Null (query directive)

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Description

Returns then null value

Constructor

Null()

Examples 

Following example gets the superclass of input topic or null if it does not have a superclass.

importPackage(org.wandora.query2);
importPackage(org.wandora.topicmap);
new If(
  new Players(XTMPSI.SUPERCLASS_SUBCLASS,XTMPSI.SUPERCLASS)
  .whereInputIs(XTMPSI.SUBCLASS),
  new Players(XTMPSI.SUPERCLASS_SUBCLASS,XTMPSI.SUPERCLASS)
  .whereInputIs(XTMPSI.SUBCLASS),
  new Null().as(XTMPSI.SUPERCLASS)
)
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