Order a queryable based on a string input. "Members" can be a value like: "Name, Company.Type desc, Company.Name". Handles nested property references, ascending/descending and nullable/nonnullable targets.

Order.cs

private IQueryable<T> Order<T>(IQueryable<T> list, string members)
{
    var param = Expression.Parameter(list.ElementType, "r");
    bool thenMode = false;

    foreach (var member in members.Split(','))
    {
        MemberExpression memberExpression = null;
        var chop = member.Split(' ');
        foreach (var memberPart in chop[0].Split('.'))
        {
            memberExpression = Expression.PropertyOrField((Expression)memberExpression ?? param, memberPart);
        }

        bool sortDescending = false;
        if (chop.Length > 1)
        {
            sortDescending = chop[1].IndexOf("desc", StringComparison.InvariantCultureIgnoreCase) > -1;
        }

        string command;
        if (thenMode)
        {
            command = sortDescending ? "ThenByDescending" : "ThenBy";
        }
        else
        {
            command = sortDescending ? "OrderByDescending" : "OrderBy";
        }

        var exp = Expression.Lambda(memberExpression, param);
        var resultExpression = Expression.Call(typeof(Queryable), command, new[] { typeof(T), memberExpression.Type }, list.Expression, Expression.Quote(exp));

        list = list.Provider.CreateQuery<T>(resultExpression);
        thenMode = true;
    }
            
    return list;
}