Related endpoints for STI resources do not yield proper types

[alexssung]

Following up on #507

Given a model Animal with subclasses Cat and Dog, types get returned properly when querying directly for animals - e.g. hitting endpoint "api/animals" responds with types "cats" and "dogs" in the payload.

However, this behavior is not consistent when hitting the related endpoints of a resource - e.g. hitting "api/zoos/7/animals" responds with only type "animals" in the payload.

Currently, I am including "type" in the attributes object, which raises a warning and also breaks the JSON API specs. Is there a better workaround for this?

[Subtletree]

I'm hitting this too, @alexssung Did you ever work around this?

[Subtletree]

Perhaps #748 could also be made to return the correct type for relations.

My hacky workaround:

class CommentResource < JSONAPI::Resource
  has_one :post, always_include_linkage_data: true, polymorphic: true
  ...
end

class Comment < ApplicationRecord
  # Remove this once https://github.com/cerebris/jsonapi-resources/issues/772 is fixed
  def post_type=(_value)
  end
  ...
end

Haven't tested with has_many

[cghnassia]

Hello,
Has someone found a workaround for an hasMany relationship ? I am trying to get the right type as well as the attributes defined or the child resource when I include the relationship. Today I get the type and the attributes from the parent resource.
I tried with polymorphic but without any success...