settings for the category handler module. That means the example module will categorize on pages in the following namespaces:

main, file, help, category, portal and book

But it will not categorize in any other namespaces, e.g.:

talk, user, wikipedia, mediawiki, template ...

And it will not categorize on blacklisted pages. (See section blacklist below.)

The reason the category handler module does not categorize in some of the namespaces is that in those namespaces most modules and templates are just demonstrated or listed, not used. Thus most modules and templates should not categorize in those namespaces.

Any module or template that is meant for one or more of the namespaces where this module categorizes can use the basic syntax as shown above.

Advanced usage

This module takes one or more parameters named after the different page types as listed in section namespaces above. By using those parameters you can specify exactly in which namespaces your template should categorize. Like this:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local result = 'This is a module meant for articles and talk pages.'
    local category = categoryHandler{
        main = '[[Category:Somecat1]]', -- Categorize in main (article) space
        talk = '[[Category:Somecat2]]', -- Categorize in talk space
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end

return p

The above module will only categorize in main and talk space. But it will not categorize on /archive pages since they are blacklisted. (See section blacklist below.) And if you need to demonstrate (discuss) the module on a talkpage, then you can feed "nocat='true'" to prevent that template from categorizing. (See section nocat below.) Like this:

== My new module ==
Hey guys, have you seen my new module?
{{#invoke:mymodule|main|nocat=true}}
Nice, isn't it?
--~~~~

Sometimes we want to use the same category in several namespaces, then do like this:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local result = 'This is a module used in several namespaces.'
    local category = categoryHandler{
        main = '[[Category:Somecat1]]',
         1  = '[[Category:Somecat2]]', -- For help and user space
        help = 1,
        user = 1,
        talk = '', -- No categories on talk pages
        other = '[[Category:Somecat3]]', -- For all other namespaces
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end

return p

In the above example we use a numbered parameter to feed one of the categories, and then we tell this module to use that numbered parameter for both the help and user space.

The category handler module understands an unlimited number of numbered parameters.

The other parameter defines what should be used in the remaining namespaces that have not explicitly been fed data.

Note the empty but defined talk parameter. That stops this module from showing what has been fed to the other parameter, when in talk space.

The category handler module also has a parameter called all. It works like this:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local result = 'This is a module used in all namespaces.'
    local category = categoryHandler{
        all = '[[Category:Somecat1]]', -- Categorize in all namespaces
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end

return p

The above example will categorize in all namespaces, but not on blacklisted pages. If you want to demonstrate that module on a page, then use "nocat=true" to prevent the template from categorizing.

We suggest avoiding the all parameter, since modules and templates should preferably only categorize in the namespaces they need to.

The all parameter can also be combined with the rest of the parameters. Like this:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local result = 'This is a module used in all namespaces.'
    local category = categoryHandler{
        all = '[[Category:Somecat1]]', -- Categorize in all namespaces
        main = '[[Category:Somecat2]]', -- And add this in main space
        other = '[[Category:Somecat3]]', -- And add this in all other namespaces
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end

return p

If the above module is placed on an article, then it will add the categories "Somecat1" and "Somecat2". But on all other types of pages it will instead add "Somecat1" and "Somecat3". As the example shows, the all parameter works independently of the rest of the parameters.

Subpages

The category handler module understands the subpage parameter. Like this:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local result = 'This is a module used in all namespaces.'
    local category = categoryHandler{
        subpage = 'no' -- Don't categorize on subpages
        wikipedia = '[[Category:Somecat]]',
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end

return p

If "subpage='no'" then this template will not categorize on subpages. For the rare occasion you only want to categorize on subpages, then use "subpage='only'". If subpage is empty or undefined then this template categorizes both on basepages and on subpages.

Blacklist

This module has a blacklist of the pages and page types where templates should not auto-categorize. Thus modules that use this meta-template will for instance not categorize on /archive pages and on the subpages of Wikipedia:Template messages.

