gistfile1.cs

       public static IQueryable<TEntity> OrderBy<TEntity>(IQueryable<TEntity> source, string orderByProperty, bool desc)
        {
            string command = desc ? "OrderByDescending" : "OrderBy";
            var type = typeof(TEntity);
            var property = type.GetProperty(orderByProperty);
            var parameter = Expression.Parameter(type, "p");
            var propertyAccess = Expression.MakeMemberAccess(parameter, property);
            var orderByExpression = Expression.Lambda(propertyAccess, parameter);
            var resultExpression = Expression.Call(typeof(Queryable), command, new Type[] { type, property.PropertyType },
                                          source.Expression, Expression.Quote(orderByExpression));
            return source.Provider.CreateQuery<TEntity>(resultExpression);
        }