ShowNavigationItemController.CustomUpdateSelectedItem Event

Occurs when the ShowNavigationItemController.ShowNavigationItemAction‘s selected item is about to change, to reflect the change of the active View.

Namespace: DevExpress.ExpressApp.SystemModule

Assembly: DevExpress.ExpressApp.v23.2.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

public event EventHandler<CustomUpdateSelectedItemEventArgs> CustomUpdateSelectedItem

VB.NET

Public Event CustomUpdateSelectedItem As EventHandler(Of CustomUpdateSelectedItemEventArgs)

Event Data

The CustomUpdateSelectedItem event's data class is DevExpress.ExpressApp.SystemModule.CustomUpdateSelectedItemEventArgs.

Remarks

This event is raised by the ShowNavigationItemController.UpdateSelectedItem method. Handle this event to perform specific actions when the ShowNavigationItemAction‘s selected item is about to change. You can perform the change of the selected item in a custom way. In this instance, set the event handler’s CustomUpdateSelectedItemEventArgs.Handled parameter to true.

The following example specifies the selected item:

C#

using DevExpress.ExpressApp;
using DevExpress.ExpressApp.SystemModule;

namespace MainDemo.Module {
    public class SelectedNavigationItemController : WindowController {
        public SelectedNavigationItemController() {
            TargetWindowType = WindowType.Main;
        }
        protected override void OnActivated() {
            base.OnActivated();
            Frame.GetController<ShowNavigationItemController>().CustomUpdateSelectedItem += SelectedNavigationItemController_CustomUpdateSelectedItem;
            Application.ViewShowing += Application_ViewShowing;
        }
        bool cancelSelectedNavigationItemChange;
        private void Application_ViewShowing(object sender, ViewShowingEventArgs e) {
            if (e.View.Id == "Employee_DetailView" && e.SourceFrame?.View?.Id == "Person_ListView") {
                cancelSelectedNavigationItemChange = true;
            }
        }
        private void SelectedNavigationItemController_CustomUpdateSelectedItem(object sender, CustomUpdateSelectedItemEventArgs e) {
            if (cancelSelectedNavigationItemChange) {
                cancelSelectedNavigationItemChange = false;
                e.Handled = true;
                e.ProposedSelectedItem = ((ShowNavigationItemController)sender).ShowNavigationItemAction.SelectedItem;
            }
        }
        protected override void OnDeactivated() {
            base.OnDeactivated();
            Frame.GetController<ShowNavigationItemController>().CustomUpdateSelectedItem -= SelectedNavigationItemController_CustomUpdateSelectedItem;
            Application.ViewShowing -= Application_ViewShowing;
        }
    }
}

VB.NET

Imports DevExpress.ExpressApp
Imports DevExpress.ExpressApp.SystemModule

Namespace MainDemo.Module
    Public Class SelectedNavigationItemController
        Inherits WindowController

        Public Sub New()
            TargetWindowType = WindowType.Main
        End Sub

        Protected Overrides Sub OnActivated()
            MyBase.OnActivated()
            Frame.GetController(Of ShowNavigationItemController)().CustomUpdateSelectedItem += AddressOf SelectedNavigationItemController_CustomUpdateSelectedItem
            Application.ViewShowing += AddressOf Application_ViewShowing
        End Sub

        Private cancelSelectedNavigationItemChange As Boolean

        Private Sub Application_ViewShowing(ByVal sender As Object, ByVal e As ViewShowingEventArgs)
            If e.View.Id Is "Employee_DetailView" AndAlso e.SourceFrame?.View?.Id Is "Person_ListView" Then
                cancelSelectedNavigationItemChange = True
            End If
        End Sub

        Private Sub SelectedNavigationItemController_CustomUpdateSelectedItem(ByVal sender As Object, ByVal e As CustomUpdateSelectedItemEventArgs)
            If cancelSelectedNavigationItemChange Then
                cancelSelectedNavigationItemChange = False
                e.Handled = True
                e.ProposedSelectedItem = CType(sender, ShowNavigationItemController).ShowNavigationItemAction.SelectedItem
            End If
        End Sub

        Protected Overrides Sub OnDeactivated()
            MyBase.OnDeactivated()
            Frame.GetController(Of ShowNavigationItemController)().CustomUpdateSelectedItem -= AddressOf SelectedNavigationItemController_CustomUpdateSelectedItem
            Application.ViewShowing -= AddressOf Application_ViewShowing
        End Sub
    End Class
End Namespace