REST conventions for a friends list

Question

I have a database (ORM) with users which look like this:

UserEntity (
   id: UUID,
   name: String,
   phoneNumber: String,
   friends: List<UserEntity>
)

I also have the following friends endpoints:

GET /user/<userId>/friends (returns a list of UUID's for all friends the user has)
POST /user/<userId>/friends?friendId=<friendId> (saves a new friend to the friends list)
DELETE /user/<userId>/friends?friendId=<friendId> (deletes a friend from the friends list)

Now I asked myself: is this the correct way of implementing a RESTful friend list and what is a good REST convention to obtain the profile of a friend. Should the friend resource be reached from the following path:

GET /user/<userId>/friends/<friendId> 

Or from this path:

GET /user/<friendId>

Both of the given endpoints from above give back the same resource (a profile) but which one should I choose? I am diving deeper into REST conventions but I didn't find any clear answer for this. I dont't even know if my current REST design is correct. Thanks in advance for your help.

Answer 1

What you are talking about I would call nice URL convention. https://en.wikipedia.org/wiki/Clean_URL It has nothing to do with REST https://www.ics.uci.edu/~fielding/pubs/dissertation/fielding_dissertation.pdf and I have no idea why people think it has. From the REST point of view it would be equally good to do something like GET|PUT|DELETE /dsgvs23w?x235rwef=1&aegs234523f=2 and decide which URL to follow based on the metadata that describes it. If you violate HATEOAS, then you don't have a REST API.

As of the nice URL convention I would do something like GET /friendships/?user=1 and GET|PUT|DELETE /friendships/1+2 and add some extra info about the friendship e.g. strength=BFF, duration=20y, etc. But there are infinite good solutions for this and it really depends on your needs.