IQueryableExtensions.cs

public static class IQueryableExtensions
{
    public static IOrderedQueryable<TSource> OrderBy<TSource, TKey>(
        this IQueryable<TSource> source,
        Expression<Func<TSource, TKey>> keySelector,
        bool isAscending)
    {
        if (isAscending)
        {
            return source.OrderBy(keySelector);
        }
        else
        {
            return source.OrderByDescending(keySelector);
        }
    }
}