If you want a template to categorize on a blacklisted page, then feed "nocat = false" to the module when you place it on the page, thus skipping the blacklist check. Note that this module only categorizes if it has data for the namespace. For instance, if the basic syntax is used (see basic usage above), then even if you set "nocat = false" the template will not categorize on a talk page, since it has no data for talk pages. But it has data for help space, so on a blacklisted help page it will categorize.

The blacklist is located in the configuration table cfg.blacklist near the top of the module code.

The "nocat" parameter

This module understands the nocat parameter:

If "nocat = true" then this template does not categorize.
If nocat is nil then this template categorizes as usual.
If "nocat = false" this template categorizes even when on blacklisted pages. (See section blacklist above.)
The nocat parameter also accepts aliases for true and false as defined by Module:Yesno, e.g. "yes", "y", "true", and 1 for true, and "no", "n", "false", and 0 for false.

Modules and templates that use {{category handler}} should forward nocat, so they too understand nocat. The code "nocat = frame.args.nocat" shown in the examples on this page does that.

The "categories" parameter

For backwards compatibility this module also understands the categories parameter. It works the same as nocat. Like this:

If "categories = false" then this template does not categorize.
If categories is empty or undefined then this template categorizes as usual.
If "categories = true" this template categorizes even when on blacklisted pages.
The categories parameter also accepts aliases for true and false as defined by Module:Yesno, e.g. "yes", "y", "true", and 1 for true, and "no", "n", "false", and 0 for false.

The "category2" parameter

For backwards compatibility this template kind of supports the old "category =" parameter. But the parameter name "category" is already used in this module to feed category data for when in category space. So instead this template uses category2 for the usage similar to nocat. Like this:

If "category2 = "" (empty but defined), or "category2 = 'no'", or if category2 is fed any other data (except as described in the next two points), then this template does not categorize.
If category2 is undefined or if "category2 = '¬'", then this template categorizes as usual.
If "category2 = 'yes'" this template categorizes even when on blacklisted pages.

Categories and text

Besides from categories, you can feed anything else to this module, for instance some text. Like this:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local result = 'This is a module used on talk pages.'
    local category = categoryHandler{
        talk = '[[Category:Somecat]]',
        other = '<p class="error">This module should only be used on talk pages.</p>',
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end

return p

When the module code above is used on anything other than a talk page, it will look like this:

This is a module used on talk pages.

This module should only be used on talk pages.

That text will not show on blacklisted pages, so don't use this method to show any important information. Feeding "nocat = 'true'" to the template hides the text, just as it suppresses any categories.

The "page" parameter

For testing and demonstration purposes this module can take a parameter named page. Like this:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local category = categoryHandler{
        main = 'Category:Some cat',
        talk = 'Category:Talk cat',
        nocat = frame.args.nocat, -- So "nocat=true/false" works
        page = 'User talk:Example'
    }
    return category
end

return p

In the above code we on purpose left out the brackets around the category names so we see the output on the page. No matter on what kind of page the code above is used it will return this:

Category:Talk cat

The page parameter makes this module behave exactly as if on that page. Even the blacklist works. The pagename doesn't have to be an existing page.

If the page parameter is empty or undefined, the name of the current page determines the result.

You can make it so your module also understands the page parameter. That means you can test how your template will categorize on different pages, without having to actually edit those pages. Then do like this:

p = {}
local categoryHandler = require( 'Module:Category handler' ).main

function p.main( frame )
    local category = categoryHandler{
        main = 'Category:Some cat',
        talk = 'Category:Talk cat',
        nocat = frame.args.nocat, -- So "nocat=true/false" works
        page = frame.args.page -- For testing
    }
    return category
end

return p

Parameters

List of all parameters:

First positional parameter - for default settings
subpage = 'no' / 'only'
1, 2, 3 ...
all = '[[Category:Somecat]]' / 'Text'
main = 1, 2, 3 ... / '[[Category:Somecat]]' / 'Text'
...
other = 1, 2, 3 ... / '[[Category:Somecat]]' / 'Text'
nocat = frame.args.nocat / true / false / 'yes' / 'no' / 'y' / 'n' / 'true' / 'false' / 1 / 0
categories = frame.args.categories / false / true / 'no' / 'yes' / 'n' / 'y' / 'false' / 'true' / 0 / 1
category2 = frame.args.category or '¬' / 'no' / 'not defined' / '¬' / 'yes'
page = frame.args.page / 'User:Example'

Note that empty values to the "main" ... "other" parameters have special meaning (see examples above). The "all" parameter doesn't understand numbered parameters, since there should never be a need for that.

