Changes
The correspondence between Queries and its items is created and stored by a relationship (“QUERYRELATION”). Therefore a single QueryItem can be used several times for different Queries.
==Content queries==
We often face the need to fetch a list of objects meeting arbitary criteria, for example for
* scanning of ID markers (QR-Code, Barcode, …)
* show objects from deeper hierarchy levels
Storing of data permanently on the device would need too much resources, hence we load the objects from server on demand. Characteristics of a content query are
* derivative from QUERY classified as SYSCLS_QUERY marks instances as content queries
* Related to instances via relations
* Placed in view hierarchy defined via view items
* Require context scopes on client side
Configuration of a content query requies
* Set filter object (FILTEROBJECT) similar as for other query
* Create a proper relation
* Create a query view item and set the instance as QUERY
* Create a relation view item and set the according default MetaClass and relation
* Create and relate a query context scope and set the instance as QUERY
* For the scope define the MetaProperties, which should be available as filter criteria on the client. Without appropriate query item, equality is used as filter operator (=)
== Usage of DatabaseViews ==
It is also possible to define a Database View and use this View for the evaluation of Queries (see [[VirtualContentClass]]).
[[Category:UBIK Object]]
