In this new post to her site Lorna Mitchell tries to help answer a question she got on Twitter about "subqueries" in REST API calls. In this case, a subquery is requesting just a subset of the data from a resource.

REST is all about representations of resources. They might come in different formats, and they might appear at their own URI as well as in one or more collections, but essentially you just get a representation of a thing. This is great, apart from when it isn't. [...] There are a couple of tactics that I deploy each time I need to solve one of these problems, but they all revolve around remodelling the resource structure. Just as we sometimes move fields around for database design or normalisation, we can do exactly the same with a RESTful service to make the resulting output make more sense to consumers.

She talks about one method that lets the consumer change the "verbosity" of the response and another that splits these pieces out into separate sub-resources for each section. She suggests a third option as well, the nesting of likely data - that is related data the user might most likely want along with what they requested.