Audit Trail Module (EF Core)

• Nov 02, 2023
• 5 minutes to read

This topic describes how to add the Audit Trail Module to your ASP.NET Core Blazor or WinForms application and explains the Module’s features specific to the Entity Framework Core ORM.

Audited Objects

The Audit Trail Module logs changes in the following objects and properties:

• Persistent classes registered as DbSet<TEntity> properties in DbContext.
• Public writable simple and reference properties defined in persistent classes. The Module does not log changes in read-only properties (properties without the set accessor).
• Public collection properties defined in persistent classes.

Add the Audit Trail Module to Your Application

Follow the steps below to add the Audit Trail Module to your application. If you added this Module when you created an XAF application, the Solution Wizard generates the described code automatically:

1. Add the DevExpress.ExpressApp.AuditTrail.EFCore NuGet package to the application’s main module (MySolution.Module).

2. Add a new DbContext used to store audit trail records to the application’s main module and register the AuditDataItemPersistent and AuditEFCoreWeakReference types both in this DbContext and in the application’s main DbContext.

   Note

   You only need to declare the properties used by the Audit Trail Module in both DbContexts if they share the same database connection, which is the default configuration that XAF Solution Wizard generates. If you store audit trail records in a separate database, you should only declare these properties in the additional DbContext. Refer to the following help topic for more information on this technique: Store Audit Data in a Separate Database.

   File: MySolution.Module/BusinessObjects/MySolutionDbContext.cs

   C#

   public class MySolutionEFCoreDbContext : DbContext {
       // ...
       // Do not add these properties to the main DbConext if you store 
       // audit trail records in a separate database
       public DbSet<AuditDataItemPersistent> AuditData { get; set; }
       public DbSet<AuditEFCoreWeakReference> AuditEFCoreWeakReference { get; set; }
   
       protected override void OnModelCreating(ModelBuilder modelBuilder) {
           base.OnModelCreating(modelBuilder);
           // ...
           modelBuilder.Entity<AuditEFCoreWeakReference>()
               .HasMany(p => p.AuditItems)
               .WithOne(p => p.AuditedObject);
           modelBuilder.Entity<AuditEFCoreWeakReference>()
               .HasMany(p => p.OldItems)
               .WithOne(p => p.OldObject);
           modelBuilder.Entity<AuditEFCoreWeakReference>()
               .HasMany(p => p.NewItems)
               .WithOne(p => p.NewObject);
           modelBuilder.Entity<AuditEFCoreWeakReference>()
               .HasMany(p => p.UserItems)
               .WithOne(p => p.UserObject);
           modelBuilder.Entity<ModelDifference>()
               .HasMany(t => t.Aspects)
               .WithOne(t => t.Owner)
               .OnDelete(DeleteBehavior.Cascade);
       }
   }
   public class MySolutionAuditingDbContext : DbContext {
       public DbSet<AuditDataItemPersistent> AuditData { get; set; }
       public DbSet<AuditEFCoreWeakReference> AuditEFCoreWeakReference { get; set; }
   
       protected override void OnModelCreating(ModelBuilder modelBuilder) {
           base.OnModelCreating(modelBuilder);
           modelBuilder.HasChangeTrackingStrategy(ChangeTrackingStrategy.ChangingAndChangedNotificationsWithOriginalValues);
           modelBuilder.Entity<AuditEFCoreWeakReference>()
               .HasMany(p => p.AuditItems)
               .WithOne(p => p.AuditedObject);
           modelBuilder.Entity<AuditEFCoreWeakReference>()
               .HasMany(p => p.OldItems)
               .WithOne(p => p.OldObject);
           modelBuilder.Entity<AuditEFCoreWeakReference>()
               .HasMany(p => p.NewItems)
               .WithOne(p => p.NewObject);
           modelBuilder.Entity<AuditEFCoreWeakReference>()
               .HasMany(p => p.UserItems)
               .WithOne(p => p.UserObject);
       }
   }
   

   For more information on AuditDataItemPersistent and AuditEFCoreWeakReference classes, refer to the following help topic: Access the Audit Log In the Database.

3. Register the Audit Trail Module in the ASP.NET Core Blazor and WinForms application projects:

   File: MySolution.Blazor.Server/Startup.cs., MySolution.Win/Startup.cs

   C# (Blazor)

   public void ConfigureServices(IServiceCollection services) {-+
       // ...
       services.AddXaf(Configuration, builder => {
           // ...
           builder.Modules
               .AddAuditTrailEFCore()
       }
       // ...
   }
   

   C# (WinForms)

   public static WinApplication BuildApplication(string connectionString) {
       var builder = WinApplication.CreateBuilder();
       // ...
       builder.Modules
           .AddAuditTrailEFCore()
   }
   // ...
   

   Tip

   See the following topic for information on alternative ways to register a module: Ways to Register a Module.

