Help:TemplateData

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TemplateData is an extension used to store information about a wikitext template and its parameters so that an editing interface can retrieve and display this information in its template editor, thus making it easier for users to add and edit templates on pages.

Since April 2019, TemplateData is part of the default user experience for all users on all Wikimedia wikis when they add a template, including unregistered users. Both the default source and visual editors incorporate it in some way. It is also used elsewhere by scripts, tools and gadgets. If you have your own wiki, you will need to install Extension:TemplateData .

Adding TemplateData to a template essentially consists of inserting a small block of JSON code (explained below) on the template's documentation page. Whilst this may sound complicated, it's rather simple. There are two main ways you can do this, either manually or by using the TemplateData editor, a graphical user interface located on the "Edit"/"Edit source" pages of templates on wikis with the TemplateData extension installed. The JSON contains a list of parameters with info about each parameter of the template as well as the template as a whole. These are outlined below.

Once a template has TemplateData, this information will show in the user interface when a user adds the template, sometimes in place of original info or sometimes as additional info. In some cases, it may change how the editor behaves when editing or inserting the template. This can make it much easier for users to identify what they need to do with a template when adding it.

History

TemplateData was originally developed in early 2013 with VisualEditor in mind, which was in MediaWiki testing stages at the time. VisualEditor is the main visual editing interface for Wikimedia wikis, and TemplateData allowed it to have a more useful interface when adding templates. It was officially supported by VisualEditor immediately. As VisualEditor was rolled out to the various major Wikimedia wikis as a default feature from 2013 through 2016, TemplateData became a part of them as well.

In December 2016, the VisualEditor interface was made available for editing source code as a beta feature. This was termed the 2017 wikitext editor. This brought the features of TemplateData to source editing for the first time.

In March 2018, Sam Wilson developed TemplateWizard , a GUI template editor extension for the default Wikimedia source editor, WikiEditor (otherwise known as the 2010 wikitext editor), designed to make the process of adding templates easier by using information from TemplateData. In April 2019, TemplateWizard was made a default part of the 2010 wikitext editor on all Wikimedia wikis. This meant that TemplateData was now a default part of both the visual editor and the source editor on Wikimedia wikis.

Adding or editing TemplateData

To add or edit TemplateData, first navigate to a template's page, located at "/Template:Templatename".

Prior checks

There are two things you should check before adding or editing TemplateData, in the following order:

  1. whether the template has a documentation subpage
  2. whether the template already has TemplateData and whether this is located on the template page or the documentation subpage.

Checking for the documentation subpage

The first thing to do is identify whether the template has a subpage for its documentation or not.

There are two main ways templates on most Wikimedia wikis store their usage notes and other data that shouldn't be included in the actual template itself, like categories the template should be contained in:

  • The vast majority use a documentation subpage. This is a page located at the template's name followed by "/doc". In this case, on the main template page after the template source code, there is only the text "{{Documentation}}" between <noinclude> tags. Here, the {{Documentation}} template transcludes all the /doc page's content onto the template page. This makes the template's source code look much cleaner.
  • A small minority keep the information on the template's main page, after its source code. In this case, it is contained after "{{Documentation|content=", which is between <noinclude> tags.

You can quickly identify whether a template has a /doc page by checking if the "Test Template Info-Icon - Version (2).svg Template documentation" (or similar) heading has links like "[view] [edit] [history] [purge]" after it. This may look slightly different on different wikis. Rarely, the main template page may still have documentation content even if you see these buttons and there is a /doc page. This will happen if a user has added a custom /doc page title between "{{Documentation|" and "|content=" then added content after "|content=".

A slightly more reliable way to check is by looking for the notice, "The above documentation is transcluded from Template:Templatename/doc" (or similar), in the box at the bottom of the page.

If a template doesn't have a documentation subpage

If a template doesn't have a documentation subpage, you have two options:

  • You can either create it and move its documentation (if it has any) there. After this, you can then add TemplateData to the documentation subpage. This is the preferred option.
  • Or, you can add or edit TemplateData on the main template page.

Creating the doc subpage and moving the documentation contents

On most Wikimedia wikis, you can only create a page if you are a registered user (and, at least on the English Wikipedia, have been for more than four days and have made at least ten edits).

To do this, click "Edit"/"Edit source" on the main template page, and look for the <noinclude> tags and their contents, usually at the bottom.

It should look something like this:

<noinclude>
{{Documentation|content=
== Usage ==

Information about usage.

== More example headings ==

More example contents

[[Category:Example category]]
[[Category:Example category 2]]
}}
</noinclude>

It might also have TemplateData already. This will look something like:

<noinclude>
{{Documentation|content=
...
<templatedata>
{
    "description": "",
    "params": {
        "1": {
            "label": "Example parameter",
            "description": "Example parameter description",
            "type": "string"
        }
    }
}
</templatedata>
</noinclude>

Select everything after "|content=" and before "</noinclude>", cut it, then delete "|content=", so you are just left with:

<noinclude>
{{Documentation}}
</noinclude>

Now, save the page.

Next, add "/doc" to the URL in the address bar after the template name, and press Enter. Then, click "Create source".

If your wiki has a {{Documentation subpage}} notice template, add it at the top. You may also want to add some other templates, like a {{Purge button}} or {{Purge}} link, if your wiki has it. See meta:Help:Template documentation for more info.

Beneath this, paste the contents of the clipboard.

Next, enclose the categories within <includeonly> tags. This is so that they don't have an effect on the doc subpage, only on the template's main page.

This will look like this:

<includeonly>
[[Category:Example category]]
[[Category:Example category 2]]
</includeonly>

Some wikis (including the English Wikipedia) have a {{Sandbox other}} template. Use this if the template can be expected to have a sandbox version, located at "Template:Templatename/sandbox". It will stop the categories from having an effect on the sandbox page.

This will look like this:

<includeonly>{{sandbox other||
[[Category:Example category]]
[[Category:Example category 2]]
}}</includeonly>

After this, click "Publish page".

