How do I create an expression tree for run time sorting?

Question

Using Entity Framework 4, I\'m trying to implement dynamic sorting based on a collection of member names. Basically, the user can select fields to sort and the order of the

Answer 1

Is exactly what I needed Kevin. What I noticed is that if you use the orderby it only takes the last orderby selection.

I added this method (ThenBy) to mine and it seems to work well

public static IQueryable ThenBy(this IQueryable source, string sortProperty, ListSortDirection sortOrder)
    {
        var type = typeof(T);
        var property = type.GetTypeInfo().GetDeclaredProperty(sortProperty);
        var parameter = Expression.Parameter(type, "p");
        var propertyAccess = Expression.MakeMemberAccess(parameter, property);
        var orderByExp = Expression.Lambda(propertyAccess, parameter);
        var typeArguments = new Type[] { type, property.PropertyType };
        var methodName = sortOrder == ListSortDirection.Ascending ? "ThenBy" : "ThenByDescending";
        var resultExp = Expression.Call(typeof(Queryable), methodName, typeArguments, source.Expression, Expression.Quote(orderByExp));

        return source.Provider.CreateQuery(resultExp);
    }