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== Basics ==
In UBIK, id marker scan queries are used for fetching a list of [[Contentclass|ContentClasses]] identified by scan code ([http://dev.metaio.com/sdk/tracking-config/optical-tracking/id-marker/ id marker], [http://en.wikipedia.org/wiki/Barcode barcode], [http://en.wikipedia.org/wiki/QRcode qr code]) from the database. All of these objects have to fullfill the classification [[SYSCLS_OBJECTWITHIDMARKER]] in order to be found as the query result. The id marker scan query itself inherits functionality from [[Query|Query]] and has the classification interface [[SYSCLS_IDMARKERSCANQUERY]].
Id marker scan queries can be used in different scenarios with objects identified by scan codes:
* data fetching (n records)
== Relation between Query and Items ==
see [[Query|Query]].
== Classification FilterClass==The IdMarkerScanQuery has FilterCLass is a reference to the root node where all the matching content is beeing compared to the query criteria. The root node itself does not need the classification interface [[SYSCLS_IDMARKERSCANQUERYSYSCLS_OBJECTWITHIDMARKER]]as all derived MetaClasses are recursively checked for implementing the classification interface.All the found content then is aggregated to one query result. {{Attention|When selecting the query root node, please consider that possibly a huge amount of derived MetaClasses has to be recusively cheched for implementing the classification interface! Using a FilterClass that directly implements the interface reduces the processing time to a minimum!}}
[[Category:System MetaClasses]]
[[Category:Queries]]
