
82 vFoglight
Web Component Guide
Hide Root
The Hide Root checkbox is enabled only if Root Query is checked. If checked, when
the results of the root query are shown in the Data Browser or the Data tab of a Portal or
Report Builder, the first item in the results list is hidden. If the query results list does not
contain one item, then this option is ignored. This is useful when you know that the
results of the query will always return one item and you want to save users from having
to expand the node corresponding to the sole item in order to see its children. For
example, if you have a query that returns the root of a data source, hiding that root is
useful so that users can more easily get to the data that is really of interest.
Aggregations
A query returns a list of data objects. Instead of directly returning these data objects, the
Aggregations settings creates new data objects that contain only aggregated values. For
example, if a query returns a set of alarms, you can replace these data objects with an
Alarm data object containing the maximum severity of those alarms.
Note In most cases, the list contains only one aggregated data object.
Aggregation data objects are of the given data-object type, and they contain aggregated
values of certain properties within the data objects. The aggregation types are:
•Maximum
• Minimum
•Sum
• Average
• Weighted Average
• Count
Unlike the other aggregation types, a count aggregation returns a Count data object with
only two properties:
• Value - the count of returned data objects
• TypeName - the name of the type of data object being selected by the query and
counted
Count is also different from the other aggregation types in how it handles a query that
does not return any data objects. The other types will not create an aggregated object in
this case. Count does create an aggregated object, with Value set to 0.
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