I'm attempting to perform dynamic sorting of data that I'm putting into grids into our MVC UI. Since MVC is abstracted from everything else via WCF, I've created a couple utility classes and extensions to help with this. The two most important things (slightly simplified) are as follows:

    public static IQueryable<T> ApplySortOptions<T, TModel, TProperty>(this IQueryable<T> collection, IEnumerable<ISortOption<TModel, TProperty>> sortOptions) where TModel : class
    {
        var sortedSortOptions = (from o in sortOptions
                                 orderby o.Priority ascending
                                 select o).ToList();

        var results = collection;

        foreach (var option in sortedSortOptions)
        {
            var currentOption = option;
            var propertyName = currentOption.Property.MemberWithoutInstance();
            var isAscending = currentOption.IsAscending;

            if (isAscending)
            {
                results = from r in results
                          orderby propertyName ascending 
                          select r;
            }
            else
            {
                results = from r in results
                          orderby propertyName descending 
                          select r;
            }
        }

        return results;
    }


public interface ISortOption<TModel, TProperty> where TModel : class
{
    Expression<Func<TModel, TProperty>> Property { get; set; }
    bool IsAscending { get; set; }
    int Priority { get; set; }
}

I've not given you the implementation for MemberWithoutInstance() but just trust me in that it returns the name of the property as a string. :-)

Following is an example of how I would consume this (using a non-interesting, basic implementation of ISortOption<TModel, TProperty>):

var query = from b in CurrentContext.Businesses
            select b;

var sortOptions = new List<ISortOption<Business, object>>
                      {
                          new SortOption<Business, object>
                              {
                                  Property = (x => x.Name),
                                  IsAscending = true,
                                  Priority = 0
                              }
                      };

var results = query.ApplySortOptions(sortOptions);

As I discovered with this question, the problem is specific to my orderby propertyName ascending and orderby propertyName descending lines (everything else works great as far as I can tell). How can I do this in a dynamic/generic way that works properly?