ListViewProcessCurrentObjectController.CustomHandleProcessSelectedItem Event

Occurs when an end-user double-clicks an object or presses Enter for a selected object in a WinForms application or clicks an object in a Web application in a List Editor.

Namespace: DevExpress.ExpressApp.SystemModule

Assembly: DevExpress.ExpressApp.v24.1.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

public event EventHandler<HandledEventArgs> CustomHandleProcessSelectedItem

VB.NET

Public Event CustomHandleProcessSelectedItem As EventHandler(Of HandledEventArgs)

Event Data

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

Property	Description
Handled	Gets or sets a value that indicates whether the event handler has completely handled the event or whether the system should continue its own processing.

Remarks

Subscribe to the CustomHandleProcessSelectedItem event to change how XAF processes a List Editor’s object when a user attempts to open the object.

XAF opens the selected object’s Detail View if the object is in a List View. If an end-user selects an object in a Lookup List View, XAF links the object to the current Detail View’s object. To cancel this default processing, create the CustomHandleProcessSelectedItem event handler and set the HandledEventArgs.Cancel parameter to true. You can also use the handler to execute an Action - for example, to open a View for the selected object.

The EmployeeLookupListViewController below changes the default behavior for certain employees in a Lookup List View. If an employee is on leave, the end-user cannot link the employee to the current object, and the employee’s Detail View opens. Otherwise, the end-user can link the employee to the master object.

C#

using DevExpress.ExpressApp;
using DevExpress.ExpressApp.SystemModule;
using System.ComponentModel;
// ...
public class EmployeeLookupListViewController : ViewController {
    private ListViewProcessCurrentObjectController processCurrentObjectController;
    private OpenObjectController openObjectController;

    public EmployeeLookupListViewController() {
        TargetViewId = "Employee_LookupListView";
    }
    protected override void OnActivated() {
        base.OnActivated();
        processCurrentObjectController = Frame.GetController<ListViewProcessCurrentObjectController>();
        openObjectController = Frame.GetController<OpenObjectController>();
        if(processCurrentObjectController != null) {
          processCurrentObjectController.CustomHandleProcessSelectedItem += EmployeeLookupListViewController_CustomHandleProcessSelectedItem;
        }
    }
    private void EmployeeLookupListViewController_CustomHandleProcessSelectedItem(
        object sender, HandledEventArgs e) {
        Employee currentEmployee = (Employee)View.CurrentObject;
        if(currentEmployee.IsOnLeave) {
          e.Handled = true;
          if(openObjectController != null) {
            openObjectController.SetObjectToOpen(View.CurrentObject);
            if(openObjectController.OpenObjectAction.Active && openObjectController.OpenObjectAction.Enabled) {
              openObjectController.OpenObjectAction.DoExecute();
            }
          }
        }
    }
    protected override void OnDeactivated() {
        base.OnDeactivated();
        if(processCurrentObjectController != null) {
          processCurrentObjectController.CustomHandleProcessSelectedItem -= EmployeeLookupListViewController_CustomHandleProcessSelectedItem;
          processCurrentObjectController = null;
        }
        openObjectController = null;
    }
}

VB.NET

Imports DevExpress.ExpressApp
Imports DevExpress.ExpressApp.SystemModule
Imports System.ComponentModel
' ...
Public Class EmployeeLookupListViewController
    Inherits ViewController

    Private _processCurrentObjectController As ListViewProcessCurrentObjectController
    Private _openObjectController As OpenObjectController

    Public Sub New()
        TargetViewId = "Employee_LookupListView"
    End Sub

    Protected Overrides Sub OnActivated()
        MyBase.OnActivated
        Me._processCurrentObjectController = Frame.GetController(Of ListViewProcessCurrentObjectController)
        Me._openObjectController = Frame.GetController(Of OpenObjectController)
        If (Not (Me._processCurrentObjectController) Is Nothing) Then
            AddHandler Me._processCurrentObjectController.CustomHandleProcessSelectedItem, AdressOf EmployeeLookupListViewController_CustomHandleProcessSelectedItem
        End If
    End Sub

    Private Sub EmployeeLookupListViewController_CustomHandleProcessSelectedItem(ByVal sender As Object, ByVal e As HandledEventArgs)
        Dim currentEmployee As Employee = CType(View.CurrentObject,Employee)
        If currentEmployee.IsOnLeave Then
            e.Handled = true
            If (Not (Me._openObjectController) Is Nothing) Then
                Me._openObjectController.SetObjectToOpen(View.CurrentObject)
                If (Me._openObjectController.OpenObjectAction.Active AndAlso Me._openObjectController.OpenObjectAction.Enabled) Then
                    Me._openObjectController.OpenObjectAction.DoExecute
                End If
            End If
        End If
    End Sub
    Protected Overrides Sub OnDeactivated()
        MyBase.OnDeactivated
        If (Not (Me._processCurrentObjectController) Is Nothing) Then
            RemoveHandler Me._processCurrentObjectController.CustomHandleProcessSelectedItem, AddressOf EmployeeLookupListViewController_CustomHandleProcessSelectedItem
            Me._processCurrentObjectController = Nothing
        End If
        Me._openObjectController = Nothing
    End Sub
End Class