DeleteValidator: Add internal helper field after validation.

lib/pleroma/web/activity_pub/object_validators/delete_validator.ex

@@ -5,6 +5,7 @@
 defmodule Pleroma.Web.ActivityPub.ObjectValidators.DeleteValidator do
   use Ecto.Schema
 
+  alias Pleroma.Activity
   alias Pleroma.Web.ActivityPub.ObjectValidators.Types
 
   import Ecto.Changeset
@@ -18,6 +19,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.DeleteValidator do
     field(:actor, Types.ObjectID)
     field(:to, Types.Recipients, default: [])
     field(:cc, Types.Recipients, default: [])
+    field(:deleted_activity_id)
     field(:object, Types.ObjectID)
   end
 
@@ -26,12 +28,26 @@ def cast_data(data) do
     |> cast(data, __schema__(:fields))
   end
 
+  def add_deleted_activity_id(cng) do
+    object =
+      cng
+      |> get_field(:object)
+
+    with %Activity{id: id} <- Activity.get_create_by_object_ap_id(object) do
+      cng
+      |> put_change(:deleted_activity_id, id)
+    else
+      _ -> cng
+    end
+  end
+
   def validate_data(cng) do
     cng
     |> validate_required([:id, :type, :actor, :to, :cc, :object])
     |> validate_inclusion(:type, ["Delete"])
     |> validate_same_domain()
     |> validate_object_or_user_presence()
+    |> add_deleted_activity_id()
   end
 
   def validate_same_domain(cng) do

test/web/activity_pub/object_validator_test.exs

@@ -21,7 +21,9 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidatorTest do
     end
 
     test "it is valid for a post deletion", %{valid_post_delete: valid_post_delete} do
-      assert match?({:ok, _, _}, ObjectValidator.validate(valid_post_delete, []))
+      {:ok, valid_post_delete_u, _} = ObjectValidator.validate(valid_post_delete, [])
+
+      assert valid_post_delete_u["deleted_activity_id"]
     end
 
     test "it is valid for a user deletion", %{valid_user_delete: valid_user_delete} do