Implementing a Base Class with Entity Framework

I want to add a bunch of audit fields to all of my tables.  Here's how I did it with a base class.  Note that the base class must have a key column. The subclass does not have an ID explicitly; it inherits the ID column from the base class.

The call to MapInheritedProperties will put the inherited properties directly on the subclass table. 

	namespace My.Models.BaseModels
	{
	public class AuditableEntity
	{
	public int Id { get; set; }
	public DateTime CreatedDt { get; set; }
	public string CreatedBy { get; set; }
	public DateTime RevisedDt { get; set; }
	public string RevisedBy { get; set; }
	}
	}

view raw AuditableEntity.cs hosted with ❤ by GitHub

	namespace My.Models
	{
	public class Claim : AuditableEntity
	{
	public ClaimType ClaimType { get; set; }
	public DateTime ClaimDate { get; set; }
	}
	}

view raw Claim.cs hosted with ❤ by GitHub

	namespace My.DataAccess
	{
	public class MyDbContext : DbContext
	{
	public MyDbContext() : base("database") // Web.config connection string
	{
	}
	public DbSet<Claim> Claims { get; set; }
	protected override void OnModelCreating(DbModelBuilder modelBuilder)
	{
	// To get the Audit fields directly on the Table.
	modelBuilder.Entity<Claim>().Map(m => m.MapInheritedProperties()).ToTable("Claim");
	}
	public override int SaveChanges()
	{
	var entities = ChangeTracker.Entries().Where(x => x.Entity is AuditableEntity && (x.State == EntityState.Added || x.State == EntityState.Modified));
	var currentUsername = HttpContext.Current != null && HttpContext.Current.User != null
	? HttpContext.Current.User.Identity.Name
	: "Anonymous";
	foreach (var entity in entities)
	{
	if (entity.State == EntityState.Added)
	{
	((AuditableEntity)entity.Entity).CreatedDt = DateTime.Now;
	((AuditableEntity)entity.Entity).CreatedBy = currentUsername;
	}
	((AuditableEntity)entity.Entity).RevisedDt = DateTime.Now;
	((AuditableEntity)entity.Entity).RevisedBy = currentUsername;
	}
	return base.SaveChanges();
	}
	}
	}

view raw MyDbContext.cs hosted with ❤ by GitHub