You can now add or edit the TemplateData on the documentation subpage based on the guidance at #Methods.

Adding or editing TemplateData on the main template page

If you do not wish to or are unable to create the /doc page, you can add or edit TemplateData on the main template page. Follow the guidance at #Methods to do this.

If a template has a documentation subpage

If a template has a documentation subpage, you should now check whether it already has TemplateData and whether this is located on the template page or the documentation subpage.

Check both the template page and the /doc subpage for the presence of TemplateData documentation; this looks something like this:

Template parameters

ParameterDescriptionTypeStatus
Example parameter1

Example parameter description

Stringoptional

Alternatively, the TemplateData extension can perform this check for you. Simply click "Edit" or "Edit source" on either page.

If the template already has TemplateData on either page, you will see a yellow notice at the top of the page saying either:

"Please note: there is already a TemplateData block on the related page "Template:Templatename/doc"", or
"Please note: there is already a TemplateData block on the related page "Template:Templatename""

If the template has TemplateData on its documentation subpage

If the template has TemplateData on its documentation subpage, this is the page you should edit. You can do this by clicking the "[edit]" located after the heading "Test Template Info-Icon - Version (2).svg Template documentation" (or similar), or, if you are already on the /doc page, simply clicking "Edit" or "Edit source" at the top. Follow the guidance at #Methods to add or edit the TemplateData.

If the template has TemplateData on its main page

If the template has TemplateData on its main page, you once again have two options:

  • You can either move to its documentation subpage. This is the preferred option.
  • Or, you can edit it on the main template page.

Moving TemplateData to the documentation subpage

To do this, simply click "Edit"/"Edit source" on the main template page, and look for the <templatedata> tags, enclosed within <noinclude> tags. It should look something like this:

<noinclude>
{{Documentation}}
<templatedata>
{
    "description": "",
    "params": {
        "1": {
            "label": "Example parameter",
            "description": "Example parameter description",
            "type": "string"
        }
    }
}
</templatedata>
</noinclude>

Cut only the <templatedata> tags and their contents out of the code, then save the page.

Next, edit the documentation subpage by clicking the "[edit]" located after the heading "Test Template Info-Icon - Version (2).svg Template documentation" (or similar).

Type a heading, like "TemplateData", then beneath it paste the TemplateData.

You can now edit the TemplateData based on the guidance at #Methods.

Editing TemplateData on the main template page

If you do not wish to move the TemplateData to the /doc page, you can edit it on the main template page. See #Methods for how to edit TemplateData.

If the template does not yet have TemplateData but has a doc subpage

If the template does not yet have TemplateData, you should add it to the documentation subpage.

Do this by clicking the "[edit]" located after the heading "Test Template Info-Icon - Version (2).svg Template documentation" (or similar), or, if you are already on the /doc page, simply clicking "Edit" or "Edit source" at the top. Type a heading, like "TemplateData", then add it beneath this heading. The section #Methods explains how to add TemplateData.

Methods

TemplateData editor method

This is the simpler way to add or edit TemplateData, possible for inexperienced users.

The TemplateData editor is a graphical user interface for adding and editing TemplateData. It is part of the TemplateData extension. It is accessible by going to any template's page (or documentation subpage) and clicking "Edit" or "Edit source".

After clicking "Edit" or "Edit source", you will see a button above the editing area and page title that says "Manage TemplateData". Manage template documentation button for TemplateData 2014.png

Clicking this button will enter the TemplateData editor. If the page you are on already contains TemplateData, this will automatically show here. A screenshot of the TemplateData editing tool

Features in the above window:

  • The top item is "Language". This item allows you to enter text content in multiple different languages, which will show depending on the language setting of the user in Preferences. It will not show depending on the language wiki, as different wikis have entirely different databases of templates. If no language TemplateData exists yet, only the language of the wiki the user is on will be available, but the user can click "Add language" to add more inputs. The language code will show in brackets next to the parameters for which it can be applied to. These include descriptions and labels.
  • The next item is the template description. This is the description of the template as a whole and is shown in various places to the user in the template editors while adding a template. This parameter and its effects are outlined here.
  • The third item is the wikitext formatting of the template. This parameter determines how the wikitext should be laid out when the user clicks "Insert", the two main types being "inline" (on one line) and "block" (on new lines). This parameter and its effects are outlined here.
If the user chooses "Custom", they will be able to enter a set of wikitext under "Custom format string", according to rules outlined here, to create a custom layout for the template when the user clicks "Insert".
  • The fourth item is "Template parameters". This contains a list of parameters already defined in the TemplateData, if they exist. If there are parameters stated in the template's source code for which no TemplateData exists yet, you may see a button called "Add suggested parameters". These are extracted from the template's source code by looking for {{{parametername}}} or {{{parametername|}}}. Clicking "Add suggested parameters" will add these parameters under their names as defined in the source code. This will also show a green notice at the top: "2 new parameters were imported: names of parameters".
  • At the bottom is "Add parameter". This allows you to add a parameter manually with a custom name.

The next stage is clicking any one of the parameters in the list. This will allow you to edit that parameter's info.


Screenshot of the TemplateData editor, showing a second parameter being added

All of these features and their effects are outlined at #Within a parameter's name.

  • The TemplateData editor will not allow you to change a parameter to a blank "Name". If you were to write a parameter in TemplateData with a blank string as a name, this would not cause issues in the 2010 wikitext editor with TemplateWizard, but it would not show up at all in VisualEditor or the 2017 wikitext editor. This is the only mandatory field in the TemplateData editor.
  • Clicking "Remove parameter information" will delete the parameter and all its information from the TemplateData. You will not be able to retrieve or undo this in the TemplateData unless you click "X" afterwards. You can undo any changes made after clicking "Apply" by simply hitting Ctrl+Z.
  • Exiting the TemplateData editor after making changes shows a prompt asking if you're sure you want to discard your changes.

