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Versions

erlang 28.1
elixir 1.19.0-otp-28

Operating system

macOS 26.0.1

Current Behavior

Given a resource with an array embedded resource and static defaults:

attribute :channels, {:array, MyApp.Channel} do
  default [%{name: :web, suppressible: false}, %{name: :email, suppressible: true}]
end

The app fails to compile with the following compilation error:

== Compilation error in file lib/my_app/notification_type/assignment_posted.ex ==
** (ArgumentError) cannot escape #Reference<0.96162257.3960733698.139143>. The supported values are: lists, tuples, maps, atoms, numbers, bitstrings, PIDs and remote functions in the format &Mod.fun/arity
    (spark 2.3.5) lib/my_app/notification_type/assignment_posted.ex:1: Spark.Dsl.__before_compile__/1

This is caused by the create action on the MyApp.Channel being called at compile time via a bulk create resulting in the following extra metadata:

        __metadata__: %{
          :selected => [:name, :suppressible],
          {:bulk_create_index, #Reference<0.910774993.731906049.251376>} => 1
        }

this metadata is on the two created records which are trying to be saved as the default value of the attribute entity on the resource.

This change was caused by efcf047 AFAICT.

The user has been advised to use the 0-arity function version of defaults so that the resources are created when the :create action is called on the parent resource, rather than at compile time.

I am opening this bug to track that there is a compile error that is very difficult for a user to debug and not the fact that the behaviour has changed, because I think the old behaviour was probably wrong.

My suggested resolution is to remove the creation of default embedded records at compile time and emit an error.

Reproduction

No response

Expected Behavior

No response