Bruno - the problem is with the region field below. The reference uses the resource_uri rather than the id and the latter is what I'd want.
Josh - I was using backbone-tastypie and actually had to fork it to get it to work the way I wanted it to. Basically, I wanted to have an object id in the URL and I didn't want that to be the resource_uri. So, in my router, when I handle a details view (with the object id in the URL), I only have access to the id and not the resource_uri. However, backbone-tastypie makes it such that models are keyed by resource_uri and not id in collections. So, looking up my model would require me to construct a resource_uri out of the id ...
Thanks,
Meetesh