It was not working. I fixed it like below:

defmodule Hr.Extensions.CustomFields.Transformers.AddCustomFields do
  use Spark.Dsl.Transformer
  import Ash.Expr

  @doc """
  Automatically add relationship to the FieldResourceRecord on any given resource
  """
  def transform(dsl) do
    Ash.Resource.Builder.add_new_relationship(
      dsl,
      :has_many,
      :fields,
      Hr.Fields.FieldResourceRecord,
      destination_attribute: :resource_record_id,
      filters: expr(resource_name == get_resource_name(dsl))
    )
  end

  defp get_resource_name(dsl) do
    dsl.persist.module
    |> Atom.to_string()
    |> String.replace("Elixir.", "")
  end
end

Also the error message says it requires filter options even if it has been passed. So, I figured out that the issues is in the error messages.

The error message should report missing destination_attribute instead of destination_field, and it should report missing filters instead of filter.

Error showing missing filter instead of filters

image1200×989 86.3 KB

Error showing destination field missing nstead of destination_attribute

image1200×989 86.9 KB