TreeListView.ValidateNodeDeletion Event

Allows you to validate nodes, check database constraints, and delete nodes from the database before a user deletes a node from the Data Grid.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v25.1.dll

NuGet Package: DevExpress.Wpf.Grid.Core

Declaration

C#

public event EventHandler<TreeListValidateNodeDeletionEventArgs> ValidateNodeDeletion

VB.NET

Public Event ValidateNodeDeletion As EventHandler(Of TreeListValidateNodeDeletionEventArgs)

Event Data

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

Property	Description
DisplayErrorMode	Gets or sets whether to display an error message. Inherited from GridValidateRowDeletionEventArgs.
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.
Nodes	Gets nodes a user wants to delete.
OriginalSource	Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs.
Result	Gets or sets information about the error (its type and description). Inherited from GridValidateRowDeletionEventArgs.
ResultAsync	Gets or sets a task that asynchronously deletes rows from the underlying data source (database). Inherited from GridValidateRowDeletionEventArgs.
RoutedEvent	Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs.
RowHandles	Gets handles of rows that a user wants to delete. Inherited from GridValidateRowDeletionEventArgs.
Rows	Gets rows that a user wants to delete. Inherited from GridValidateRowDeletionEventArgs.
Source	Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.

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.

Remarks

CRUD Operations

You can implement CRUD operations (create, read update, delete). These operations allow users to manage data in the Data Grid. Refer to the following topic for more information: Implement CRUD Operations in a Data-Bound Grid.

View Example: How to Implement CRUD Operations in a Data-Bound Grid