fixed for non-regular primary key with test

lib/paper_trail.ex

@@ -322,7 +322,7 @@ defmodule PaperTrail do
     %Version{
       event: "update",
       item_type: changeset.data.__struct__ |> Module.split() |> List.last(),
-      item_id: get_model_id_from_changeset(changeset),
+      item_id: get_model_id(changeset.data),
       item_changes: changeset.changes,
       originator_id:
         case originator_ref do
@@ -382,8 +382,4 @@ defmodule PaperTrail do
   def get_model_id(model) do
     Map.get(model, List.first(model.__struct__.__schema__(:primary_key)))
   end
-
-  def get_model_id_from_changeset(changeset) do
-    get_model_id(changeset.data)
-  end
 end

priv/uuid_repo/migrations/20170525133833_create_uuid_products.exs

@@ -8,5 +8,12 @@ defmodule PaperTrail.UUIDRepo.Migrations.CreateUuidProducts do
 
       timestamps()
     end
+
+    create table(:items, primary_key: false) do
+      add :item_id, :binary_id, primary_key: true
+      add :title, :string, null: false
+
+      timestamps()
+    end
   end
 end

test/paper_trail/uuid_test.exs

@@ -14,6 +14,7 @@ defmodule PaperTrailTest.UUIDTest do
     repo().delete_all(Version)
     repo().delete_all(Admin)
     repo().delete_all(Product)
+    repo().delete_all(Item)
     :ok
   end
 
@@ -47,4 +48,14 @@ defmodule PaperTrailTest.UUIDTest do
 
     assert version.admin == admin
   end
+
+  test "versioning models that have a non-regular primary key" do
+    item =
+      %Item{}
+      |> Item.changeset(%{title: "hello"})
+      |> PaperTrail.insert!()
+
+    version = Version |> last |> repo().one
+    assert version.item_id == item.item_id
+  end
 end

test/support/uuid_models.exs

@@ -34,3 +34,21 @@ defmodule Admin do
     |> validate_required([:email])
   end
 end
+
+defmodule Item do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  @primary_key {:item_id, :binary_id, autogenerate: true}
+  schema "items" do
+    field(:title, :string)
+
+    timestamps()
+  end
+
+  def changeset(model, params \\ %{}) do
+    model
+    |> cast(params, [:title])
+    |> validate_required(:title)
+  end
+end