When you are finished, click "Apply". This will automatically insert the TemplateData at the bottom of the page before the </noinclude> tag; or, if it already exists, it will update it with the new information without changing its position at all. The TemplateData text will also be selected when you click "Apply".

The TemplateData editor creates a "paramOrder" parameter at the bottom of the TemplateData or updates it if it already exists. This contains the current TemplateData parameters in the order they were displayed in the TemplateData editor. You can change the paramOrder by dragging the parameters in different orders in the TemplateData editor using the three horizontal bars on the left. "paramOrder" and its effects are outlined here.

After this, click "Save" to save the revision of the page.

Manual method

The alternative is to add or edit TemplateData manually. You may need or wish to do this in some cases. TemplateData's structure is based around the JSON standard, but you do not need to learn JSON to learn how to place TemplateData. It follows a few very simple rules and takes only a few dozen possible predefined parameters and values, almost always in a "parameter": "value" format.

Adding TemplateData manually

Preconsiderations:

  • If you're adding TemplateData on a template's documentation subpage, you may add it anywhere on the page; check to see if your language's Wikipedia has a preferred location for it. For example, on the English Wikipedia, TemplateData is typically near the bottom of the documentation page; on the German Wikipedia, it is typically at the top.
  • If you're adding TemplateData on a template's main page (which is not preferred; see #Prior checks), you must make sure that it is within the <noinclude></noinclude> tags.

First, click "Edit" or "Edit source" on the respective page, then go to the position you are adding the TemplateData and write a heading like "TemplateData".

Many wikis (but not all) have a {{TemplateData header}} template, which adds a short notice about the TemplateData. If yours does, add this after the heading.

To start adding the TemplateData, type an opening and closing <templatedata> tag and a pair of curly brackets on new lines, with an empty line between them:

<templatedata>
{

}
</templatedata>

Next, add an indent on the empty line between the two curly brackets, and start adding parameters. Details for the parameters can be found at #TemplateData parameters. Most are optional, but some are highly recommended.

Parameters can be in any order, but the order that will best correlate with what shows in the TemplateData documentation and contribute to ease of use for editors is the following:

<templatedata>
{
    "description": "",
    "format": "",
    "params": {
        "parameter1": {
            "aliases": ["",""]
            "label": "",
            "description": "",
            "type": ""
        }
    },
    "paramOrder": [
    	""
    ]
}
</templatedata>

Also, make sure the parameters within, for example, the #Unexpected property object are kept within that object, or you will receive an "Unexpected property" error when you try to save.

Example

Here is some example TemplateData for a hypothetical cleanup template. The template would display a notice, and its source code would be programmed to place the page into a dated category based on the month and year entered. The notice could also contain a link to a talk page section, if specified. The TemplateData would look something like this:

<templatedata>
{
	"description": "Use this template to indicate that an article is in need of cleanup.",
	"format": "inline",
	"params": {
		"date": {
			"label": "Month and year",
			"description": "The month and year that the template was added",
			"type": "string",
			"autovalue": "{{SUBST:CURRENTMONTHNAME}} {{SUBST:CURRENTYEAR}}",
			"example": "January 2013",
			"suggested": true
		},
		"reason": {
			"aliases": ["1"],
			"label": "Reason",
			"description": "The reason the article is in need of cleanup",
			"type": "string"
		},
		"talk": {
			"aliases": ["talksection"],
			"label": "Talk page section",
			"description": "The section of the talk page containing relevant discussion",
			"type": "string"
		}
	},
	"paramOrder": [
		"date",
		"reason",
        "talk"
	]
}
</templatedata>

The corresponding TemplateData documentation would display as the following:

Use this template to indicate that an article is in need of cleanup.

Template parameters

This template prefers inline formatting of parameters.

ParameterDescriptionTypeStatus
Month and yeardate

The month and year that the template was added

Example
January 2013
Auto value
{{SUBST:CURRENTMONTHNAME}} {{SUBST:CURRENTYEAR}}
Stringsuggested
Reasonreason 1

The reason the article is in need of cleanup

Stringoptional
Talk page sectiontalk talksection

The section of the talk page containing relevant discussion

Stringoptional

TemplateData parameters

Each parameter for TemplateData is listed below with a description and example. They are also listed at Extension:TemplateData#Format.

  • This information is current as of February 2020 and may change if new parameters are added or the template editing interfaces get updates to support existing parameters or treat certain parameters differently.
  • Wiki markup will not work in descriptions or labels. They are strictly plain text strings.
  • New lines ("\n") in descriptions, labels, examples or defaults will not show in any of the main editors (TemplateWizard, VisualEditor or the 2017 wikitext editor), even though they show in the auto-generated TemplateData documentation. They are replaced by a null string in input forms and by a space elsewhere.
Parameter Description Example
description

The "description" parameter describes what the template does. It is optional but highly recommended.

Effects

On the template documentation page, the description will show in plain text below the "Template data for [template name]" subheading.

In all main editors (VisualEditor , the 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), the description shows in two main instances:

  • below the template name in each search suggestion when the user is searching for a template
  • below the template name in the template editor, while they are adding values to parameters in the template.

In the VisualEditor and 2017 wikitext editor, the description gets truncated to about 50 characters under each search suggestion, followed by a "...", but the whole description shows in the main template editor window. Both are shown in grey text.

In the 2010 wikitext editor with TemplateWizard, the whole description shows under each search suggestion, in grey text. In the main template editor window, descriptions longer than four lines (about 540 characters) are provided a separate scrollbar, and they are shown in black text.

