How do I set the Action's confirmation message dynamically based on object property values before this action gets executed?

Hello,

The idea is to implement a custom ViewController to access a required Action as per Customize Controllers and Actions  and modify its ConfirmationMessage property in code on required events (e.g. Controller.Activated, View.ControlsCreated, View.CurrentObjectChanged,  CRUD events of IObjectSpace or even the 'Changed' event of the current persistent object) based on the current object value.
I have modified your code as follows:

C#
using DevExpress.ExpressApp;  
using DevExpress.ExpressApp.SystemModule;  
using Solution1.Module.BusinessObjects;  

namespace YourSolutionName.Module.Controllers {  
    public class UpdateConfirmationMessageForProjectDetailViewController : ObjectViewController<DetailView, Project> {  
        private ModificationsController controller;  
        protected override void OnActivated() {  
            base.OnActivated();  
            // Perform various tasks depending on the target View.  
            controller = Frame.GetController<ModificationsController>();  
            SetConfirmationMessage(ViewCurrentObject);  
            View.ObjectSpace.ObjectChanged += ObjectSpace_ObjectChanged;  
        }  
        void ObjectSpace_ObjectChanged(object sender, ObjectChangedEventArgs e) {  
            if (e.Object is Project) {  
                SetConfirmationMessage((Project)e.Object);  
            }  
        }  
        protected override void OnDeactivated() {  
            // Unsubscribe from previously subscribed events and release other references and resources.  
            View.ObjectSpace.ObjectChanged -= ObjectSpace_ObjectChanged;  
            base.OnDeactivated();  
        }  
        private void SetConfirmationMessage(Project theProject) {  
            bool yourBusinessCondition = theProject != null && !theProject.State;  
            string message = yourBusinessCondition ? string.Format("{0} project state is false. Do you want to start this project?", theProject.Name) : null;  
            if (controller != null) {  
                controller.SaveAndCloseAction.ConfirmationMessage = message;  
                controller.SaveAction.ConfirmationMessage = message;  
                controller.SaveAndNewAction.ConfirmationMessage = message;  
            }  
        }  

    }  
}  

Another example is available in the end of the How to: Access Objects Selected in the Current View help topic, where the DeleteObjectsViewController.DeleteAction's confirmation message is updated based on the Full Name of the Contact that is going to be deleted.

Please let me know if this solution meets your needs. I wanted to emphasize that handling the ObjectChanged event in this manner should not cause any problems.

Important notes:

1. Decorate your dependent business class property with the ImmediatePostDataattribute to be notified of object changes immediately.
2. In WinForms to display a confirmation message after executing a custom operation in code of your Controller, use the XafApplication.AskConfirmation or WinApplication.GetUserChoice method. To get an application's instance in the Controller, use its Application property.
3. At the moment XAF doesn't allow you to set unique confirmation message for each ChoiceActionItem of SingleChoiceAction.