We have an Ash resource defined as polymorphic:

defmodule  MyApp.Location do

  use Ash.Resource, data_layer: AshPostgres.DataLayer

  postgres do
    repo MyApp.Repo
    polymorphic? true
  end

  attributes do
    uuid_primary_key :id
    attribute :resource_id, :uuid do
      allow_nil? false
      private? true
    end
    attribute :x, :float
    attribute :y, :float
  end

  ...

That is then used by 2 or 3 other resources, e.g.

defmodule  MyApp.Event do

  use Ash.Resource, data_layer: AshPostgres.DataLayer

  postgres do
    repo MyApp.Repo
    table "events"
  end

  attributes do
    uuid_primary_key :id
    attribute :when, :utc_datetime, allow_nil?: false, default: &DateTime.utc_now/0
    attribute :what, :string
    attribute :who, :string
  end

  relationships do
    has_one :location, Location do
      relationship_context %{data_layer: %{table: "event_locations"}}
      destination_attribute :resource_id
    end
  end

Is it possible to use the references config block somehow to delete Locations when the owning Event is deleted?

If it wasn’t polymorphic, we could do something like this in the Location resource, but given it references a specific relationship it won’t work with a polymorphic resource:

  postgres do
    repo MyApp.Repo
    # polymorphic? true

    references do
      reference :event, on_delete: :delete
    end
  end

The obvious (to me) alternative is setting up a destroy action on the Event resource that deletes the associated Location first, but then that has to be repeated for every other resource that may use Location which kinda defeats the purpose of using a polymorphic resource in the first place.

Edit: The destroy action isn’t so easy to get right either - how do you inject the datalayer[:table] context to ensure the delete is applied to the right table?