From a Model Value, I should be able to access the enclosing Thing

Summary: This is a subtle but significant problem pointed out by Eric. Sometimes, when you are building a sophisticated Model Type, you really want to be able to access contextual information that exists on the enclosing Bundle. For example, in his highly-customized Review Types, he wants to be able to display the current Average -- but the Average Property is on the Thing, not on the Review, and the Review currently has no way of getting to the enclosing Thing, even in workaround.

This is a fairly hard problem, and arises from the core assumptions of Model Types. It isn't clear what the correct solution is, but it likely has something to do with exposing the "parent" or "enclosing" ancestors in the context. There may be a more general concept fighting to break out here, whereby the Context in QL processing is "additive", and code can look up the chain.

Ideally, we would DWIM so that, eg, UV Review could simply access the UV Rating Summary on the ancestor Thing, and it would automatically be found, but that sort of automatic lookup need to be done with great care, especially if we generalize the concept. It would be very powerful, but also very dangerous, to automatically resolve Properties against the first match up the chain.