4. In both files, locate the code that configures the object space provider and replace the call to WithDbContext with WithAuditedDbContext as follows:

   File: MySolution.Blazor.Server/Startup.cs., MySolution.Win/Startup.cs

   C# (Blazor)

   public void ConfigureServices(IServiceCollection services) {-+
       // ...
       services.AddXaf(Configuration, builder => {
           // ...
           builder.ObjectSpaceProviders
               .AddSecuredEFCore().WithAuditedDbContext(contexts => {
                   contexts.Configure<MySolutionEFCoreDbContext, MySolutionAuditingDbContext>(
                       (serviceProvider, businessObjectDbContextOptions) => {
                           string connectionString = null;
                           if (Configuration.GetConnectionString("ConnectionString") != null) {
                               connectionString = Configuration.GetConnectionString("ConnectionString");
                           }
   
                           ArgumentNullException.ThrowIfNull(connectionString);
                           businessObjectDbContextOptions.UseSqlServer(connectionString);
                           businessObjectDbContextOptions.UseChangeTrackingProxies();
                           businessObjectDbContextOptions.UseObjectSpaceLinkProxies();
                           businessObjectDbContextOptions.UseLazyLoadingProxies();
                       },
                       (serviceProvider, auditHistoryDbContextOptions) => {
                           string connectionString = null;
                           if (Configuration.GetConnectionString("ConnectionString") != null) {
                               connectionString = Configuration.GetConnectionString("ConnectionString");
                           }
   
                           ArgumentNullException.ThrowIfNull(connectionString);
                           auditHistoryDbContextOptions.UseSqlServer(connectionString);
                           auditHistoryDbContextOptions.UseChangeTrackingProxies();
                           auditHistoryDbContextOptions.UseObjectSpaceLinkProxies();
                           auditHistoryDbContextOptions.UseLazyLoadingProxies();
                       });
                   // ...
               })
           // ...  
       }
       // ...
   }
   

   C# (WinForms)

   public static WinApplication BuildApplication(string connectionString) {
       // ...
       builder.ObjectSpaceProviders
           .AddSecuredEFCore().WithAuditedDbContext(contexts => {
               contexts.Configure<MySolutionEFCoreDbContext, MySolutionAuditingDbContext>(
                   (application, businessObjectDbContextOptions) => {
                       businessObjectDbContextOptions.UseSqlServer(connectionString);
                       businessObjectDbContextOptions.UseChangeTrackingProxies();
                       businessObjectDbContextOptions.UseObjectSpaceLinkProxies();
                   },
                   (application, auditHistoryDbContextOptions) => {
                       auditHistoryDbContextOptions.UseSqlServer(connectionString);
                       auditHistoryDbContextOptions.UseChangeTrackingProxies();
                       auditHistoryDbContextOptions.UseObjectSpaceLinkProxies();
                   }
               );
           })
           // ...
   }
   

5. Run the application and click the Reports | Audit Event navigation item. The invoked list view contains change history for audited objects.

ASP.NET Core Blazor

WinForms

Note

The AuditInformationReadonlyViewController does not allow users to create, edit, or delete IAuditDataItemPersistent objects from the UI.

Display Change History in the Object Detail View

Follow the steps below to show the history of an object in its detail view:

1. Add the AuditDataItemPersistent collection property to your business class.

   C#

   using System;
   using System.Collections.Generic;
   using System.ComponentModel;
   using System.ComponentModel.DataAnnotations;
   using System.ComponentModel.DataAnnotations.Schema;
   using DevExpress.ExpressApp;
   using DevExpress.Persistent.Base;
   using DevExpress.Persistent.BaseImpl.EF;
   using DevExpress.Persistent.BaseImpl.EFCore.AuditTrail;
   // ...
   [DefaultClassOptions]
   public class MyBusinessObject : BaseObject {
       public virtual string StringProperty { get; set; }
   
       [CollectionOperationSet(AllowAdd = false, AllowRemove = false)]
       [NotMapped]
       public virtual IList<AuditDataItemPersistent> ChangeHistory {
           get { return AuditDataItemPersistent.GetAuditTrail(ObjectSpace, this); }
       }
   }
   
   // Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.
   

2. In applications with the Security System, configure permissions for non-administrative user roles so users can read information on their changes only.

   File: MySolution.Module/DatabaseUpdater/Updater.cs

   C#

   using DevExpress.Persistent.BaseImpl.EFCore.AuditTrail;
   // ...
   public class Updater : ModuleUpdater {
       // ...
       public override void UpdateDatabaseAfterUpdateSchema() {
           base.UpdateDatabaseAfterUpdateSchema();
           // ...
           PermissionPolicyRole userRole = ObjectSpace.FirstOrDefault<PermissionPolicyRole>(role => role.Name == "Users");
           if(userRole == null) {
               defaultRole = ObjectSpace.CreateObject<PermissionPolicyRole>();
               // ...
               defaultRole.AddTypePermission<AuditDataItemPersistent>(SecurityOperations.Read, SecurityPermissionState.Deny);
               defaultRole.AddObjectPermissionFromLambda<AuditDataItemPersistent>(SecurityOperations.Read, a => a.UserObject.Key == CurrentUserIdOperator.CurrentUserId().ToString(), SecurityPermissionState.Allow);
               defaultRole.AddTypePermission<AuditEFCoreWeakReference>(SecurityOperations.Read, SecurityPermissionState.Allow);
           }
       }
   }
   

The images below demonstrate the result:

ASP.NET Core Blazor

WinForms

Tip

You can also access the audit log in the database directly if you do not want to display history in the UI.