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TWiki Meta Data

Additional topic data, program-generated or from TWikiForms, is stored in META variable name/value pairs

Overview

TWikiMetaData uses META variables to store topic data that's separate from the main free-form content. This includes program-generated info like FileAttachment and topic movement data, and user-defined TWikiForms info. Use META variables to format and display Meta Data.

Meta Data Syntax

• Format is the same as in TWikiVariables, except all fields have a key.
  • %META:<type>{key1="value1" key2="value2" ...}%

• Order of fields within the meta variables is not defined, except that if there is a field with key name, this appears first for easier searching (note the order of the variables themselves is defined).

• Each meta variable is on one line.

• \n (new line) is represented in values by %_N_ and " (double-quotes) by %_Q_%.

Example of Format

%META:TOPICINFO{version="1.6" date="976762663" author="PeterThoeny" format="1.0"}%
   text of the topic
%META:TOPICMOVED{from="Codev.OldName" to="Codev.NewName"
   by="JohnTalintyre" date="976762680"}%
%META:TOPICPARENT{name="NavigationByTopicContext"}%
%META:FILEATTACHMENT{name="Sample.txt" version="1.3" ... }%
%META:FILEATTACHMENT{name="Smile.gif" version="1.1" ... }%
%META:FORM{name="WebFormTemplate"}%
%META:FIELD{name="OperatingSystem" value="OsWin"}%
%META:FIELD{name="TopicClassification" value="PublicFAQ"}%

Meta Data Specifications

The current version of Meta Data is 1.0, with support for the following variables.

META:TOPICINFO

META:TOPICMOVED

This is optional, exists if topic has ever been moved. If a topic is moved more than once, only the most recent META:TOPICMOVED meta variable exists in the topic, older ones are to be found in the rcs history.

%META:TOPICMOVED{from="Codev.OldName" to="Codev.NewName" by="talintj" date="976762680"}%

Notes:

• at present version number is not supported directly, it can be inferred from the RCS history.
• there is only one META:TOPICMOVED in a topic, older move information can be found in the RCS history.

META:TOPICPARENT

META:FILEATTACHMENT

Extra fields that are added if an attachment is moved:

META:FORM

META:FIELD

Should only be present if there is a META:FORM entry. Note that this data is used when viewing a topic, the form template definition is not read.

Recommended Sequence

There is no absolute need for Meta Data variables to be listed in a specific order within a topic, but it makes sense to do so a couple of good reasons:

• form fields remain in the order they are defined
• the diff function output appears in a logical order

The recommended sequence is:

• META:TOPICINFO
• text of topic
• META:TOPICMOVED (optional)
• META:TOPICPARENT (optional)
• META:FILEATTACHMENT (0 or more entries)
• META:FORM (optional)
• META:FIELD (0 or more entries; FORM required)

Viewing Meta Data in Page Source

When viewing a topic the Raw Text link can be clicked to show the text of a topic (i.e., as seen when editing). This is done by adding raw=on to URL. raw=debug shows the meta data as well as the topic data, ex: debug view for this topic

Rendering Meta Data

Meta Data is rendered with the %META% variable. This is mostly used in the view, preview and edit scripts.

Note: Rendering meta data is currently not supported in topic text. As a workaround, use FormattedSearch on the current topic only to render form fields.

Current support covers:

Variable usage:	Comment:
%META{"attachments"}%	Show attachments, except for hidden ones. Options: all="on": Show all attachments, including hidden ones.
%META{"form"}%	Show form data, see TWikiForms.
%META{"formfield"}%	Show form field value. Parameter: name="field_name". Example: %META{ "formfield" name="TopicClassification" }%
%META{"moved"}%	Details of any topic moves.
%META{"parent"}%	Show topic parent. Options: dontrecurse="on": By default recurses up tree, at some cost. nowebhome="on": Suppress WebHome. prefix="...": Prefix for parents, only if there are parents, default "". suffix="...": Suffix, only appears if there are parents, default "". separator="...": Separator between parents, default is " > ".

Known Issues

At present, there is no Meta Data support for Plugins. However, the format is readily extendable and the Meta.pm code that supports the format needs only minor alteration.

-- TWiki:Main.JohnTalintyre - 29 Aug 2001
-- TWiki:Main.MikeMannix - 03 Dec 2001
-- TWiki:Main.PeterThoeny - 10 Jan 2002