gistfile1.cs

        public override int SaveChanges()
        {
            //this goes through and updates the created on / modified on dates.
            this.ChangeTracker.Entries<BaseModel>().ForEach(x =>
            {
                if (x.State == System.Data.EntityState.Added)
                {
                    x.Entity.CreatedOn = DateTime.UtcNow;
                }

                x.Entity.ModifiedOn = DateTime.UtcNow;
            });

            return base.SaveChanges();
        }