Exporting to other wikis

This module can be exported to other wikis by changing the configuration values in the cfg table. All the variable values are configurable, so after the configuration values have been set there should be no need to alter the main module code. Details of each configuration value are included in the module code comments. In addition, this module requires Module:Namespace detect to be available on the local wiki.


--------------------------------------------------------------------------------

--                                                                            --

--                              CATEGORY HANDLER                              --

--                                                                            --

--      This module implements the {{category handler}} template in Lua,      --

--      with a few improvements: all namespaces and all namespace aliases     --

--      are supported, and namespace names are detected automatically for     --

--      the local wiki. This module requires [[Module:Namespace detect]]      --

--      and [[Module:Yesno]] to be available on the local wiki. It can be     --

--      configured for different wikis by altering the values in              --

--      [[Module:Category handler/config]], and pages can be blacklisted      --

--      from categorisation by using [[Module:Category handler/blacklist]].   --

--                                                                            --

--------------------------------------------------------------------------------



-- Load required modules

local yesno = require('Module:Yesno')



-- Lazily load things we don't always need

local mShared, mappings



local p = {}



--------------------------------------------------------------------------------

-- Helper functions

--------------------------------------------------------------------------------



local function trimWhitespace(s, removeBlanks)

	if type(s) ~= 'string' then

		return s

	end

	s = s:match('^%s*(.-)%s*$')

	if removeBlanks then

		if s ~= '' then

			return s

		else

			return nil

		end

	else

		return s

	end

end



--------------------------------------------------------------------------------

-- CategoryHandler class

--------------------------------------------------------------------------------



local CategoryHandler = {}

CategoryHandler.__index = CategoryHandler



function CategoryHandler.new(data, args)

	local obj = setmetatable({ _data = data, _args = args }, CategoryHandler)

	

	-- Set the title object

	do

		local pagename = obj:parameter('demopage')

		local success, titleObj

		if pagename then

			success, titleObj = pcall(mw.title.new, pagename)

		end

		if success and titleObj then

			obj.title = titleObj

			if titleObj == mw.title.getCurrentTitle() then

				obj._usesCurrentTitle = true

			end

		else

			obj.title = mw.title.getCurrentTitle()

			obj._usesCurrentTitle = true

		end

	end



	-- Set suppression parameter values

	for _, key in ipairs{'nocat', 'categories'} do

		local value = obj:parameter(key)

		value = trimWhitespace(value, true)

		obj'_' .. key = yesno(value)

	end

	do

		local subpage = obj:parameter('subpage')

		local category2 = obj:parameter('category2')

		if type(subpage) == 'string' then

			subpage = mw.ustring.lower(subpage)

		end

		if type(category2) == 'string' then

			subpage = mw.ustring.lower(category2)

		end

		obj._subpage = trimWhitespace(subpage, true)

		obj._category2 = trimWhitespace(category2) -- don't remove blank values

	end

	return obj

end



function CategoryHandler:parameter(key)

	local parameterNames = self._data.parameterskey

	local pntype = type(parameterNames)

	if pntype == 'string' or pntype == 'number' then

		return self._argsparameterNames

	elseif pntype == 'table' then

		for _, name in ipairs(parameterNames) do

			local value = self._argsname

			if value ~= nil then

				return value

			end

		end

		return nil

	else

		error(string.format(

			'invalid config key "%s"',

			tostring(key)

		), 2)

	end

end



function CategoryHandler:isSuppressedByArguments()

	return

		-- See if a category suppression argument has been set.

		self._nocat == true

		or self._categories == false

		or (

			self._category2

			and self._category2 ~= self._data.category2Yes

			and self._category2 ~= self._data.category2Negative

		)



