Add a Simple Action

• Feb 16, 2023
• 3 minutes to read

This lesson explains how to create a Simple Action — a button that executes custom code when a user clicks it.

The instructions below demonstrate how to add the Clear tasks button to the Employee Detail View. A click on this button clears all Tracked Tasks of the selected Employee.

Note

Before you proceed, take a moment to review the previous lessons:

• Implement a Data Model: Basics
• Implement Reference Properties
• Configure a Many-to-Many Relationship

Step-by-Step Instructions

1. Add a View Controller. In the Solution Explorer, right-click the Controllers folder in the MySolution.Module project and choose Add DevExpress Item | New Item… to invoke the Template Gallery. Select the XAF Controllers | View Controller Visual Studio template, specify ClearContactTasksController as the new item’s name, and click Add Item.

   

2. Visual Studio displays an autogenerated ClearContactTasksController.cs file with a single View Controller declaration. In the controller constructor, specify the controller properties:

   // ...
   using MySolution.Module.BusinessObjects;
   
   // ...
   public partial class ClearContactTasksController : ViewController {
       public ClearContactTasksController() {
           InitializeComponent();
           //Activate the Controller only in the Detail View
           TargetViewType = ViewType.DetailView;
           //Specify the type of objects that can use the Controller
           TargetObjectType = typeof(Employee);
       }
   // ...
   }
   

   If you do not specify the TargetObjectType property, the application displays the controller’s actions for all Detail Views.

   Tip

   You can also create a generic ViewController<ViewType> or ObjectViewController<ViewType, ObjectType> object and specify the target type as the ViewType parameter. For more information on how to customize a controller’s functionality, refer to the following topic: Define the Scope of Controllers and Actions.

3. Add a new action to the controller and a handler for the action’s Execute event:

   using DevExpress.ExpressApp;
   using DevExpress.ExpressApp.Actions;
   using DevExpress.Persistent.Base;
   using MySolution.Module.BusinessObjects;
   // ...
   public partial class ClearEmployeeTasksController : ViewController {
       public ClearEmployeeTasksController() {
           InitializeComponent();
           TargetViewType = ViewType.DetailView;
           TargetObjectType = typeof(Employee);
   
           SimpleAction clearTasksAction = new SimpleAction(this, "ClearTaskAction", PredefinedCategory.View) {
               //Specify the Action's button caption.
               Caption = "Clear tasks",
               //Specify the confirmation message that pops up when a user executes an Action.
               ConfirmationMessage = "Are you sure you want to clear the Tasks list?",
               //Specify the icon of the Action's button in the interface.
               ImageName = "Action_Clear"
           };
           //This event fires when a user clicks the Simple Action control. Handle this event to execute custom code.
           clearTasksAction.Execute += ClearTasksAction_Execute;
       }
       private void ClearTasksAction_Execute(Object sender, SimpleActionExecuteEventArgs e) {
           while(((Employee)View.CurrentObject).DemoTasks.Count > 0) {
               ((Employee)View.CurrentObject).DemoTasks.Remove(((Employee)View.CurrentObject).DemoTasks[0]);
               ObjectSpace.SetModified(View.CurrentObject, View.ObjectTypeInfo.FindMember(nameof(Employee.DemoTasks)));
           }
       }
   // ...
   }
   

   You can use one of the standard images or import your own to customize the Action button’s icon.

4. Run the application.

   Open a Detail View for an Employee item. Link several tasks to this item and save it.

   Click the Clear tasks button. A confirmation message appears. Click OK to remove all Tasks from the current Employee.

   ASP.NET Core Blazor

   

   Windows Forms

   

You can display an action’s button in a Detail View layout instead of a toolbar. Refer to the following topic for more information: How to: Include an Action in a Detail View Layout.

Note

CodeRush allows you to add Actions and Controllers with a few keystrokes. To learn about the Code Templates for XAF, refer to the following help topic: XAF Templates.

Next Lesson

Add a Parametrized Action