Failing to generate filter object for nested relationship

[diogomrts]

The ash_json_api extension is failing to generate the filter object for a two-times nested relationship. For example, given the relationship where Author has many Posts, and Post belongs to Blog, the Authors endpoint generated should include a reference to the blog-filter, but it was never generated.

To Reproduce

1. Define a resource where Author has many Posts.
2. Define that Post belongs to Blog.
3. Generate an API for Authors.
4. Observe that the blog-filter is not generated in the Authors endpoint.

This are the Resources i tried with:

Author

defmodule TestRepo.Support.Author do
  use Ash.Resource,
    domain: TestRepo.Support,
    extensions: [AshJsonApi.Resource]

  json_api do
    type("author")

    routes do
      base "/authors"
      index :read
    end
  end

  actions do
    default_accept(:*)
    defaults([:create, :read, :update, :destroy])
  end

  attributes do
    uuid_primary_key(:id, writable?: true)
    attribute(:name, :string, public?: true)
  end

  relationships do
    has_many(:posts, TestRepo.Support.Post, public?: true)
  end
end

Post

defmodule TestRepo.Support.Post do
  use Ash.Resource,
    domain: TestRepo.Support,
    extensions: [AshJsonApi.Resource]

  json_api do
    type("post")
  end

  actions do
    default_accept(:*)
    defaults([:create, :read, :update, :destroy])
  end

  attributes do
    uuid_primary_key(:id, writable?: true)
    attribute(:name, :string, public?: true)
  end

  relationships do
    belongs_to :author, TestRepo.Support.Author, public?: true
    belongs_to :blog, TestRepo.Support.Blog, public?: true
  end
end

Blog

defmodule TestRepo.Support.Blog do
  use Ash.Resource,
    domain: TestRepo.Support,
    extensions: [AshJsonApi.Resource]

  json_api do
    type("blog")

    routes do
      base "/blogs"
      index :read
    end
  end

  actions do
    default_accept(:*)
    defaults([:create, :read, :update, :destroy])
  end

  attributes do
    uuid_primary_key(:id, writable?: true)
    attribute(:name, :string, public?: true)
  end

  relationships do
    has_many :posts, TestRepo.Support.Post, public?: true
  end
end

Runtime

• Elixir version: 1.16.3
• Erlang version: erts-13.2.2.9
• OS: MacOs
• Ash version: 3.4.1
• ash_json_api version: 1.4.4