		-- Check whether we are on a subpage, and see if categories are

		-- suppressed based on our subpage status.

		or self._subpage == self._data.subpageNo and self.title.isSubpage

		or self._subpage == self._data.subpageOnly and not self.title.isSubpage

end



function CategoryHandler:shouldSkipBlacklistCheck()

	-- Check whether the category suppression arguments indicate we

	-- should skip the blacklist check.

	return self._nocat == false

		or self._categories == true

		or self._category2 == self._data.category2Yes

end



function CategoryHandler:matchesBlacklist()

	if self._usesCurrentTitle then

		return self._data.currentTitleMatchesBlacklist

	else

		mShared = mShared or require('Module:Category handler/shared')

		return mShared.matchesBlacklist(

			self.title.prefixedText,

			mw.loadData('Module:Category handler/blacklist')

		)

	end

end



function CategoryHandler:isSuppressed()

	-- Find if categories are suppressed by either the arguments or by

	-- matching the blacklist.

	return self:isSuppressedByArguments()

		or not self:shouldSkipBlacklistCheck() and self:matchesBlacklist()

end



function CategoryHandler:getNamespaceParameters()

	if self._usesCurrentTitle then

		return self._data.currentTitleNamespaceParameters

	else

		if not mappings then

			mShared = mShared or require('Module:Category handler/shared')

			mappings = mShared.getParamMappings(true) -- gets mappings with mw.loadData

		end

		return mShared.getNamespaceParameters(

			self.title,

			mappings

		)

	end

end



function CategoryHandler:namespaceParametersExist()

	-- Find whether any namespace parameters have been specified.

	-- We use the order "all" --> namespace params --> "other" as this is what

	-- the old template did.

	if self:parameter('all') then

		return true

	end

	if not mappings then

		mShared = mShared or require('Module:Category handler/shared')

		mappings = mShared.getParamMappings(true) -- gets mappings with mw.loadData

	end

	for ns, params in pairs(mappings) do

		for i, param in ipairs(params) do

			if self._argsparam then

				return true

			end

		end

	end

	if self:parameter('other') then

		return true

	end

	return false

end



function CategoryHandler:getCategories()

	local params = self:getNamespaceParameters()

	local nsCategory

	for i, param in ipairs(params) do

		local value = self._argsparam

		if value ~= nil then

			nsCategory = value

			break

		end

	end

	if nsCategory ~= nil or self:namespaceParametersExist() then

		-- Namespace parameters exist - advanced usage.

		if nsCategory == nil then

			nsCategory = self:parameter('other')

		end

		local ret = {self:parameter('all')}

		local numParam = tonumber(nsCategory)

		if numParam and numParam >= 1 and math.floor(numParam) == numParam then

			-- nsCategory is an integer

			ret#ret + 1 = self._argsnumParam

		else

			ret#ret + 1 = nsCategory

		end

		if #ret < 1 then

			return nil

		else

			return table.concat(ret)

		end

	elseif self._data.defaultNamespacesself.title.namespace then

		-- Namespace parameters don't exist, simple usage.

		return self._args1

	end

	return nil

end



--------------------------------------------------------------------------------

-- Exports

--------------------------------------------------------------------------------



local p = {}



function p._exportClasses()

	-- Used for testing purposes.

	return {

		CategoryHandler = CategoryHandler

	}

end



function p._main(args, data)

	data = data or mw.loadData('Module:Category handler/data')

	local handler = CategoryHandler.new(data, args)

	if handler:isSuppressed() then

		return nil

	end

	return handler:getCategories()

end



function p.main(frame, data)

	data = data or mw.loadData('Module:Category handler/data')

	local args = require('Module:Arguments').getArgs(frame, {

		wrappers = data.wrappers,

		valueFunc = function (k, v)

			v = trimWhitespace(v)

			if type(k) == 'number' then

				if v ~= '' then

					return v

				else

					return nil

				end

			else

				return v

			end

		end

	})

	return p._main(args, data)

end



return p