Absinthe resolve field with batch

macros.ex

defmodule MyAppWeb.Api.Macros do
  @moduledoc """
  Not actual Absinthe middleware.
  """

  use Absinthe.Schema.Notation

  @doc """
  Macro to reuse the common pattern of preloading associations using
  a batch function using `id` as the key.
  """
  defmacro resolve_with_batch(module, function, opts \\ []) do
    key = Keyword.get(opts, :key, :id)

    quote do
      resolve(fn parent, _, _ ->
        id = Map.get(parent, unquote(key))

        batch(
          {unquote(module), unquote(function)},
          id,
          fn batch ->
            {:ok, Map.get(batch, id)}
          end
        )
      end)
    end
  end
end