Yes, but thinking a bit longer term, once you have the sample IDs, how are you going to query the sample information? You will need to, either request the metadata obj and then ask for the sample, or we will need the sample obj...

I'd say you can do exactly the same thing on qiita_pet by requesting the metadata obj and then asking for the sample ids there, with the advantage that you can also ask the metadata obj for the extra info, if you also need to show that information.

In terms of code structure, and SQL structure, the study obj doesn't now anything about samples. The object that nows about samples is the metadata obj, so that is why it doesn't make sense to have the study aware of the samples here.