Right, so this is for editing the relationship, its /post/:id/relationships/comments. However, that isn’t for creating new things, I just reread your initial post and now I see what you mean. This should likely be done as POST /comments specifying a post id to be the most REST-ish. We can add the option to ignore the base-route for some routes, that way on comment you could do: create :create, route: "/post/:post_id/comments", base_route?: false and have it pass the post_id through.
