I have a resource that has an attribute that is an array of embedded resources.

I have module calculation that maps the embedded resources and returns a list of values. Pretty trivial in elixir. I’d like to also implement this as an Ash expression so that can be selected (and filtered against) at the data layer (postgres).

  def calculate(records, opts, _) do
    Enum.map(records, fn record -> 
      Map.get(record, opts[:embedded_resources])
      |> Enum.map(fn embedded_resource ->
        Map.get(embedded_resource, opts[:embedded_attribute])
      end)
    end)
  end

Is this possible with Ash expressions? Or should I just normalize this and have an attribute on record that is set on create/update?

I’ve experimented with doing this as a SQL fragment but that requires unnesting the embedded resource, lateral joining tables, and grouping. Technically possible, but doesn’t make for an Ash expression.