If not specified

If the description parameter does not exist or is not specified, the text "No description." will be displayed in the TemplateData documentation below the "Template data for [template name]" subheading. Additionally:

  • in VisualEditor and the 2017 wikitext editor, it will behave the same as a template that does not have TemplateData; instead of a description, the following text will display:
"The "Template:Templatename" template doesn't yet have a description, but there might be some information on the template's page."
  • in the 2010 wikitext editor with TemplateWizard, the following text will display where the description would be (though not in search suggestions):
"No description exists for this template."
This is different to the two standard placeholder descriptions when TemplateData doesn't exist:
  • "Due to missing TemplateData, parameters for this template have been auto-generated. Please be aware that they may not be accurate."
  • "No parameters could be determined for this template due to absence of TemplateData documentation. You may insert the template without parameters."
"description": "A template for linking to a commons category",
format

The "format" parameter describes how the template's wikitext should be laid out. This can be set to the standard formats of "inline" and "block", or the user can input a set of wikitext symbols to create a custom format; these symbols and some examples are listed in the section #Custom formats.

This parameter is not required, but it is recommended. The default behaviour when this parameter does not exist is inline formatting, and no corresponding notice is displayed in the TemplateData documentation below the table heading.

Effects

Inline:

If the parameter is set to "inline", the template will display a corresponding notice about the preference in its TemplateData documentation, below the table heading, "Template parameters":

"[circles and pipes icon] This template prefers inline formatting of parameters."

When inserted, the template will lay its wikitext out on a single line with no white space between elements, like so:

{{Foo|bar=baz|qux=quux}}

Block:

If the parameter is set to "block", the template will display the following preference notice in its TemplateData documentation:

"[stacked blocks and pipes icon] This template prefers block formatting of parameters."

When inserted, the template will distribute its parameters each on a new line, with single spaces between each element, like so:

{{Foo
| bar = baz
| qux = quux
}}

Custom formatting:

Alternatively, if the parameter is set to a custom string of wikitext, as per the rules listed at #Custom formats, the template will display the following preference notice in its TemplateData documentation:

"[cogwheel icon] This template has custom formatting."

When inserted, the template will lay its wikitext out as per the given wikitext.

"format": "inline"
params

The "params" object contains the information for each parameter of the template. It is required, and its parameters can be viewed in the #Within params section.

It should contain the name of each parameter followed by a set of TemplateData sub-parameters listed in #Within a parameter's name.

If there are multiple parameters, separate each parameter object with a comma between each one, after the closing curly bracket (i.e. not after the last curly bracket).

"params": {
    "parameter1": {
        ...    // parameter info
    },      // comma here
    "parameter2": {
        ...    // parameter info
    },      // and here
    "parameter3": {
        ...    // parameter info
    }       // but not here
}
paramOrder

The "paramOrder" object is an optional object that can force the parameters of a template to show in a specific order when added in the template editor.

How to use

It is used by adding the parameter "paramOrder", followed by a colon, a space and an open square bracket, then typing the name of each of the template's parameters in speech marks in a desired order, separated by commas. Finally, end it with a closed square bracket. This creates an array.

The parameters do not have to be on new lines (they can be "paramOrder": ["param1","param2","param3"]), but placing them on new lines may aid in legibility.

It is recommended that you place "paramOrder" after "params", like how the TemplateData editor does, because it does not show in the TemplateData documentation but simply forces the order of the parameters. Someone might want to quickly look at the parameter details and edit them rather than scroll past the "paramOrder", especially if there are a lot of parameters. If you do choose to place it somewhere other than the end of the TemplateData, make sure it has a comma at the end.

Every parameter mentioned in the TemplateData must be included, otherwise a "Required property" error will show.

If not specified

If "paramOrder" does not exist or is not specified, the template's parameters will display in the order they are declared in the template's source code. If the source code contains objects inside objects, parameters in outer objects will come first, followed by inner objects.

With other parameters

In the 2010 wikitext editor with TemplateWizard, "required" parameters will always appear at the top, regardless of the order in "paramOrder", while "suggested" parameters will always appear second, above "optional" ones ("deprecated" parameters won't appear at all in this editor; see the description of "deprecated" for more info). "paramOrder" will only enforce its order within these categories (i.e., all "required" parameters will be in the order specified by "paramOrder", and all "suggested" parameters will be too, but all "suggested" parameters will appear below all "required" parameters).

In VisualEditor and the 2017 wikitext editor, "paramOrder" forces its order regardless of the status of each parameter.

"paramOrder": [
	"date",
	"reason",
	"talk"
]

Within params

Parameter Description Example
parameter name

The only first-level item of the params object is the name of a parameter of the template.

For example, in a template's source code, if you see {{{date}}}, this is a parameter, and this should be added under "params" with the name "date".

You may also see parameters named {{{1}}} or another number (whose TemplateData name should be, for example, "1"). These parameters behave in such a way that, when a user inserts a template, they can omit their name and the equals sign (i.e., |value| instead of |parametername=value|). Their number indicates which unnamed parameter they are when multiple unnamed parameters are used. For example, expect that in

{{example template|value1|value2}}

value1 is the value of parameter {{{1}}}, and value2 is the value of parameter {{{2}}}. Make sure to describe your TemplateData parameters accordingly. Note: a user can still force the use of {{{2}}} without {{{1}}} by simply inserting a parameter named "2" in the template editor or typing "|2=" in wikitext.

How to use

Each of these "parameter name" objects should contain all of the information about the parameter, in the form of more TemplateData parameters. These are listed in the following section, Within a parameter's name.

"1": {     // name of the parameter
    ...    // information about the parameter goes here
}

Within a parameter's name

Parameter Description Example
aliases

The "aliases" parameter is a optional item for when a template parameter has multiple names. You can check this by going into the template's source code and looking for:

{{{parameter1|{{{parameter2}}}}}}, or {{{parameter1|{{{parameter2|}}}}}}

This means that if the user inserts either of these parameters with a value, they will perform the same function. Literally, it translates to, "Value of parameter1. If parameter1 doesn't exist or have a value, value of parameter2." In the second case, it also means, "If parameter2 doesn't exist or have a value, no value."

To insert the "aliases" parameter, add the text "aliases" followed by a colon, a space and an open square bracket, then typing the name of each of the parameter's aliases in speech marks, separated by commas. Finally, end it with a closed square bracket. This creates an array.

