Missing links for related relationship data

[sevenseacat]

Describe the bug

The example for compound documents and relationships in the JSON:API docs show that we should be providing links for how to fetch related data, if they exist.

eg.

• a relationship route should appear as a self route in the links
• a related route should appear as a related route in the links

This is important for discoverability of relationships in the API.

To Reproduce

For an Artist resource defined like so:

  json_api do
    type "artist"

    routes do
      base "/artists"
      get :read
      related :albums, :read
    end
  end

An API response to get an artist returns the following relationship data:

    "relationships": {
      "albums": {
        "links": {},
        "meta": {}
      }
    }

Expected behavior

I would expect the links in the relationship data to include a related link like:

{
  "links": {
    "related": "http://localhost:4000/api/artists/the_artist_id/albums"
  }
}

In a similar/related vein, I'd expect the links for included resources to be populated with self links.

Runtime

• Elixir version 1.17.0-otp-27
• Erlang version 27.0
• OS macOS Sonoma
• Ash version 3.0.12
• AshJsonApi version main branch at commit https://github.com/ash-project/ash_json_api/commit/0bbdd179fa9fe06d78f5881fd02b03ebfeeee747

[zachdaniel]

Alright, so this one was primarily a documentation issue. I've added a very high level guide for this, as I'm a bit low on time today. It does, however, explain that links are generated from primary? routes. So to have your links generated, you'd want to designate the appropriate routes as primary? true

[sevenseacat]

I didn't even know that was an option! cheers 👍