Module:Category handler/doc

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.

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  field. For example: 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.

(excluding  and  )
 * List of possible namespace parameters

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

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:

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 " " to prevent that template from categorizing. (See section nocat below.) Like this:

My new module
Hey guys, have you seen my new module?

Nice, isn't it? --~

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

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:

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 " " 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:

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:

If " " then this template will not categorize on subpages. For the rare occasion you only want to categorize on subpages, then use " ". 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 Template messages.

If you want a template to categorize on a blacklisted page, then feed " " 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 " " 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  near the top of the module code.

The "nocat" parameter
This module understands the nocat parameter:


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

Modules and templates that use category handler should forward nocat, so they too understand nocat. The code " " 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 " " then this template does not categorize.
 * If categories is empty or undefined then this template categorizes as usual.
 * If " " this template categorizes even when on blacklisted pages.
 * The categories parameter also accepts aliases for  and   as defined by Module:Yesno, e.g. "yes", "y", "true", and 1 for , and "no", "n", "false", and 0 for.

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 " " (empty but defined), or " ", 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 " ", then this template categorizes as usual.
 * If " " 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:

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.

That text will not show on blacklisted pages, so don't use this method to show any important information. Feeding " " 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:

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:



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:

Parameters
List of all parameters:


 * First positional parameter - for default settings
 * subpage = 'no' / 'only'
 * 1, 2, 3 ...
 * all = ' ' / 'Text'
 * main = 1, 2, 3 ... / ' ' / 'Text'
 * other = 1, 2, 3 ... / ' ' / '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'
 * 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  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.