Fix item_id for composite primary keys

lib/paper_trail/serializer.ex

@@ -2,12 +2,13 @@ defmodule PaperTrail.Serializer do
   @moduledoc false
   import Ecto.Query
 
+  alias Ecto.UUID
   alias PaperTrail.RepoClient
   alias PaperTrail.Version
 
   @type options :: PaperTrail.options()
 
-  @default_ignored_ecto_types [Ecto.UUID, :binary_id, :binary]
+  @default_ignored_ecto_types [UUID, :binary_id, :binary]
 
   def make_version_struct(%{event: "insert"}, model, options) do
     originator = RepoClient.originator()
@@ -221,17 +222,37 @@ defmodule PaperTrail.Serializer do
   def get_item_type(%Ecto.Changeset{data: data}), do: get_item_type(data)
   def get_item_type(%schema{}), do: schema |> Module.split() |> List.last()
 
+  @spec get_model_id(Ecto.Changeset.t() | struct()) :: String.t() | integer()
   def get_model_id(%Ecto.Changeset{data: data}), do: get_model_id(data)
 
   def get_model_id(model) do
-    {_, model_id} = List.first(Ecto.primary_key(model))
+    model_id =
+      case Ecto.primary_key(model) do
+        [{_, model_id}] ->
+          model_id
+
+        composite_primary_keys ->
+          composite_primary_keys
+          |> Enum.sort_by(fn {field, _value} -> field end, :asc)
+          |> Enum.map_join(":", fn {_field, value} -> to_string(value) end)
+      end
 
     case PaperTrail.Version.__schema__(:type, :item_id) do
       :integer ->
         model_id
 
-      _ ->
-        "#{model_id}"
+      UUID ->
+        if UUID.cast(model_id) == :error do
+          model_id
+          |> then(&:crypto.hash(:sha256, &1))
+          |> :binary.part(0, 16)
+          |> UUID.cast!()
+        else
+          model_id
+        end
+
+      _else ->
+        to_string(model_id)
     end
   end
 

priv/uuid_repo/migrations/20170525142613_create_items.exs

@@ -1,30 +1,38 @@
 defmodule PaperTrail.UUIDRepo.Migrations.CreateItems do
+  @moduledoc false
   use Ecto.Migration
 
   def change do
     create table(:items) do
-      add :item_id,      :binary_id, null: false, primary_key: true
-      add :title,        :string, null: false
+      add(:item_id, :binary_id, null: false, primary_key: true)
+      add(:title, :string, null: false)
 
       timestamps()
     end
 
     create table(:foo_items) do
-      add :title, :string, null: false
+      add(:title, :string, null: false)
 
       timestamps()
     end
 
     create table(:bar_items, primary_key: false) do
-      add :item_id, :string, primary_key: true
-      add :title, :string, null: false
+      add(:item_id, :string, primary_key: true)
+      add(:title, :string, null: false)
 
       timestamps()
     end
 
     create table(:uuid_items) do
-      add :item_id,      :uuid, null: false, primary_key: true
-      add :title,        :string, null: false
+      add(:item_id, :uuid, null: false, primary_key: true)
+      add(:title, :string, null: false)
+
+      timestamps()
+    end
+
+    create table(:composite_primary_keys_items, primary_key: false) do
+      add(:item_id, :uuid, primary_key: true)
+      add(:bar_id, :uuid, primary_key: true)
 
       timestamps()
     end

test/support/uuid_models.exs

@@ -1,4 +1,5 @@
 defmodule Product do
+  @moduledoc false
   use Ecto.Schema
 
   import Ecto.Changeset
@@ -18,7 +19,9 @@ defmodule Product do
 end
 
 defmodule Admin do
+  @moduledoc false
   use Ecto.Schema
+
   import Ecto.Changeset
 
   @primary_key {:id, :binary_id, autogenerate: true}
@@ -36,7 +39,9 @@ defmodule Admin do
 end
 
 defmodule Item do
+  @moduledoc false
   use Ecto.Schema
+
   import Ecto.Changeset
 
   @primary_key {:item_id, :binary_id, autogenerate: true}
@@ -54,7 +59,9 @@ defmodule Item do
 end
 
 defmodule UUIDItem do
+  @moduledoc false
   use Ecto.Schema
+
   import Ecto.Changeset
 
   @primary_key {:item_id, Ecto.UUID, autogenerate: true}
@@ -72,7 +79,9 @@ defmodule UUIDItem do
 end
 
 defmodule FooItem do
+  @moduledoc false
   use Ecto.Schema
+
   import Ecto.Changeset
 
   @primary_key {:id, :id, autogenerate: true}
@@ -90,7 +99,9 @@ defmodule FooItem do
 end
 
 defmodule BarItem do
+  @moduledoc false
   use Ecto.Schema
+
   import Ecto.Changeset
 
   @primary_key {:item_id, :string, autogenerate: false}
@@ -106,3 +117,24 @@ defmodule BarItem do
     |> validate_required([:item_id, :title])
   end
 end
+
+defmodule CompositePkItem do
+  @moduledoc false
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  @primary_key false
+  schema "composite_primary_keys_items" do
+    field(:item_id, Ecto.UUID, primary_key: true)
+    field(:bar_id, Ecto.UUID, primary_key: true)
+
+    timestamps()
+  end
+
+  def changeset(model, params \\ %{}) do
+    model
+    |> cast(params, [:item_id, :bar_id])
+    |> validate_required([:item_id, :bar_id])
+  end
+end

test/uuid/uuid_test.exs

@@ -4,6 +4,7 @@ defmodule PaperTrailTest.UUIDTest do
   import Ecto.Query
   import PaperTrail.RepoClient, only: [repo: 0]
 
+  alias Ecto.UUID
   alias PaperTrail.Version
 
   defmodule CustomPaperTrail do
@@ -86,6 +87,50 @@ defmodule PaperTrailTest.UUIDTest do
       assert version.item_id == uuid_item.item_id
     end
 
+    test "versioning models with composite primary keys" do
+      item_id1 = UUID.generate()
+      bar_id1 = UUID.generate()
+
+      item1 =
+        %CompositePkItem{}
+        |> CompositePkItem.changeset(%{item_id: item_id1, bar_id: bar_id1})
+        |> CustomPaperTrail.insert!()
+
+      version1 = Version |> last() |> repo().one
+
+      assert version1 == PaperTrail.get_version(item1)
+
+      assert %{
+               event: "insert",
+               item_changes: %{"bar_id" => ^bar_id1, "item_id" => ^item_id1},
+               item_id: version_id1,
+               item_type: "CompositePkItem"
+             } = version1
+
+      assert match?({:ok, _}, UUID.cast(version_id1))
+
+      item_id2 = UUID.generate()
+      bar_id2 = UUID.generate()
+
+      item2 =
+        %CompositePkItem{}
+        |> CompositePkItem.changeset(%{item_id: item_id2, bar_id: bar_id2})
+        |> CustomPaperTrail.insert!()
+
+      version2 = PaperTrail.get_version(item2)
+
+      assert %{
+               event: "insert",
+               item_changes: %{"bar_id" => ^bar_id2, "item_id" => ^item_id2},
+               item_id: version_id2,
+               item_type: "CompositePkItem"
+             } = version2
+
+      assert match?({:ok, _}, UUID.cast(version_id2))
+
+      assert version_id1 != version_id2
+    end
+
     test "test INTEGER primary key for item_type == :string" do
       if PaperTrail.Version.__schema__(:type, :item_id) == :string do
         item =