"aliases": ["1", "talk", "talksection"],
inherits

"inherits" is an optional parameter for when a parameter should inherit all of the TemplateData of another parameter. This can then be overridden by any parameters specified for the inheriting parameter.

To use this parameter, type "inherits" : followed by another template parameter's name, such as "talk" or "1". You can then type another specific setting for the parameter underneath if you wish, like "label" : "A different label". The first parameter will inherit all of the second parameter's properties except this one.

    "params": {
        "topic1": {
            "label": "Topic",
            "description": "A topic mentioned on this disambiguation page",
            "type": "string"
        },
        "topic2": {
            "inherits": "topic1"
        },
        "topic3": {
            "inherits": "topic1",
            "label" : "A different label"
        }
    }
label

The "label" parameter is a human-readable title for the parameter that will be displayed within the template editor. It displays this in place of the parameter's raw name. This parameter is optional but highly recommended.

"label": "Month and year",
description

Here, "description" is a description of the parameter, not the template as a whole. This description is shown in a tooltip when the user hovers over the "i" symbol next to the parameter in the template editor. It is optional but highly recommended.

"description": "The month and year that the template was inserted",
type

See the #Type parameter section.

default

Occasionally, a template parameter is programmed to have a default value that is used unless you change it. The "default" item is an optional item intended to tell the user what this value is. The value does not have to match the actual default and has no functional effect. You can ignore this parameter if there's no default.

Effects

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), the "default" text will show as grey text in the input box of any open parameter when it is empty, in the format "Default: default text". Additionally, it will show in plain black text in the parameter description (when the user hovers over the "i" symbol). In VisualEditor and the 2017 wikitext editor, this will be below the parameter description, below "Field is required"/"Field is deprecated", if specified (the 2010 wikitext editor doesn't show this text), and above "example", if specified ("example" does not show in the parameter description in the 2010 wikitext editor). In the 2010 wikitext editor with TemplateWizard, the "default" text shows directly after the parameter description, on the same line, following a space. It shows in the same format as the other editors ("Default: default text").

With other parameters

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), if "default" is specified, the "example" value will not show in the input box.

"default": "Category:CommonsRoot",
autovalue

You can specify an "autovalue" for a parameter. When a user adds the template to a page, this value will automatically appear in the input box. For example, many cleanup templates are supposed to have the date added; if you set the autovalue for the template's date parameter to be {{subst:CURRENTMONTHNAME}} {{subst:CURRENTYEAR}}, the month and year that the template was added will be filled in automatically.

This parameter does not force the value to always be this value. The user can freely change the value that is automatically inputted into the parameter in the template editor.

With other parameters

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), "autovalue" overrides the visible effects of "url" in VisualEditor and the 2017 wikitext editor. See the description for "type" for more info.

"autovalue": "{{subst:CURRENTMONTHNAME}} {{subst:CURRENTYEAR}}"
example

The "example" value is an optional value intended to display an example input to show how the parameter is used.

Effects

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), it shows a grey text in the input box of any open parameter when it is empty, in the format "e.g. example text". Additionally, in VisualEditor and the 2017 wikitext editor, it shows the same text in black, non-italic font below the parameter description (and below the "default" text, if specified).

With other parameters

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), "example" will not show in the input box if "default" is specified.

"example": "January 2013",
required

We then have "required", which can be set to either true or false. If you don't specify, it will be assumed to be false.

This specifies whether filling out the parameter is mandatory for that template.

Effects

This status has several effects in VisualEditor and the 2017 wikitext editor :

  • it makes the parameter automatically show up when a user inserts a template;
  • it shows a grey asterisk next to the parameter label;
  • it shows a black asterisk within the input box, on the right;
  • it shows the grey, italic text "Field is required" below the parameter description;
  • it makes the input box glow red if the user clicks away without entering a value;
  • if a user attempts to insert the template without a value in the required parameter, it will show them a prompt, asking if they are sure. If they confirm, it will insert the parameter with a blank value. It will not stop them from inserting the template, though, and it does not result in a visible error by itself (though templates can be programmed to display an error when a required parameter is not filled in).

In the 2010 wikitext editor with TemplateWizard, like in the other editors, it causes the parameter to automatically show up when a user inserts a template, but in this editor the parameter cannot be removed. It also does not display "Field is required" in the parameter description; rather, it lists the parameter on the side under "Required parameters". Other than this, it generally behaves the same as in the other editors, except that the prompt says that the input doesn't "match the expected format".

With other parameters

In VisualEditor and the 2017 wikitext editor, the "deprecated" status does not override the functionality of this parameter, but in the 2010 wikitext editor with TemplateWizard it does. See the description of "deprecated" for more info.

"required": true
suggested

There is "suggested", which can be set to either true or false. If you don't specify, it will be assumed to be false.

This is a status for parameters that are not "required" but are recommended to be high value (but not mandatory) for template users.

Effects

In VisualEditor and the 2017 wikitext editor , it causes the parameter to automatically show up when a user inserts a template. If the parameter has an autovalue set, this will also automatically be in the parameter's input box. It has no other effect and doesn't show any additional text or warnings.

In the 2010 wikitext editor with TemplateWizard, it does not place the parameter in the template automatically but instead causes it to be listed on the side under "Suggested parameters". The user can then click a "+" next to the parameter to add it to the template.

With other parameters

The "required" status overrides the functionality of this status in all main editors (VisualEditor, the 2017 wikitext editor and the 2010 wikitext editor). It also overrides the displayed "suggested" status in TemplateData documentation (it will display "required" if both "required" and "suggested" are set to true).

"suggested": true
deprecated

Finally, there is "deprecated", which can be set to true, false, or a string describing what users should instead do. If you don't specify, it will be assumed to be false.

This is a status for parameters that should not be used any more but still exist for the time being. This could be because uses of the template are being moved from one set of parameters to another.

Effects

The effect of this parameter in VisualEditor and the 2017 wikitext editor is that a grey exclamation mark shows next to the parameter's label when it is inserted, and in the parameter's information tooltip, the grey, italic text "Field is deprecated" is shown below the parameter description. It does not affect the functionality or usability of the parameter or show any additional warnings.

