audit.cs

    public override int SaveChanges()
    {
        using (var scope = new TransactionScope())
        {
            var addedEntries = ChangeTracker.Entries().Where(e => e.State == EntityState.Added).ToList();
            var modifiedEntries = ChangeTracker.Entries().Where(e => e.State == EntityState.Deleted || e.State == EntityState.Modified).ToList();

            foreach (var entry in modifiedEntries)
            {
                ApplyAuditLog(entry);
            }

            int changes = base.SaveChanges();
            foreach (var entry in addedEntries)
            {
                ApplyAuditLog(entry, LogOperation.CreateEntity);
            }

            base.SaveChanges();
            scope.Complete();
            return changes;
        }
    }

    private void ApplyAuditLog(DbEntityEntry entry)
    {
        LogOperation operation;
        switch (entry.State)
        {
            case EntityState.Added:
                operation = LogOperation.CreateEntity;
                break;
            case EntityState.Deleted:
                operation = LogOperation.DeleteEntity;
                break;
            case EntityState.Modified:
                operation = LogOperation.UpdateEntity;
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }

        ApplyAuditLog(entry, operation);
    }

    private void ApplyAuditLog(DbEntityEntry entry, LogOperation logOperation)
    {
        ILog entity = entry.Entity as ILog;

        if (entity != null)
        {
            AuditLog log = new AuditLog
            {
                Created = DateTime.Now,
                Entity = entry.Entity.GetType().Name,
                EntityId = entity.Id,
                Operation = logOperation,
            };
            AuditLog.Add(log);
        }
    }