Customize the Data Storing Mechanism

• Feb 09, 2024
• 3 minutes to read

The Audit Trail Module stores audit records (AuditDataItem objects) in an application database. The SaveAuditTrailData event allows you to configure how this Module saves information. This event is raised when the Module commits an AuditDataItem object to the database. In this event handler, you can modify the SaveAuditTrailDataContext.AuditTrailDataItems (in .NET 6+ applications) or SaveAuditTrailDataEventArgs.AuditTrailDataItems (in .NET Framework applications) collection, and add new or remove unnecessary items. The following code demonstrates how to remove ObjectCreated records.

In .NET 6+ Applications

File: MySolution.Blazor.Server\Startup.cs, MySolution.Win\Startup.cs, MySolution.WebApi\Startup.cs

C#

using DevExpress.Persistent.AuditTrail;
// ...
builder.Modules
    .AddAuditTrailXpo(o => {
        o.Events.OnCustomizeAuditOperationTypeFilter = context => {
            if (context.AuditOperationType == AuditOperationType.ObjectChanged ||
                context.AuditOperationType == AuditOperationType.ObjectCreated) {
                context.SaveAuditOperation = false;
            }
        };
    })

In .NET Framework Applications

File: MySolution.Win\Program.cs, MySolution.Web\Global.asax.cs

C# (WinForms)

using DevExpress.Persistent.AuditTrail;
// ...
static class Program {
    // ...
    static void Main() {
        MySolutionWindowsFormsApplication application = new MySolutionWindowsFormsApplication();
        // ...
        AuditTrailService.Instance.SaveAuditTrailData += 
            new SaveAuditTrailDataEventHandler(Instance_SaveAuditTrailData);
        application.Setup();
        application.Start();
        // ...
    }
    static void Instance_SaveAuditTrailData(object sender, SaveAuditTrailDataEventArgs e) {
        for(int i = e.AuditTrailDataItems.Count - 1; i >= 0; i--) {
            var item = e.AuditTrailDataItems[i];
            if(item.OperationType == AuditOperationType.ObjectCreated) {
                e.AuditTrailDataItems.RemoveAt(i);
            }
        }
    }
}

C# (ASP.NET Web Forms)

using DevExpress.Persistent.AuditTrail;
// ...
public class Global : System.Web.HttpApplication {
    // ...
    protected void Session_Start(object sender, EventArgs e) {
        WebApplication.SetInstance(Session, new MySolutionWebApplication());
        AuditTrailService.Instance.SaveAuditTrailData += 
            new SaveAuditTrailDataEventHandler(Instance_SaveAuditTrailData);
        // ...
        WebApplication.Instance.Setup();
        WebApplication.Instance.Start();
    }
    static void Instance_SaveAuditTrailData(object sender, SaveAuditTrailDataEventArgs e) {
        for(int i = e.AuditTrailDataItems.Count - 1; i >= 0; i--) {
            var item = e.AuditTrailDataItems[i];
            if(item.OperationType == AuditOperationType.ObjectCreated) {
                e.AuditTrailDataItems.RemoveAt(i);
            }
        }
    }
}

Replace the Default Data Storing Mechanism with a Custom Mechanism

To do this, set the event’s SaveAuditTrailDataContext.Handled (in .NET 6+ applications) or SaveAuditTrailDataEventArgs.Handled (in .NET Framework applications) argument to true in the SaveAuditTrailData event handler.

In .NET 6+ Applications

File: MySolution.Blazor.Server\Startup.cs, MySolution.Win\Startup.cs, MySolution.WebApi\Startup.cs

C#

using DevExpress.Persistent.AuditTrail;
// ...
builder.Modules
    .AddAuditTrailXpo(o => {
        o.Events.OnCustomizeAuditOperationTypeFilter = context => {
            // Save the data passed as the `context.AuditTrailDataItems` parameter
            context.Handled = true; // Disable the default data storing mechanism
        };
    })

In .NET Framework Applications

File: MySolution.Win\Program.cs, MySolution.Web\Global.asax.cs

C# (WinForms)

using DevExpress.Persistent.AuditTrail;
// ...
static class Program {
    // ...
    static void Main() {
        MySolutionWindowsFormsApplication application = new MySolutionWindowsFormsApplication();
        // ...
        AuditTrailService.Instance.SaveAuditTrailData += 
            new SaveAuditTrailDataEventHandler(Instance_SaveAuditTrailData);
        application.Setup();
        application.Start();
        // ...
    }
    static void Instance_SaveAuditTrailData(object sender, SaveAuditTrailDataEventArgs e) {
        // Save the data passed as the `e.AuditTrailDataItems` parameter
        e.Handled = true; // Disable the default data storing mechanism
    }
}

C# (ASP.NET Web Forms)

using DevExpress.Persistent.AuditTrail;
// ...
public class Global : System.Web.HttpApplication {
    // ...
    protected void Session_Start(object sender, EventArgs e) {
        WebApplication.SetInstance(Session, new MySolutionWebApplication());
        AuditTrailService.Instance.SaveAuditTrailData += 
            new SaveAuditTrailDataEventHandler(Instance_SaveAuditTrailData);
        // ...
        WebApplication.Instance.Setup();
        WebApplication.Instance.Start();
    }
    static void Instance_SaveAuditTrailData(object sender, SaveAuditTrailDataEventArgs e) {
        // Save the data passed as the `e.AuditTrailDataItems` parameter
        e.Handled = true; // Disable the default data storing mechanism
    }
}

Alternative Techniques

• If you do not want to log specific operations, implement the technique described in the Audit Specific Operations topic.
• You can create the AuditDataStore descendant and override its Save method. Register this custom data store within the Audit Trail system as described in the following topic: Miscellaneous Customizations of the Audit Trail System (XPO).