Jump to: navigation, search

QUERY


Revision as of 11:58, 24 March 2015 by KNO (Talk | contribs) (Content query)

IC METACLASS.gif Query
Name QUERY
Namespace System.Query
Internal Name SystemObjects.QUERY
TypeString UBIK.Kernel.MetaClass
RuntimeType UBIK.Kernel.Query
Purpose Configure queries
Version 2+

In UBIK, queries are used for fetching a list of ContentClasses from the database. Queries use data base mechanism for perfomant data access and will deliver a list of objects of a certain Metaclass. Queries can be used in different scenarios:

  • data fetching (n records)
  • finding a single or a set of recordset(s)
  • used as definition of root nodes in a View
IC Hint square.pngThere are specific methods available for this type!

Query and QueryItems

A Query is defined for a single MetaClass, where the MetaClass is defined in the property FILTEROBJECT. Once a query is evaluated it will deliver a list of objects of type ContentClasses (instances), filtered as defined by its QueryItems. The correspondence between Queries and its items is created and stored by a relationship SYSREL QUERY. Therefore a single QueryItem can be used several times for different Queries.

Content query

Objects can be loaded on demand from the server, as storing a huge amount of data permanently on the device would need too much resources.

A content query is a QUERY instance classified as SYSCLS QUERY and can be related to other content objects. For being shown in the View hierarchy it is necessary to create a QueryViewItem for the query object itself.

Further on, for being published to the client a Query Scopes has to be created and added to the ACM.

The result of the query depends on the network connection and the UBIK® sync mode, but follows the same rules as Searching for objects by Optical codes.

Scan query

Usage of DatabaseViews

It is also possible to define a Database View and use this View for the evaluation of Queries (see VirtualContentClass).

See also