db4o: Query on abstract class type: no results

Question

I stored a bunch of objects of various classes that inherited from the abstract class Creative. I wanted to see what was stored so I wrote a method like so:

    public void GetCreativeTypes()
    {
        var types = from Creative c in original.AsQueryable<Creative>()
                    select string.Format("{0}: {1}", c.CreativeType, c.GetType());

        foreach (var type in types.Distinct())
        {
            Debug.WriteLine(type);
        }

        return;
    }

...but this returns no results. I have also tried:

    public void GetCreativeTypes()
    {
        var types = from Creative c in original
                    select string.Format("{0}: {1}", c.CreativeType, c.GetType());

        foreach (var type in types.Distinct())
        {
            Debug.WriteLine(type);
        }

        return;
    }

with the same results. How can I get the results I want?

Objects in original collection would be like

public class ImageCreative : Creative{}
public class FlashCreative : Creative{}

...etc.

Answer 1

It turned out to be unrelated to the query. The documentation stated that the records did not need to be committed (just close the container), but once I committed them they were queryable. That was a headscratcher for me.