Despite the fact that it can take a string, as of January 2020 none of the main editors (VisualEditor, the 2017 wikitext editor or the 2010 wikitext editor) display the contents of the string anywhere to users. Inputting a string has the same effect as true.

In the 2010 wikitext editor with TemplateWizard, setting this value as true does not allow the parameter to be added or seen.

With other parameters

If you set both this and "suggested" as true, the parameter status will show as "deprecated" in the TemplateData documentation, but in VisualEditor and the 2017 wikitext editor both functionalities will be retained; the parameter will automatically show up when a user inserts a template, but it will have the "deprecated" warnings around it.

If you set both this and "required" as true, the parameter status will show as "deprecated" in the TemplateData documentation, but in VisualEditor and the 2017 wikitext editor it will have the same functionality as only "required"; the parameter will automatically show up when a user inserts a template, and it will have the "required" warnings around it. This is the same for if you set "deprecated", "suggested" and "required" as true.

In the 2010 wikitext editor with TemplateWizard, "deprecated" overrides the parameters "required" and "suggested".

"deprecated": "Please use 'publicationDate' instead."

Note: if neither "required", "suggested" nor "deprecated" are set as true for a parameter, its status will show as "optional" in the TemplateData documentation.

Once you're done, hit "save". If you've made errors, it will not let you save (which is disruptive but means you can't break anything). Should you run into errors, explain on the feedback page what you were trying to do, and we will be happy to help.

Note that if you are abusing a hack template to dynamically generate TemplateData, it cannot be checked for errors before saving.

Note that each item of information is enclosed in quotation marks (except for true and false) and separated from the next bit by a comma (unless it's the last one).

Type parameter

The "type" parameter is meant to signal to a template editor the nature of a parameter's value. In some cases, template editors have been programmed to modify the user interface for a certain parameter according to this TemplateData value, such as to only allow the user to enter valid values that match the specified type. This parameter does not have any functional effect on the template parameter or its value; it merely controls how template editors see and treat the parameter in editing mode.

How to use

It is used by adding the "type" parameter, followed by a colon and a space, then adding any of the values listed in the table below in speech marks.

Example:

"type": "string",

Effects

As of February 2020, only 5 of the 13 type values have visible effects in VisualEditor and the 2017 wikitext editor, while 8 have visible effects in TemplateWizard.

The effects of certain values are likely to change as the template editors get updates to support them. One such effort for VisualEditor and the 2017 wikitext editor is tracked in the Phabricator task T55613. A similar effort to get TemplateWizard to support the boolean value is tracked in T200664.

The currently known effects are listed as follows.

Value Description
unknown The "unknown" value is the default type value if no type is set. It can also be set manually, by typing "type": "unknown".

Effects

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), "unknown" has no visible effects compared to a template without TemplateData.

number

The "number" value is intended for numerical values, including negative values and decimals.

Effects

  • In VisualEditor and the 2017 wikitext editor, "number" has no visible effect.
  • In the 2010 wikitext editor with TemplateWizard, "number" causes the input box to display a "+" and "-" button on either side, which can raise or lower a number value in the input box, and the user can only type numbers into the box. The buttons can also lower the number into negatives.

With other parameters

  • In the 2010 wikitext editor with TemplateWizard, "number" overrides the effects of "autovalue"; the value of "autovalue" will not be automatically placed in the input box if the parameter type is "number".
string

The "string" value is intended for any string of plain text.

Effects

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), "string" has no visible effect compared to "unknown".

line

The "line" value is intended for content that should be forced to stay on one line.

Effects

  • In VisualEditor and the 2017 wikitext editor, "line" prevents a parameter's input box from allowing new lines, which are usually possible in these editors.
  • In the 2010 wikitext editor with TemplateWizard, "line" has no visible effect (input boxes do not allow new lines by default in this editor).
boolean The "boolean" value is intended for a value that is either true, false or unknown. This is intended by the manual to be represented by a "1", "0" or blank value.

Effects

As of February 2020, none of the main Wikimedia editors (VisualEditor, 2017 wikitext editor or the 2010 wikitext editor with TemplateWizard) make use of this value. It has no visible effects.

date The "date" value is intended for a date in the YYYY-MM-DD (ISO 8601) format; for example, 2014-05-22. The TemplateData manual also designates it as being intended for ISO 8601 date–time combinations, such as 2014-05-22T16:01:12Z", but in practice no major editing interface as of February 2020 uses it in this fashion, and almost all major Wikimedia template parameters take dates and times separately.

Effects

  • In VisualEditor and the 2017 wikitext editor, "date" has no visible effect.
  • In the 2010 wikitext editor with TemplateWizard, "date" makes the parameter input box about a third shorter and adds a dropdown calendar, allowing the user to choose a date input. It also displays the grey example text in the input box "YYYY-MM-DD". If an input does not conform to this standard, the box glows red, however the editor will always output a date conforming to the standard (if numbers are entered) or nothing (if only text or nothing is entered).

With other parameters

  • In the 2010 wikitext editor with TemplateWizard, "date" overrides the effects of "autovalue"; the value of "autovalue" will not be automatically placed in the input box if the parameter type is "date".
url

The "url" value is intended for a URL, with Internet protocol (e.g., "https://" or "//") included.

Effects

  • In VisualEditor and the 2017 wikitext editor, "url" makes the input box display an external link icon (a square with arrow pointing out of it) in the left hand side of the box and makes the box glow red when the user clicks away without entering a URL value that includes a valid Internet protocol (e.g., "https://", "ftp://" or "//") followed by some text. This second effect is similar to that of the "required" setting, but it does not warn the user if they attempt to insert the template without a valid URL. It also occurs with any status setting (such as "suggested"" or "deprecated").
  • In the 2010 wikitext editor with TemplateWizard, "url" has no visible effect.

