TreeListView.NodeExpanding Event

Occurs before a node is expanded.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v14.2.dll

Declaration

C#

public event TreeListNodeAllowEventHandler NodeExpanding

VB.NET

Public Event NodeExpanding As TreeListNodeAllowEventHandler

Event Data

The NodeExpanding event's handler receives an argument of the TreeListNodeAllowEventArgs type. The following properties provide information specific to this event:

Property	Description
Allow	Gets or sets whether or not the operation is allowed.
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.
Node	Gets the processed node. Inherited from TreeListNodeEventArgs.
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 TreeListNodeEventArgs.
Source	Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.

Remarks

Handle this event to:

• Cancel the action by setting the event parameter's TreeListNodeAllowEventArgs.Allow property to false;
• Dynamically create child nodes. In this instance, when expanding a node, you do not know whether it has child nodes or not. If the node has no child nodes, hide the expand button by setting the TreeListNode.IsExpandButtonVisible property to false.

After a node has been expanded, the TreeListView.NodeExpanded event is raised.

To learn more, see Expanding and Collapsing Nodes .