Indeed I did not have the polymorphic definition defined and that was my issue:
Adding the following resolved it for me: polymorphs data, :to => %w(Book etc..) -- You received this message because you are subscribed to the Google Groups "Thinking Sphinx" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/thinking-sphinx. For more options, visit https://groups.google.com/d/optout.
