IObjectSpace.Committing Event

Occurs before persistent objects are saved to the database.

Namespace: DevExpress.ExpressApp

Assembly: DevExpress.ExpressApp.v24.1.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

event EventHandler<CancelEventArgs> Committing

VB.NET

Event Committing As EventHandler(Of CancelEventArgs)

Event Data

The Committing event's data class is CancelEventArgs. The following properties provide information specific to this event:

Property	Description
Cancel	Gets or sets a value indicating whether the event should be canceled.

Remarks

The IObjectSpace.CommitChanges method call raises the Committing event before the changes are stored in the database. In the Committing event handler, set the CancelEventArgs.Cancel parameter to true to prevent the commit. This parameter’s default value is false.

In the BaseObjectSpace descendant, the BaseObjectSpace.CommitChanges method invokes the BaseObjectSpace.DoCommit method and raises the Committing event. Override the BaseObjectSpace.DoCommit method to implement your logic to persist changes.

The following example prevents commits in the Payment Detail View:

C#

using System.ComponentModel;
using DevExpress.ExpressApp;

// ...
public class CancelCommitController : ObjectViewController<DetailView, MainDemo.Module.BusinessObjects.Payment> {
    protected override void OnActivated() {
        base.OnActivated();
        View.ObjectSpace.Committing += ObjectSpace_Committing;
    }
    private void ObjectSpace_Committing(object sender, CancelEventArgs e) {
        e.Cancel = true;
    }
    protected override void OnDeactivated() {
        View.ObjectSpace.Committing -= ObjectSpace_Committing;
    }
}

VB.NET

Imports System.ComponentModel
Imports DevExpress.ExpressApp

Public Class CancelCommitController
    Inherits ObjectViewController(Of DetailView, MainDemo.Module.BusinessObjects.Payment)

    Protected Overrides Sub OnActivated()
        MyBase.OnActivated()
        AddHandler View.ObjectSpace.Committing, AddressOf ObjectSpace_Committing
    End Sub
    Private Sub ObjectSpace_Committing(ByVal sender As Object, ByVal e As CancelEventArgs)
        e.Cancel = True
    End Sub
    Protected Overrides Sub OnDeactivated()
        RemoveHandler View.ObjectSpace.Committing, AddressOf ObjectSpace_Committing
    End Sub
End Class

The following code shows how to manually save child collection changes made in the parent Detail View:

C#

using DevExpress.ExpressApp;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using YourSolutionName.Module.BusinessObjects;

namespace YourSolutionName.Module.Controllers {
    public class MyViewController : ObjectViewController<DetailView, Parent> {
        List<Child> detailObjectsCache = new List<Child>();
        protected override void OnActivated() {
            base.OnActivated();
            ObjectSpace.CustomCommitChanges += ObjectSpace_CustomCommitChanges;
            ObjectSpace.Committing += ObjectSpace_Committing;
            ObjectSpace.Committed += ObjectSpace_Committed;
            ObjectSpace.Reloaded += ObjectSpace_Reloaded;
        }
        protected override void OnDeactivated() {
            ObjectSpace.CustomCommitChanges -= ObjectSpace_CustomCommitChanges;
            ObjectSpace.Committing -= ObjectSpace_Committing;
            ObjectSpace.Committed -= ObjectSpace_Committed;
            ObjectSpace.Reloaded -= ObjectSpace_Reloaded;
            base.OnDeactivated();
        }
        void ObjectSpace_Reloaded(object sender, EventArgs e) {
            detailObjectsCache.Clear();
        }
        void ObjectSpace_Committed(object sender, EventArgs e) {
            detailObjectsCache.Clear();
        }
        void ObjectSpace_Committing(object sender, CancelEventArgs e) {
            IObjectSpace os = (IObjectSpace)sender;
            for (int i = os.ModifiedObjects.Count - 1; i >= 0; i--) {
                object item = os.ModifiedObjects[i];
                if (typeof(Child).IsAssignableFrom(item.GetType())) {
                    detailObjectsCache.Add(item as Child);
                    os.RemoveFromModifiedObjects(item);
                }
            }
        }
        void ObjectSpace_CustomCommitChanges(object sender, HandledEventArgs e) {
            // Implement custom logic to save Detail objects here. 
            foreach (Child detailObject in detailObjectsCache) {
                //...  
            }
        }
    }
}

VB.NET

Imports DevExpress.ExpressApp
Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports YourSolutionName.Module.BusinessObjects

Namespace YourSolutionName.Module.Controllers
    Public Class MyViewController
        Inherits ObjectViewController(Of DetailView, Parent)

        Private detailObjectsCache As List(Of Child) = New List(Of Child)()

        Protected Overrides Sub OnActivated()
            MyBase.OnActivated()
            AddHandler ObjectSpace.CustomCommitChanges, AddressOf ObjectSpace_CustomCommitChanges
            AddHandler ObjectSpace.Committing, AddressOf ObjectSpace_Committing
            AddHandler ObjectSpace.Committed, AddressOf ObjectSpace_Committed
            AddHandler ObjectSpace.Reloaded, AddressOf ObjectSpace_Reloaded
        End Sub

        Protected Overrides Sub OnDeactivated()
            RemoveHandler ObjectSpace.CustomCommitChanges, AddressOf ObjectSpace_CustomCommitChanges
            RemoveHandler ObjectSpace.Committing, AddressOf ObjectSpace_Committing
            RemoveHandler ObjectSpace.Committed, AddressOf ObjectSpace_Committed
            RemoveHandler ObjectSpace.Reloaded, AddressOf ObjectSpace_Reloaded
            MyBase.OnDeactivated()
        End Sub

        Private Sub ObjectSpace_Reloaded(ByVal sender As Object, ByVal e As EventArgs)
            detailObjectsCache.Clear()
        End Sub

        Private Sub ObjectSpace_Committed(ByVal sender As Object, ByVal e As EventArgs)
            detailObjectsCache.Clear()
        End Sub

        Private Sub ObjectSpace_Committing(ByVal sender As Object, ByVal e As CancelEventArgs)
            Dim os As IObjectSpace = CType(sender, IObjectSpace)

            For i As Integer = os.ModifiedObjects.Count - 1 To 0
                Dim item As Object = os.ModifiedObjects(i)

                If GetType(Child).IsAssignableFrom(item.[GetType]()) Then
                    detailObjectsCache.Add(TryCast(item, Child))
                    os.RemoveFromModifiedObjects(item)
                End If
            Next
        End Sub

        Private Sub ObjectSpace_CustomCommitChanges(ByVal sender As Object, ByVal e As HandledEventArgs)
            ' Implement custom logic to save Detail objects here.  
            For Each detailObject As Child In detailObjectsCache
            Next
        End Sub
    End Class
End Namespace

For another example, see the GetObjectsToDelete(Boolean) method description.