Type t = typeof(T);
if (t == typeof(object))
{
    t = map.GetType();
}
Console.WriteLine("Flying using a {0} map ({1})", t.Name, map);

public static IQueryable<T> OrderBy<T>(this IQueryable<T> datasource, string propertyName, SortDirection direction)
        {
            if(string.IsNullOrEmpty(propertyName))
            {
                return datasource;
            }

            var type = typeof(T);

            var property = type.GetProperty(propertyName);   //这里报异常

            if(property == null)
            {
                throw new InvalidOperationException(string.Format("Could not find a property called '{0}' on type {1}", propertyName, type));
            }

            var parameter = Expression.Parameter(type, "p");
            var propertyAccess = Expression.MakeMemberAccess(parameter, property);
            var orderByExp = Expression.Lambda(propertyAccess, parameter);

            const string orderBy = "OrderBy";
            const string orderByDesc = "OrderByDescending";

            string methodToInvoke = direction == SortDirection.Ascending ? orderBy : orderByDesc;

            var orderByCall = Expression.Call(typeof(Queryable), 
                methodToInvoke, 
                new[] { type, property.PropertyType }, 
                datasource.Expression, 
                Expression.Quote(orderByExp));

            return datasource.Provider.CreateQuery<T>(orderByCall);
        }

var type = typeof(T);
if(type == typeof(object))
{
    type = datasource.FirstOrDefault().GetType();
}