[mkhattab]

I believe '/courses' and 'student/1234/courses' mean two different things. The former implies a list of courses and the later implies an association between a student and a course.

POSTing to '/courses' creates a new course. However POSTing to a 'student/1234/courses' creates a relationship/association between a student and a course.

So, it's two different things IMO and not a duplication of logic.

[3pt14159]

This isn't true. Or at least not necessarily true. If you're referring to the JSON API spec you're conflating related and relationship links. The former is strictly for GETs (GET students/5/courses) and the later is for controlling the relationship itself (PATCH students/5/relationship/courses).

See here for more information:

http://jsonapi.org/format/upcoming/#crud-updating-to-many-re...