JSONAPI: Relationship IDs ignore as: :id option

[dajinchu]

I'm using the as: option with :id inside a has_many relationship:

Representer

class ParentRepresenter < Roar::Decorator
  include Roar::JSON::JSONAPI
  type :parents

  has_many :children do
  type :children

  property :alias_id, as: :id
  link :self do
    parent_child_url(represented.parent.id, represented.alias_id)
  end
end

Output of respond_with

{
  "data": {
    "relationships": {
      "documents": {
        "data": [
          {
            "type": "documents",
            "id": ""
          }
        ],
        "links": {
          "self": "http://127.0.0.1:3000/parent/57879b4a3bb752aaa6e24a35/child/0"
        }
      }
    }
  },
  "included": [
    {
      "type": "documents",
      "id": "0",
      "attributes": {},
      "links": {
        "self": "http://127.0.0.1:3000/parent/57879b4a3bb752aaa6e24a35/child/0"
      }
    }
  ]
}

The ID is properly 0 in the included array, but empty in relationships.

Note:
I'm using roar-rails with the master branch of roar.
I'm also doing something a bit weird with the child IDs in my API. For each parent, they count up from 0, and so are not unique amongst all children, but are accessed through both the child and parent ID, ie. parent/:parent_id/children/child_id. That is why the child ID needs to be aliased, as they are stored in the database using unique ids, but only this separate index will be exposed through API.

[ghost]

I confirm the same behavior with essentially the same setup

[myabc]

This issue was moved to trailblazer/roar-jsonapi#6