Add an Action with Option Selection
- 4 minutes to read
This lesson explains how to create an Action that supports option selection.
In this lesson, you will implement a new View Controller with a SingleChoiceAction
. This action will allow users to select values for the Task.Priority
and Task.Status
properties.
Note
Before you proceed, take a moment to review the previous lessons:
#Step-by-Step Instructions
- Add a new View Controller to the MySolution.Module project. Name it TaskActionsController.
In the TaskActionsController.cs file, set the controller’s
TargetObjectType
:C#using DevExpress.ExpressApp; using MySolution.Module.BusinessObjects; // ... public partial class TaskActionsController : ViewController { public TaskActionsController() { InitializeComponent(); TargetObjectType = typeof(DemoTask); } // ... }
Add a
SingleChoiceAction
and specify its properties:C#public partial class TaskActionsController : ViewController { public TaskActionsController() { InitializeComponent(); TargetObjectType = typeof(DemoTask); SingleChoiceAction SetTaskAction = new SingleChoiceAction(this, "SetTaskAction", PredefinedCategory.Edit) { Caption = "Set Task", //Specify the display mode for the Action's items. Here the items are operations that you perform against selected records. ItemType = SingleChoiceActionItemType.ItemIsOperation, //Set the Action to become available in the Task List View when a user selects one or more objects. SelectionDependencyType = SelectionDependencyType.RequireMultipleObjects }; } // ... }
To populate the Action with items, fill the Action’s ChoiceActionBase.Items collection in the Controller’s constructor:
C#public partial class TaskActionsController : ViewController { private ChoiceActionItem setPriorityItem; private ChoiceActionItem setStatusItem; public TaskActionsController() { // ... setPriorityItem = new ChoiceActionItem(CaptionHelper.GetMemberCaption(typeof(DemoTask), "Priority"), null); SetTaskAction.Items.Add(setPriorityItem); FillItemWithEnumValues(setPriorityItem, typeof(Priority)); setStatusItem = new ChoiceActionItem(CaptionHelper.GetMemberCaption(typeof(DemoTask), "Status"), null); SetTaskAction.Items.Add(setStatusItem); FillItemWithEnumValues(setStatusItem, typeof(BusinessObjects.TaskStatus)); } private void FillItemWithEnumValues(ChoiceActionItem parentItem, Type enumType) { EnumDescriptor ed = new EnumDescriptor(enumType); foreach(object current in ed.Values) { ChoiceActionItem item = new ChoiceActionItem(ed.GetCaption(current), current); item.ImageName = ImageLoader.Instance.GetEnumValueImageName(current); parentItem.Items.Add(item); } } }
The code sample above organizes items from the Action’s
Items
collection as a tree:- The root level contains items whose captions correspond to the
DemoTask.Priority
andDemoTask.Status
property names. The CaptionHelper object returns item captions. - The nested level contains the
Priority
andStatus
enumeration values. The EnumDescriptor object returns item captions.
- ASP.NET Core Blazor
- Windows Forms
When you populate the ChoiceActionBase.Items collection in a Controller constructor as shown in the code above, you can use the Model Editor‘s ActionDesign | Actions | <Action> | ChoiceActionItems node to set an image name, a shortcut, and a localized caption for the added items.
If you populate the
Items
collection in a Controller.Activated event handler, the Model Editor does not load items.- The root level contains items whose captions correspond to the
Open the DemoTask.cs file and assign images to the
Priority
enumeration value as in the code sample below:C#public enum Priority { [ImageName("State_Priority_Low")] Low, [ImageName("State_Priority_Normal")] Normal, [ImageName("State_Priority_High")] High }
In this tutorial, the enumeration values have the ImageNameAttribute attributes to set images for these values in the UI.
XAF ships with the standard image library. The library includes the
State_Priority_Low
,State_Priority_Normal
andState_Priority_High
images used in this lesson.Handle the SingleChoiceAction.Execute event that occurs when a user chooses the Action’s item:
C#//... using System.Collections; public partial class TaskActionsController : ViewController { // ... public TaskActionsController() { // ... SetTaskAction.Execute += SetTaskAction_Execute; } private void SetTaskAction_Execute(object sender, SingleChoiceActionExecuteEventArgs e) { /*Create a new ObjectSpace if the Action is used in List View. Use this ObjectSpace to manipulate the View's selected objects.*/ IObjectSpace objectSpace = View is ListView ? Application.CreateObjectSpace(typeof(DemoTask)) : View.ObjectSpace; ArrayList objectsToProcess = new ArrayList(e.SelectedObjects); if(e.SelectedChoiceActionItem.ParentItem == setPriorityItem) { foreach(Object obj in objectsToProcess) { DemoTask objInNewObjectSpace = (DemoTask)objectSpace.GetObject(obj); objInNewObjectSpace.Priority = (Priority)e.SelectedChoiceActionItem.Data; } } else if(e.SelectedChoiceActionItem.ParentItem == setStatusItem) { foreach(Object obj in objectsToProcess) { DemoTask objInNewObjectSpace = (DemoTask)objectSpace.GetObject(obj); objInNewObjectSpace.Status = (BusinessObjects.TaskStatus)e.SelectedChoiceActionItem.Data; } } objectSpace.CommitChanges(); View.ObjectSpace.Refresh(); } }
To access a selected action item, use the event handler’s e.SelectedChoiceActionItem parameter.
Create a separate
ObjectSpace
to edit multiple objects that are currently displayed. This technique improves performance, as each object change does not trigger the grid control’s events.Run the application. Select the Task item in the navigation control. After that, the Set Task Action becomes active.
To change the
Priority
orStatus
property of the selectedTask
object, select an item in the Action’s drop-down list:- ASP.NET Core Blazor
- Windows Forms
Note
Code
#Next Lesson
Add a Simple Action Using an Attribute