With other parameters

  • In VisualEditor and the 2017 wikitext editor, "autovalue" overrides the visible effects of "url": when both are set, the input box will not contain a URL icon nor glow red when the user clicks away without entering a valid URL.
wiki-page-name

The "wiki-page-name" value is intended for a page name on a wiki.

Effects

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), "wiki-page-name" makes the parameter input box show a suggestion dropdown menu containing a list of pages on the wiki, such as articles on Wikipedia, which can be selected. Namespaces can also be defined in the search. Additionally, in VisualEditor and the 2017 wikitext editor, it forces the input box content to stay on one line. It has no other visible effect and doesn't prevent a non-page from being inputted.

wiki-file-name

The "wiki-file-name" value is intended for a file name hosted either locally on a wiki or on Wikimedia Commons.

Effects

  • In VisualEditor and the 2017 wikitext editor, "wiki-file-name" has no visible effect.
  • In the 2010 wikitext editor with TemplateWizard, "wiki-file-name" makes the parameter input box show a suggestion dropdown menu containing a list of files hosted both locally and on Wikimedia Commons, which can be selected. The file names do not contain the "File:" namespace prefix. The dropdown menu also shows the thumbnail of the files. It has no other visible effect and doesn't prevent a non-file from being inputted.
wiki-template-name

The "wiki-template-name" value is intended for the name of a template.

Effects

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), "wiki-template-name" makes the parameter input box show a suggestion dropdown menu containing a list of templates, which can be selected. Additionally, in VisualEditor and the 2017 wikitext editor, it forces the input box content to stay on one line. It has no other visible effect and doesn't prevent a non-template from being inputted.

wiki-user-name

The "wiki-user-name" value is intended for a username on a wiki.

Effects

In all main editors (VisualEditor, 2017 wikitext editor and the 2010 wikitext editor with TemplateWizard), "wiki-user-name" makes the parameter input box show a suggestion dropdown menu containing a list of actual users' names, which can be selected. Additionally, in VisualEditor and the 2017 wikitext editor, it forces the input box content to stay on one line. It has no other visible effect and doesn't prevent a non-username from being inputted.

content

The "content" value is intended for wikitext of page content, for example, links, images or text formatting.

Effects

  • In VisualEditor and the 2017 wikitext editor, "content" has no visible effect.
  • In the 2010 wikitext editor with TemplateWizard, "content" makes the parameter input box one line taller and allows new lines, which regular input boxes in the 2010 wikitext editor do not.
unbalanced-wikitext

The "unbalanced-wikitext" value is intended for wikitext that cannot stand alone, i.e. it lacks an opening or closing tag or refers to other parts of wikitext.

Effects

  • In VisualEditor and the 2017 wikitext editor, "unbalanced-wikitext" has no visible effect.
  • In the 2010 wikitext editor with TemplateWizard, "unbalanced-wikitext" makes the parameter input box one line taller and allows new lines, which regular input boxes in the 2010 wikitext editor do not.

Custom formats

When editing the "format" value, you create custom formats by inputting a set of wikitext symbols using some predefined rules.

  • {{ - start of the template
  • _ - content (e.g., string, integer or parameter). This underscore serves to indicate the minimum length of a value in characters and can be repeated, like _______. If this length is not reached, it fills the remaining characters with spaces. This can be used to align all equals signs to a specific position after a parameter (if used with \n for new lines).
  • | - pipe (separates parameters)
  • = - equals sign (precedes the value of a parameter)
  • \n or pressing the enter key - new line (this will display as in the entry field)
  • - space (can be used with \n to indent new lines)
  • }} - end of the template

The wikitext should at least meet the minimum of {{_|_=_}}, otherwise there will be an invalid format string error.

Examples of formats you can use
Objective Format string Output
Inline formatting {{_|_=_}}
inline
{{Foo|bar=baz|qux=quux}}{{Bar}}
Block formatting {{_\n| _ = _\n}}
block
{{Foo
| bar = baz
| qux = quux
}}{{Bar
}}
No space before the parameter name,

each template on its own line

\n{{_\n|_ = _\n}}\n
{{Foo
|bar = baz
|qux = quux
}}
{{Bar
}}
Indent each parameter {{_\n |_ = _\n}}
{{Foo
 |bar = baz
 |qux = quux
}}{{Bar
}}
Align all parameter names to a given length {{_\n|_______________ = _\n}}\n
{{Foo
|bar             = baz
|qux             = quux
|veryverylongparameter = bat
}}
{{Bar
}}
Pipe characters at the end of the previous line {{_|\n _______________ = _}}
{{Foo|
  bar             = baz|
  qux             = quux}}{{Bar}}
Inline style with more spaces, must be at start of line \n{{_ | _ = _}}
{{Foo | bar = baz | qux = quux}}
{{Bar }}
Template at the start of a line, indent-aligned parameters, pipe beforehand \n{{_ |\n _______________ = _}}
{{Foo |
  bar             = baz |
  qux             = quux}}
{{Bar}}

Blank boilerplate

You can copy the blank boilerplate below to add new TemplateData to a template. Only the most common tags are included.

<templatedata>
{
    "description": "",
    "params": {
        "1": {
            "label": "",
            "description": "",
            "type": ""
        },
        "2": {
            "label": "",
            "description": "",
            "type": ""
        }
    }
}
</templatedata>

Errors

Syntax error in JSON / Bad JSON format

This error occurs if you attempt to save TemplateData that has certain types of invalid JSON code, such as duplicate keys (parameters) or trailing/missing commas, in VisualEditor or the 2017 wikitext editor (JavaScript-based editors).

"Syntax error in JSON" shows if you attempt to save such code in VisualEditor or the 2017 wikitext editor, while "Bad JSON format" shows if you attempt to open up such code in the TemplateData GUI editor, on template pages.

This error can come up quite frequently while editing a template's TemplateData. The most common mistakes that cause this error include excess commas (such as trailing commas), missing commas and missing quotation marks.

