PersistentBase.OnSaving() Method

Invoked when the current object is about to be saved.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v20.2.dll

NuGet Package: DevExpress.Xpo

NuGet Packages: DevExpress.WindowsDesktop.Xpo, DevExpress.Xpo

Declaration

C#

protected virtual void OnSaving()

VB.NET

Protected Overridable Sub OnSaving

Remarks

Override this method in your PersistentBase descendants to add custom logic to a persistent object when the object is about to be saved.

Example

The example below demonstrated how to automatically populate the CreatedBy, CreatedOn, UpdatedBy, and UpdatedOn properties (audit columns) in a business class.

C#

using DevExpress.Xpo;  
...

namespace YourSolutionName.BusinessObjects {  
    [DefaultClassOptions]  
    public class Contact : BaseObject {  
        public Contact(Session session)  
            : base(session) {  
        }  
        // Get a current active user
        User GetCurrentUser() {  
            return Session.GetObjectByKey<User>(SecuritySystem.CurrentUserId);  
        }  
        // Automatically fill the CreatedOn and CreatedBy columns 
        // when a current user creates a new Contact item.
        public override void AfterConstruction() {  
            base.AfterConstruction();  
            CreatedOn = DateTime.Now;  
            CreatedBy = GetCurrentUser();  
        }  
        // Automatically fill the UpdatedOn and UpdatedBy columns 
        // when a current user saves a modified Contact item.
        protected override void OnSaving() {  
            base.OnSaving();  
            UpdatedOn = DateTime.Now;  
            UpdatedBy = GetCurrentUser();  
        }

        protected override void OnChanged(string propertyName, object oldValue, object newValue) {
            base.OnChanged(propertyName, oldValue, newValue);
            if(!IsLoading) {
                switch(propertyName) {
                    // Run custom code when the "Email" property value is changed.
                    case nameof(Email):
                        UpdateContacts();
                        break;
                }
            }
        }

        User createdBy;  
        public User CreatedBy {  
            get { return createdBy; }  
            set { SetPropertyValue("CreatedBy", ref createdBy, value); }  
        }  
        DateTime createdOn;  
        public DateTime CreatedOn {  
            get { return createdOn; }  
            set { SetPropertyValue("CreatedOn", ref createdOn, value); }  
        }  
        User updatedBy;  
        public User UpdatedBy {  
            get { return updatedBy; }  
            set { SetPropertyValue("UpdatedBy", ref updatedBy, value); }  
        }  
        DateTime updatedOn;  
        public DateTime UpdatedOn {  
            get { return updatedOn; }  
            set { SetPropertyValue("UpdatedOn", ref updatedOn, value); }  
        }  
    }  
}  

VB.NET

Imports DevExpress.Xpo
...

Namespace YourSolutionName.BusinessObjects
    <DefaultClassOptions>
    Public Class Contact
        Inherits BaseObject

        Public Sub New(ByVal session As Session)
            MyBase.New(session)
        End Sub

        ' Get a current active user
        Private Function GetCurrentUser() As User
            Return Session.GetObjectByKey(Of User)(SecuritySystem.CurrentUserId)
        End Function

        ' Automatically fill the CreatedOn and CreatedBy columns 
        ' when a current user creates a new Contact item.
        Public Overrides Sub AfterConstruction()
            MyBase.AfterConstruction()
            CreatedOn = Date.Now
            CreatedBy = GetCurrentUser()
        End Sub

        ' Automatically fill the UpdatedOn and UpdatedBy columns 
        ' when a current user saves a modified Contact item.
        Protected Overrides Sub OnSaving()
            MyBase.OnSaving()
            UpdatedOn = Date.Now
            UpdatedBy = GetCurrentUser()
        End Sub

        Protected Overrides Sub OnChanged(ByVal propertyName As String, ByVal oldValue As Object, ByVal newValue As Object)
            MyBase.OnChanged(propertyName, oldValue, newValue)

            If Not IsLoading Then
                Select Case propertyName
                    ' Run custom code when the "Email" property value is changed.
                    Case NameOf(Email)
                        UpdateContacts()
                End Select
            End If
        End Sub

        Private createdByField As User

        Public Property CreatedBy As User
            Get
                Return createdByField
            End Get
            Set(ByVal value As User)
                SetPropertyValue("CreatedBy", createdByField, value)
            End Set
        End Property

        Private createdOnField As Date

        Public Property CreatedOn As Date
            Get
                Return createdOnField
            End Get
            Set(ByVal value As Date)
                SetPropertyValue("CreatedOn", createdOnField, value)
            End Set
        End Property

        Private updatedByField As User

        Public Property UpdatedBy As User
            Get
                Return updatedByField
            End Get
            Set(ByVal value As User)
                SetPropertyValue("UpdatedBy", updatedByField, value)
            End Set
        End Property

        Private updatedOnField As Date

        Public Property UpdatedOn As Date
            Get
                Return updatedOnField
            End Get
            Set(ByVal value As Date)
                SetPropertyValue("UpdatedOn", updatedOnField, value)
            End Set
        End Property
    End Class
End Namespace

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the OnSaving() method.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

XPO_how-to-track-changes-made-to-persistent-objects-and-write-them-into-a-separate-table-e2419/CS/Q149895/Northwind.cs#L29

protected override void OnSaving() {
    base.OnSaving();
    if(Session.IsNewObject(this)) UpdateAudit(Action.Insert);

VB.NET

XPO_how-to-track-changes-made-to-persistent-objects-and-write-them-into-a-separate-table-e2419/VB/Q149895/Northwind.vb#L33

Protected Overrides Sub OnSaving()
    MyBase.OnSaving()
    If Session.IsNewObject(Me) Then