resource links on a  polymorphic belongs_to association

I wanted to start a discussion around how to handle a polymorphic belongs_to relation on a resource. 

Just returning the FK id doesn't contain the polymorphic context of the linked resource, resulting in an ambiguous link. I've implemented a simple fix that fits my needs as my polymorphic association target overrides the to_param method however if the association target doesn't then this problem still remains. 

Perhaps there is a better way of embedding the association type in the links hash? Thoughts?