Determine an Action's Controller and Identifier

• Dec 14, 2021
• 4 minutes to read

If you wish to customize an Action provided by XAF (or a third-party module), you should know which Controller provides this Action. When the Controller is known, you can override it or access it using the Frame.GetController<ControllerType> method, and handle the required events. In certain cases, you may also require an Action’s identifier (e.g., to create a Conditional Appearance rule). This topic describes how to determine the Controller that hosts a particular Action and how to get the Action identifier.

Determine a Controller and Identifier at Runtime

When you execute an Action in your application, the Action information is displayed in the Visual Studio Output Window (and also is appended to the log file).

04.09.14 11:57:49.966   Execute action
04.09.14 11:57:49.968       Type: DevExpress.ExpressApp.Actions.SingleChoiceAction
04.09.14 11:57:49.970       ID: ChooseSkin
04.09.14 11:57:49.972       Category: Appearance
04.09.14 11:57:49.974       Controller.Name: DevExpress.ExpressApp.Win.SystemModule.ChooseSkinController
04.09.14 11:57:49.975       Context.Name: Contact
04.09.14 11:57:49.976       Context.IsRoot: True
04.09.14 11:57:49.978       Context.SelectedObjects.Count: 0
04.09.14 11:57:49.980       Context.CurrentObject: <not specified>
04.09.14 11:57:49.983       SelectedItem: Visual Studio 2013 Blue
04.09.14 11:57:50.377   Action 'ChooseSkin' done

Here, the Controller.Name value is the name of the executed Action’s Controller and the ID value is the Action’s identifier.

Determine a Controller at Design Time

If you know the Action’s identifier, you can determine the Action’s Controller in the Model Editor using the IModelAction.Controller property of the ActionDesign | Actions | <Action> node. In the Model Editor, Action identifiers (see ActionBase.Id) are used as Action node captions, instead of captions visible in the UI. Thus, to easily locate an Action is the Model Editor, you must know its identifier.

If the identifier is unknown, use the IModelAction.Caption property that specifies the Action caption visible to users to check if this is the Action you are looking for.

Actions Added via the Action Attribute

Actions defined via the ActionAttribute are generated at runtime by the ObjectMethodActionsViewController. Identifiers of these Actions are formed using the following pattern:

<business_class_short_name>.<action_method_name>

If the Action method takes a parameter, then the method parameter type name is also appended.

<business_class_short_name>.<action_method_name>.<parameter_type_short_name>

For instance, to access an Action declared in the Task business class via the MarkCompleted method, use the following code:

C#

using DevExpress.ExpressApp;
using DevExpress.ExpressApp.SystemModule;
using DevExpress.ExpressApp.Actions;
// ...
public class MyViewController : ViewController {
    protected override void OnActivated() {
        base.OnActivated();
        ObjectMethodActionsViewController controller = Frame.GetController<ObjectMethodActionsViewController>();
        if (controller != null) {
            SimpleAction markCompletedAction = controller.Actions["Task.MarkCompleted"] as SimpleAction;
            // ...
        }
        // ...
    }
}

VB.NET

Imports DevExpress.ExpressApp
Imports DevExpress.ExpressApp.SystemModule
Imports DevExpress.ExpressApp.Actions
' ...
Public Class MyViewController
    Inherits ViewController
    Protected Overrides Sub OnActivated()
        MyBase.OnActivated()
        Dim controller As ObjectMethodActionsViewController = Frame.GetController(Of ObjectMethodActionsViewController)()
        If controller IsNot Nothing Then
            Dim markCompletedAction As SimpleAction = TryCast(controller.Actions("Task.MarkCompleted"), SimpleAction)
            ' ...
        End If
        ' ...
    End Sub
End Class

To avoid possible null reference exceptions when accessing an existing Controller from your code, always ensure that the Frame.GetController<ControllerType> method result is not null when the XafApplication.OptimizedControllersCreation property is true.

To access an Action declared in the Task business class via the Postpone method taking the PostponeParametersObject type parameter, use the following code:

C#

using DevExpress.ExpressApp.SystemModule;
using DevExpress.ExpressApp.Actions;
// ...
ObjectMethodActionsViewController controller = Frame.GetController<ObjectMethodActionsViewController>();
if (controller != null) {
    PopupWindowShowAction postponeAction = controller.Actions["Task.Postpone.PostponeParametersObject"] as PopupWindowShowAction;
    // ...
}

VB.NET

Imports DevExpress.ExpressApp.SystemModule
Imports DevExpress.ExpressApp.Actions
' ...
Dim controller As ObjectMethodActionsViewController = Frame.GetController(Of ObjectMethodActionsViewController)()
If controller IsNot Nothing Then
    Dim postponeAction As PopupWindowShowAction = TryCast(controller.Actions("Task.Postpone.PostponeParametersObject"), PopupWindowShowAction)
    ' ...
End If

Help Topics that List Built-in Controllers and their Actions

You can search through the Built-in Controllers and Actions section of this documentation to find the required Action and its Controller.

Note

You can also search an Action by its identifier or caption in XAF sources which are installed to %PROGRAMFILES%\DevExpress 23.2\Components\Sources\ by default.