Property:Allows value

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Latest revision as of 02:26, 15 April 2011

Allows value is a special property in Semantic MediaWiki with a built-in meaning: it lists one permissible value for a property.

You can use this special property with a property of any datatype to limit its possible values. For example, the page for a Problem severity property might contain:

 [[allows value::Enhancement]],[[allows value::Trivial]],[[allows value::Minor]],
 [[allows value::Normal]],[[allows value::Major]],[[allows value::Critical]]

Ordered properties

Enumerating several Allows value does not put the possible values of a property in that order; properties of Type:String will still sort in alphabetical order. You can ensure alphabetical sort order is appropriate using a prefix, for example:

 [[allows value::a-Enhancement]],[[allows value::b-Trivial]], [[allows value::c-Minor]]...

and then you can query for greater-than-or-equal or less-than-or-equal values, for example [[property name::<c-Minor]]

You can create a property of Type:Number and give it allowed values that are "pseudo-numbers", for example:

 [[Allows value::1 - Low]] [[Allows value::2 - Medium]] [[Allows value::2 - Middling]] ...

SMW's number datatype ignores the "- description" after the number. This gives the set of properties a numerical order and lets you make two values equivalent.