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Special property "Has uniqueness constraint"
|Has uniqueness constraint|
Allows to restrict value annotation to be unique
|Provided by:||extension "Semantic MediaWiki "Semantic MediaWiki (SMW) is a free, open-source extension to MediaWiki that lets you store and query data within the wiki's pages. Semantic MediaWiki is also a full-fledged framework, in conjunction with many spinoff extensions, that can turn a wiki into a powerful and flexible knowledge management system. All data created within SMW can easily be published via the Semantic Web, allowing other systems to use this data seamlessly.|
|Removed:||still in use|
|Alias:||has no alias|
|In this wiki:||Property:Has uniqueness constraint|
The "Has uniqueness constraint" property is a special property in Semantic MediaWiki which got introduced with Semantic MediaWiki 2.4.0Released on 9 July 2016 and compatible with MW 1.19.0 - 1.27.x.1 and will indicates that value assignments (annotations) to a property are expected to be unique. i.e. a specific data value for the respective property can only be added to one page. Semantic MediaWiki 2.5.0Released on 14 March 2017 and compatible with MW 1.23.0 - 1.29.x.2 made this feature more strict to only allow a data value for the respective property be added once.
Features and limitations
- Feature is not enabled by default (See the help page on configuration parameter
$smwgDVFeaturesSets the available features regarding property data values for details on configuring Semantic MediaWiki for special data value features including "Has uniqueness constraint" with the
owl:FunctionalProperty34 is added to the RDF export that extends the property specification with the
Has uniqueness constraintattribute
Add the following code to the property page:
[[Has uniqueness constraint::true]]
- Page "Q1339" on <sandbox.semantic-mediawiki.org>
- Property page "NDL ID" on <sandbox.semantic-mediawiki.org>
- Pull request example "2113" on <sandbox.semantic-mediawiki.org>
- Semantic MediaWiki: GitHub pull request gh:smw:1463
- Semantic MediaWiki: GitHub pull request gh:smw:2113
- Semantic MediaWiki: GitHub pull request gh:smw:2167
- "A functional property is a property that can have only one (unique) value y for each instance x, i.e. there cannot be two distinct values y1 and y2..." described by https://www.w3.org/TR/2004/REC-owl-ref-20040210/#FunctionalProperty-def