Parallel Computing

Page text variables are string variables created in the wiki text of a page, and can be automatically made available for inclusion in other pages.
In the default installation, PageTextVariables can only have a name containing basic Latin/Roman (ASCII) letters, digits, dash and underscore (meaning regular PTVs don't have accented characters). This is a limitation for international wikis (experimental recipe for international PTV : Cookbook:InternationalPTVs).

Defining Page Text Variables

There are three ways to define automated Page Text Variables (more patterns can be defined if needed) :

• use a definition list - the normal pmwiki markup for a definition list will create a page text variable

:Name: Crisses
"{$:Name}"

• use a simple colon delimiter in normal text

Address: 1313 Mockingbird Lane

"{$:Address}"

• hidden directive form - PmWiki markup that doesn't render on the page, but defines the variable

(:Country: Transylvania :)
"{$:Country}"

Default values for unset or empty Page Text Variables

If a page text variable is not defined in a page, or if the current visitor doesn't have read permissions for the page containing the variable definition, then the markup to access the variable like {$:Country} will return an empty string.

An administrator can define default values for such cases (PmWiki 2.2.121+). The following arrays can be defined in local/config.php:

  $DefaultUnsetPageTextVars = array(
    'SpecificVariable' => 'SpecificVariable is unset',
    '*PartialMatch*' => 'some value',
    '*' => '(unset)',
  );

  $DefaultEmptyPageTextVars = array(
    'SpecificVariable' => 'SpecificVariable is set, but empty',
    '*' => '(empty)',
  );

In the above examples, {$:SpecificVariable} or {OtherPage$:SpecificVariable} will output the value defined:

• in $DefaultUnsetPageTextVars if the variable is not defined in the page text, or if the user doesn't have read permissions for OtherPage
• in $DefaultEmptyPageTextVars if the user has read permissions, and the variable is defined but empty, for example (:SpecificVariable::).

The patterns are processed in order, and the first matching pattern assigns the value to the variable. The asterisk * matches any string, in the above examples an undefined variable that doesn't match 'SpecificVariable' or '*PartialMatch*' will output '(unset)'.

Usage

Usage on the same page

On the same page you can resolve page text variables through the {$:Var} format (shown above).

Usage in headers and footers: special references

If you want a GroupHeader, GroupFooter, SideBar, etc to call on page text variable in the main page, you need to include special reference information. To explicitly reference the page text variable from the page being displayed add an asterisk to the page text variable's markup: {*$:Address} on the GroupFooter or GroupHeader page.

{*$:Mountain} \\
{*$Namespaced}

To include a page text variable from a header or footer see usage from other pages below.

Usage from other pages

If you want to pull the data from another page, use the {Group/PageName$:Var} format.

Suburb: Khandallah
(:Lake:Taupo:)
:Mountain:Mt Ruapehu

->"{PmWiki/PageTextVariables$:Suburb}"
->"{{$FullName}$:Lake}"
->"{PmWiki/PageTextVariables$:Mountain}"

Usage from included pages

Page text variables are never included from their source page. See Usage from other pages above to refer to a page text variable on another page.

Usage with pagelists

Page lists can also access the page text variables:

(:pagelist group=PmWiki order=$:Summary count=6 fmt=#singleline:)

And to create pagelist formats (such as those documented at Site.Page List Templates, Page Lists, Page List Templates, Page Variables. Store custom pagelists at Site.Local Templates).

Page lists can also use page text variables to select pages :

(:pagelist group=PmWiki $:City=Paris count=8 fmt=#singleline order=-name:)

(:pagelist group=PmWiki $:City="Addis Ababa,Paris" order=-$:Version count=8 fmt=#singleline:)

• When using page text variables for selection or ordering, don't put the curly braces around the variable name. The curly forms do a replacement before the pagelist command is evaluated.
• Link markup within the contents of a hidden page text variable directive (as opposed to other ways of specifying PTVs) will not be cached as a link on the page and thus won't be seen by pagelist's link= option. If you want the link to be found by link=, you need to specify the PTV using non-directive markup, or else put the link on the page even if it's hidden within a false conditional: (:Linkme: [[PageToLink]]:) (:if false:){$:Linkme}(:ifend:)

The page text variable value is always the text that is written in the page. It is only evaluated when the variable is printed/output to HTML. To sort by a page text variable variable, all values in all pages are the not-yet-evaluated text strings, and the pagelist order function does what it can with them. It does not process/evaluate the text at this point.

E.g. With a page name in to format "yyyyMonth" it is simpler to use a PageVariable calculated in config.php, not a PageTextVariable:

Then use (:pagelist order=$NameToYearMonth:)

An alternative is writing in the wiki page:

as the markup expression that follows won't work:

Testing if set or not set within a pagelist

Tip : (:if ! equal "{$:PTV}" "":) will test if PTV is empty/unset or not.

(:pagelist group=PmWiki $:Summary=-?* count=6  fmt=#singleline:)

Use page text variable in a template

Display pages by Audience page text variable.

>>comment<<
[[#byaudience]]
(:if ! equal '{=$:Audience}' '{<$:Audience}':)
-<'''{=$:Audience}''':  
(:ifend:)
[[{=$Name}]]
[[#byaudienceend]]
>><<
(:pagelist group=PmWiki count=10 fmt=#byaudience order=-$:Audience:)

Use page text variables in conditional markup

Page text variables will be assigned/evaluated before any conditional markup is evaluated. This effectively means that you cannot declare a PTV within an if...else condition; and also that a PTV will have a value even if it is set within a (:if false:)....(:ifend:) condition.

Usage - from within code (developers only)

The standard PageVar($pagename,$varname) function can return page text variables, but remember to include the dollar and colon like this:

It works by caching all page (text) variables it finds in a page (in $PCache) and returns the one requested.