Access nested properties with dynamic lambda using Linq.Expression

Question

Let's assume that I have two classes:

class person
{
    int ID
    string name
    Address address
}
class address
{
    int ID
    string street
    string country
}

These classes are more or less given, they are mapped via nHibernate to be honest :)

In a grid (datatables.net as base) I would like to have a type-independent sorting.

Therefore I created a lambda expression:

  var param = Expression.Parameter(typeof(T), typeof(T).Name);
  var sortExpression = Expression.Lambda<Func<T, object>>
                              (Expression.Convert(Expression.Property(param, "Property to sort"), typeof(object)), param);

If I pass Person as Type T and replace the "Property to sort" with "name" it works fine (creates a correct lambda). If the Property to sort is "address.street" it won't work, throw me the following error:

Property 'address.street' is not defined for type 'person'

I see only one solution so far, but not clear enough... I would try to split the string which contains the Property-Name (split by .)

Can anyone give a better solution? I need to add the sortExpression to an IQueryable object query.OrderBy(sortExpression).

Not sure if my title is clear, please go ahead and correct it.

Thanks in advance.

Answer 1

It seems to me you're trying to rewrite Microsoft DynamicQuery. Why not just use that instead?

Here's an example:

IQueryable<Foo> myQuery = GetHibernateQuery();
myQuery = myQuery.OrderBy("address.street");

Answer 2

What is not clear?

You have to split it and then use:

Expression.Property(Expression.Property(param, "address"), "street")