Add a Simple Action (.NET 6)

• Nov 17, 2022
• 4 minutes to read

This lesson explains how to create a Simple Action.

A Simple Action is a button that executes custom code when a user clicks it.

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

Note

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

• Inherit from the Business Class Library Class (XPO/EF core)
• Implement Custom Business Classes and Reference Properties (XPO/EF core)
• Set a Many-to-Many Relationship (XPO/EF core)

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 DevExpress.ExpressApp;
   
   //...
   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(Contact);
       }
   // ...
   

   If you do not specify the TargetObjectType property, the application displays the controller’s actions for each detail form.

   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 controller 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:

   C# (XPO)

   using DevExpress.ExpressApp;
   using DevExpress.ExpressApp.Actions;
   using DevExpress.Persistent.Base;
   using MySolution.Module.BusinessObjects;
    //...
   public partial class ClearContactTasksController : ViewController {
       public ClearContactTasksController() {
           InitializeComponent();
           TargetViewType = ViewType.DetailView;
           TargetObjectType = typeof(Contact);
   
           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.
           clearTasksAction.Execute += ClearTasksAction_Execute;
       }
       private void ClearTasksAction_Execute(Object sender, SimpleActionExecuteEventArgs e) {
           while(((Contact)View.CurrentObject).Tasks.Count > 0) {
               ((Contact)View.CurrentObject).Tasks.Remove(((Contact)View.CurrentObject).Tasks[0]);
               ObjectSpace.SetModified(View.CurrentObject);
           }
       }
   // ...
   

   C# (EF Core)

   using DevExpress.ExpressApp;
   using DevExpress.ExpressApp.Actions;
   using DevExpress.Persistent.Base;
   using MySolution.Module.BusinessObjects;
    //...
   public partial class ClearContactTasksController : ViewController {
       public ClearContactTasksController() {
           InitializeComponent();
           TargetViewType = ViewType.DetailView;
           TargetObjectType = typeof(Contact);
   
           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.
           clearTasksAction.Execute += ClearTasksAction_Execute;
       }
       private void ClearTasksAction_Execute(Object sender, SimpleActionExecuteEventArgs e) {
           while(((Contact)View.CurrentObject).Tasks.Count > 0) {
               ((Contact)View.CurrentObject).Tasks.Remove(((Contact)View.CurrentObject).Tasks[0]);
               ObjectSpace.SetModified(View.CurrentObject, View.ObjectTypeInfo.FindMember(nameof(Contact.Tasks)));
           }
       }
   // ...
   

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

   The main entry point of a Simple Action is its Execute event. Handle this event to execute custom code.

4. Run the application.

   Open a detail form for a Contact 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 Contact.

   

   Tip

   You can display an action’s button in a Detail View layout instead of a toolbar: How to: Include an Action in a Detail View Layout.

Next Lesson

Add a Parameterized Action