lib/ash/resource/change/get_and_lock_for_update.ex

defmodule Ash.Resource.Change.GetAndLockForUpdate do
  @moduledoc """
  Refetches the record being updated or destroyed, and locks it for update.
  """
  use Ash.Resource.Change

  def change(changeset, _, context) do
    Ash.Changeset.before_action(changeset, fn changeset ->
      primary_key = Ash.Resource.Info.primary_key(changeset.resource)
      pkey_values = changeset.data |> Map.take(primary_key) |> Map.to_list()

      case changeset.api.get(
             changeset.resource,
             pkey_values,
             tracer: context[:tracer],
             tenant: context[:tenant],
             authorize?: false,
             lock: :for_update
           ) do
        {:ok, record} ->
          %{changeset | data: record}

        {:error, error} ->
          Ash.Changeset.add_error(changeset, error)
      end
    end)
  end
end