bugfix: Re-add bulk_create_index metadata when running bulk creates

This is necessary when running bulk create actions with the `sorted?: true`
option, and also retains consistency with other built-in data layers

Related to ash-project/ash#2452

Author: sevenseacat

lib/data_layer.ex

@@ -2142,8 +2142,12 @@ defmodule AshPostgres.DataLayer do
                     end
 
                     # Compatibility fallback
-                    Ash.Resource.put_metadata(
-                      result_for_changeset,
+                    result_for_changeset
+                    |> Ash.Resource.put_metadata(
+                      :bulk_create_index,
+                      changeset.context[:bulk_create][:index]
+                    )
+                    |> Ash.Resource.put_metadata(
                       :bulk_action_ref,
                       changeset.context[:bulk_create][:ref]
                     )
@@ -2159,8 +2163,12 @@ defmodule AshPostgres.DataLayer do
                   end
 
                   # Compatibility fallback
-                  Ash.Resource.put_metadata(
-                    result,
+                  result
+                  |> Ash.Resource.put_metadata(
+                    :bulk_create_index,
+                    changeset.context[:bulk_create][:index]
+                  )
+                  |> Ash.Resource.put_metadata(
                     :bulk_action_ref,
                     changeset.context[:bulk_create][:ref]
                   )

test/bulk_create_test.exs

@@ -579,4 +579,21 @@ defmodule AshPostgres.BulkCreateTest do
       end)
     end
   end
+
+  describe "bulk_create with sorted?: true" do
+    test "works without error" do
+      # This test reproduces https://github.com/ash-project/ash/issues/2452
+      # generate_many uses sorted?: true which requires bulk_create_index metadata
+      results =
+        Ash.bulk_create!(
+          [%{title: "post_1"}, %{title: "post_2"}, %{title: "post_3"}],
+          Post,
+          :create,
+          return_records?: true,
+          sorted?: true
+        )
+
+      assert length(results.records) == 3
+    end
+  end
 end