ArcObjects Library Reference (GeoDatabase)  

ITopologyClassEvents.OnValidate Event

This event is fired when the topology containing the class is validated.

[Visual Basic .NET]
Public Event OnValidate As OnValidateEventHandler
public event OnValidateEventHandler OnValidate
HRESULT OnValidate(
  IGeometry* validatedArea


validatedArea [in]

  validatedArea is a parameter of type IGeometry

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.


The OnValidate event is fired each time a dirty area is validated in the topology in which the class is participating.  Handlers are provided with an IGeometry object corresponding to the dirty areas that were validated. The IGeometry object may represent a single or multi-part polygon or a collection of polygons.

In some cases, using the OnValidate method on feature classes in a Topology may result in a situation where the Topology will always have a Dirty Area such as if the purpose of listening to the OnValidate event is to act on another feature class in the Topology and perform some action on the features in that class. 

For example, an extension that listens to the OnValidate event in order to derive features for a feature class by aggregarting the features in the class that is validated.  If the dervied features are in a feature class that is in the Topology, the result of the OnValidate event will be a Topology that will always contain a dirty area. The derived feature class should not be in the topology in order for this example to be applicable.

See Also

ITopologyClassEvents Interface