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TreeListView.ValidateNode Event

Enables you to specify whether the focused node's data is valid, and whether the node can lose focus.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v19.2.dll


public event TreeListNodeValidationEventHandler ValidateNode
Public Event ValidateNode As TreeListNodeValidationEventHandler

Event Data

The ValidateNode event's data class is TreeListNodeValidationEventArgs. The following properties provide information specific to this event:

Property Description
Culture Gets the culture related to the validation. Inherited from ValidationEventArgs.
ErrorContent Gets or sets an object that describes the validation error. Inherited from ValidationEventArgs.
ErrorType Gets or sets the error type. Inherited from ValidationEventArgs.
Handled Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. Inherited from RoutedEventArgs.
IsValid Gets or sets a value specifying whether the value is valid. Inherited from ValidationEventArgs.
Node Gets the processed node.
OriginalSource Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs.
RoutedEvent Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs.
Row Gets the processed row. Inherited from GridRowValidationEventArgs.
RowHandle Gets the processed row's handle. Inherited from GridRowValidationEventArgs.
Source Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.
UpdateSource Gets the action that caused the validation. Inherited from ValidationEventArgs.
Value Gets the editor's value. Inherited from ValidationEventArgs.

The event data class exposes the following methods:

Method Description
InvokeEventHandler(Delegate, Object) When overridden in a derived class, provides a way to invoke event handlers in a type-specific way, which can increase efficiency over the base implementation. Inherited from RoutedEventArgs.
OnSetSource(Object) When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. Inherited from RoutedEventArgs.
SetError(Object) Displays an error within the editor. Inherited from ValidationEventArgs.
SetError(Object, ErrorType) Displays an error within the editor. Inherited from ValidationEventArgs.


Node validation is performed within the ValidateNode event handler. This event is automatically fired when a node is about to lose focus. To manually force node validation, call the DataViewBase.CommitEditing method.

The processed node is returned by the event parameter's TreeListNodeValidationEventArgs.Node property. After cell values have been obtained, you can verify whether these values meet your validity criteria. If the node fails validation, set the event's ValidationEventArgs.IsValid parameter to false. Otherwise, leave this parameter set to true.

To learn more, see Row Validation.

See Also