ActionWebService and ActiveRecord


I created a Rails application using ActiveRecords.

Now I like to create a Webservice for getting some data from rails.
I have a Wettkampfserie that has_many Wettkampf.

When I now define an API like this:
api_method :get_wettkampfserie,
:expects => [:int],
:returns => [Wettkampfserie]

It generates a WSDL with only the Wettkampfserie and without the
has_many Wettkampf.

How do I tell ActionWebService that It should also create WSDL for the
has_many assosications?

Thanks a lot.
Regards, Simon

Am I the only one with this problem?