How to: Deactivate (Hide) an Action in Code

• Sep 09, 2020
• 2 minutes to read

An Action’s visibility is managed by the ActionBase.Active property. When this property returns false, an action is invisible. Follow the steps below to deactivate a predefined or custom action. In the current example, the Delete action will be disabled.

• Create the DeactivateDeleteController Controller. To learn how to do this, refer to the Controller Class article.

• Override its OnActivated method as shown below. This method is executed after the Action’s activation and raises the Controller.Activated event.

  C#

  using DevExpress.ExpressApp;
  using DevExpress.ExpressApp.SystemModule;
  // ...
  public partial class DeactivateDeleteController : ObjectViewController {
      private const string Key = "Deactivation in code";
      DeleteObjectsViewController DeleteController;
  
      public DeactivateDeleteController() {
          InitializeComponent();
      }
  
      protected override void OnActivated() {
          base.OnActivated();
          DeleteController =
              Frame.GetController<DeleteObjectsViewController>();
  
          if(DeleteController != null) {
              DeleteController.Active[Key] =
                  !(View.ObjectTypeInfo.Type == typeof(Contact) && View is ListView);
          }
      }
  
      protected override void OnDeactivated() {
          if(DeleteController != null) {
              DeleteController.Active.RemoveItem(Key);
              DeleteController = null;
          }
          base.OnDeactivated();
      }
  }
  

  VB.NET

  Imports DevExpress.ExpressApp
  Imports DevExpress.ExpressApp.SystemModule
  ' ...
  Partial Public Class DeactivateDeleteController
      Inherits ObjectViewController
  
      Private Const Key As String = "Deactivation in code"
      Private DeleteController As DeleteObjectsViewController
  
      Public Sub New()
          InitializeComponent()
      End Sub
  
      Protected Overrides Sub OnActivated()
          MyBase.OnActivated()
          DeleteController = Frame.GetController(Of DeleteObjectsViewController)()
  
          If DeleteController IsNot Nothing Then
              DeleteController.Active(Key) = Not(View.ObjectTypeInfo.Type Is GetType(Contact) AndAlso TypeOf View Is ListView)
          End If
      End Sub
  
      Protected Overrides Sub OnDeactivated()
          If DeleteController IsNot Nothing Then
              DeleteController.Active.RemoveItem(Key)
              DeleteController = Nothing
          End If
          MyBase.OnDeactivated()
      End Sub
  End Class
  

  In the code above, a false or true value is added to the Active BoolList of the DeleteObjectsViewController. As a result, the Controller’s Actions will be hidden from the Views for which the false value is added (Contact List Views in this example). This approach is similar to the Controller’s ViewController.TargetObjectType and ViewController.TargetViewType properties, but they are not applicable here because enabling a disabled controller does not occur automatically on a View change.

Note

XAF provides other ways to deactivate an action that might be more appropriate for your scenario. Refer to the ActionBase.Active topic to learn more.

Refer to the Determine an Action’s Controller and Identifier topic to learn how to determine which Controller provides the Action to be hidden or deactivated.

To learn about the ways to access the existing controller’s properties in code, refer to the Customize Controllers and Actions article.