Examples of trailing commas:
<templatedata>
{
    "description": "",
    "format": "inline",
    "params": {
        "1": {
            "label": "",
            "description": "",
            "type": "", // <-- This comma shouldn't be here.
        }, // <-- This comma shouldn't be here.
    }, // <-- This comma shouldn't be here.
}
</templatedata>
Examples of missing commas:
<templatedata>
{
    "description": "",
    "format": "inline" // <-- A comma should be here.
    "params": {
        "1": {
            "label": "",
            "description": "" // <-- A comma should be here.
            "type": ""
        }
    }
}
</templatedata>
Example of missing quotation marks:
"description": An example description // <-- This text should have quotation marks.

To fix these errors, you can either look for the errors in the code yourself, or you can enter the JSON block into an external JSON validator, such as JSONLint, and it will highlight the problematic commas and keys that should be removed.

Due to a longstanding bug, users using the 2010 wikitext editor are able to save pages that have such invalid JSON (details: task T128029), as the JavaScript parser is less strict and allows invalid JSON.

Required property "paramOrder(number)" not found.

This error occurs if you state a parameter in "params" that is not stated in "paramOrder". The number in the square brackets refers to the parameter in "paramOrder" that is missing. It refers to its order in the sequence, but it is one less than its actual position, since "paramOrder" is an array; 0 is the first one, 1 is the second, etc.

"params": {
    "date": { ...
    },
    "reason": { ...
    },
    "talk": { ... // <-- This parameter is not stated in "paramOrder", but it should be.
    }
},
"paramOrder": [
	"date",
	"reason"
]

// Error: Required property "paramOrder[2]" not found.

To fix this, make sure all parameters stated in "params" are listed in "paramOrder". Alternatively, you can remove the "paramOrder" object to remove this error.

Invalid value for property "paramOrder(number)".

This error occurs if you state a parameter in "paramOrder" that is not stated in "params". The number in the square brackets refers to the parameter in "paramOrder" that shouldn't be there. It refers to its order in the sequence, but it is one less than its actual position, since "paramOrder" is an array; 0 is the first one, 1 is the second, etc.

"params": {
    "date": { ...
    },
    "talk": { ...
    }
},
"paramOrder": [
	"date",
	"reason", // <-- This parameter is not stated in "params", but it should be.
    "talk"
]

// Error: Invalid value for property "paramOrder[1]".

To fix this, make sure all parameters stated in "paramOrder" are listed in "params". Alternatively, you can remove the "paramOrder" object to remove this error.

Property "params.parametername.required" is expected to be of type "boolean".

This error occurs if you put quotation marks around the value of either "required" or "suggested".

"suggested": "true" // <-- These quotation marks shouldn't be here.

These are boolean values, not strings, therefore they require no quotation marks. To fix this, remove any quotation marks around the values true or false for these parameters.

Property "format" is expected to be ...

If the "format" parameter exists but its value is not "inline", "block" or a valid format string, you will see the error message "Property "format" is expected to be "inline", "block", or a valid format string."

"format": "notinline"

// Error : Property "format" is expected to be "inline", "block", or a valid format string.

To fix this, make sure the value after "format": equals "inline" or "block" and that there no spelling mistakes. Alternatively, if it's wikitext, make sure it contains a minimum of {{_|_=_}} and that there are no mistakes in the syntax that would normally cause a template to fail, such as duplicate equals signs or missing/duplicate curly brackets; see the section #Custom formats for the syntax for custom formats. Alternatively, you can remove the "format" parameter to remove this error.

Unexpected property "parametername".

This error occurs if you state a parameter that does not exist in TemplateData. This is probably due to spelling mistakes.

<templatedata>
{
    "description": "",
    "format": "inline",
    "params": {
        "1": {
            "label": "",
            "descriptino": "", // <-- spelling mistake
            "type": ""
        }
    }
}
</templatedata>

It also occurs if you state a parameter in any TemplateData object that is not a parameter of that object. This may be due to spelling mistakes, or you may have written the parameter of one TemplateData object under another object that it doesn't belong to.

For example, you might have written the parameter "label" under the root TemplateData object instead of inside "params":

<templatedata>
{
    "description": "",
    "format": "inline",
    "label": "", // <-- incorrectly placed parameter
    "params": {
        "1": { // ↓ it should be in here
            "description": "",
            "type": ""
        }
    }
}
</templatedata>

Alternatively, if the unexpected parameter is under a template parameter inside "params", you'll see its name after "params.parametername." in the error.

To fix this, make sure there aren't any spelling mistakes in the parameter names, and make sure your parameters are in their correct location. Additionally, make sure you don't state any parameters that don't exist for a TemplateData object. You can check which parameters exist for an object in the section #TemplateData parameters.

Required property "params" not found.

This error occurs if there is no "params" object in the TemplateData. This is a necessary object, as it contains all the details of each parameter, so to fix this error, make sure it's added and that there are no spelling mistakes. See the section above on how to add the "params" parameter.

Limitations and feedback

  • Missing features – TemplateData is an example of a tool that was made available with few features, in hope that users would help to guide development of features that they desired. If you'd like to request new features for TemplateData, please let us know.
  • Delays in showing in templates – After adding TemplateData to a template, the metadata should be visible immediately when the template is opened in the visual editor. However, it is possible that it will take several hours before the metadata will show. You can force an update by making a null edit to the template page itself (not the documentation subpage). To perform a null edit, open the template page for editing, and save the page without making any change and without adding any edit summary.
  • Current issues – A list of current bugs and feature requests is available in the Wikimedia bug tracker.

Other tools

Help:Extension:TemplateWizard
A toolbar dialog window for entering template wikitext via an form built from TemplateData.
TemplateData Wizard
A tool that generates TemplateData through an interactive interface.
Skeleton TemplateData generator
A tool that reads the source wikicode of a template, tries to find all the parameters used and outputs a skeleton document with the parameters listed.
JSONLint
A tool that allows you to validate manually-written JSON to help find errors in the syntax.