IObjectSpace.ModifiedChanged Event

Occurs when the current Object Space’s IObjectSpace.IsModified state is changed.

Namespace: DevExpress.ExpressApp

Assembly: DevExpress.ExpressApp.v23.2.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

event EventHandler ModifiedChanged

VB.NET

Event ModifiedChanged As EventHandler

Event Data

The ModifiedChanged event's data class is EventArgs.

Remarks

In the BaseObjectSpace descendant, you don’t have to raise the ModifiedChanged event. It is raised in the protected BaseObjectSpace.SetIsModified method after the BaseObjectSpace.IsModified property has changed.

Handle this event to execute custom code when the Object Space’s Modified state is changed. However, it is already handled internally to change Actions states in dependence of the IObjectSpace.IsModified property value.

The following code disables an Action when business objects in the current Object Space are changed.

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