How to: Disable an Action When the Current View Has Unsaved Changes

• Jun 11, 2021
• 2 minutes to read

This topic demonstrates how to disable an Action when business objects loaded to the current Object Space are changed. For this purpose, the IObjectSpace.ModifiedChanged event is handled, and the ActionBase.Enabled property is set based on the IObjectSpace.IsModified property.

C#

using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Actions;
using System;
// ...
public class ViewController1 : ViewController {
    SimpleAction action1;
    public ViewController1() {
        action1 = new SimpleAction(this, "Action1", DevExpress.Persistent.Base.PredefinedCategory.View);
    }
    protected override void OnActivated() {
        base.OnActivated();
        ObjectSpace.ModifiedChanged += ObjectSpace_ModifiedChanged;
        UpdateActionState();
    }
    void ObjectSpace_ModifiedChanged(object sender, EventArgs e) {
        UpdateActionState();
    }
    protected virtual void UpdateActionState() {
        action1.Enabled["ObjectSpaceIsModified"] = !ObjectSpace.IsModified;
    }
    protected override void OnDeactivated() {
        base.OnDeactivated();
        ObjectSpace.ModifiedChanged -= ObjectSpace_ModifiedChanged;
    }
}

VB.NET

Imports DevExpress.ExpressApp
Imports DevExpress.ExpressApp.Actions
Imports System
' ...
Public Class ViewController1
    Inherits ViewController

    Private action1 As SimpleAction
    Public Sub New()
        action1 = New SimpleAction(Me, "Action1", DevExpress.Persistent.Base.PredefinedCategory.View)
    End Sub
    Protected Overrides Sub OnActivated()
        MyBase.OnActivated()
        AddHandler ObjectSpace.ModifiedChanged, AddressOf ObjectSpace_ModifiedChanged
        UpdateActionState()
    End Sub
    Private Sub ObjectSpace_ModifiedChanged(ByVal sender As Object, ByVal e As EventArgs)
        UpdateActionState()
    End Sub
    Protected Overridable Sub UpdateActionState()
        action1.Enabled("ObjectSpaceIsModified") = Not ObjectSpace.IsModified
    End Sub
    Protected Overrides Sub OnDeactivated()
        MyBase.OnDeactivated()
        RemoveHandler ObjectSpace.ModifiedChanged, AddressOf ObjectSpace_ModifiedChanged
    End Sub
End Class

As a result, the Action1 is grayed out in the UI when there are unsaved changes in the current View. It is impossible to execute the Action until changes are saved to a data store (e.g., using the Save Action). When the changes are saved, the Action1 reverts to its normal state.