I want to make my RESTful API very predictable. What is the best practice for deciding when to make a segmentation of data using the URI rather than by using query params.
It makes sense to me that system parameters that support pagination, sorting, and grouping be after the '?' But what about fields like 'status' and 'region' or other attributes that segment your collection? If those are to be query params as well, what is the rule of thumb on knowing when to use path params?
In a REST API, you shouldn't be overly concerned by predictable URI's. The very suggestion of URI predictability alludes to a misunderstanding of RESTful architecture. It assumes that a client should be constructing URIs themselves, which they really shouldn't have to.
However, I assume that you are not creating a true REST API, but a 'REST inspired' API (such as the Google Drive one). In these cases the rule of thumb is 'path params = resource identification' and 'query params = resource sorting'. So, the question becomes, can you uniquely identify your resource WITHOUT status / region? If yes, then perhaps its a query param. If no, then its a path param.