public TEntity FindByKey(int id)
        {
            var item = Expression.Parameter(typeof(TEntity), "entity");
            var prop = Expression.Property(item, typeof(TEntity).Name + "Id");
            var value = Expression.Constant(id);
            var equal = Expression.Equal(prop, value);
            var lambda = Expression.Lambda<Func<TEntity, bool>>(equal, item);

            return GetAsNoTrackingQueryable().SingleOrDefault(lambda);
        }