From e4c56ce1af0c63c0524ffd8b002681d8dadda345 Mon Sep 17 00:00:00 2001
From: Rafael Scheffer <rafael@nash.io>
Date: Mon, 15 Feb 2021 10:48:52 -0300
Subject: [PATCH] Do not create version when there are no changes (#11)

---
 lib/paper_trail.ex             | 21 +++++++++++----------
 lib/paper_trail/multi.ex       | 12 +++++++++---
 test/paper_trail/base_test.exs | 23 +++++++++++++++++++++++
 3 files changed, 43 insertions(+), 13 deletions(-)

diff --git a/lib/paper_trail.ex b/lib/paper_trail.ex
index 2dec0e10..09d36092 100644
--- a/lib/paper_trail.ex
+++ b/lib/paper_trail.ex
@@ -1,6 +1,7 @@
 defmodule PaperTrail do
   import Ecto.Changeset
 
+  alias Ecto.Changeset
   alias PaperTrail.Multi
   alias PaperTrail.RepoClient
   alias PaperTrail.Serializer
@@ -32,16 +33,16 @@ defmodule PaperTrail do
               returning: boolean()
             ]
 
-  @type result :: {:ok, Ecto.Schema.t()} | {:error, Ecto.Changeset.t()}
+  @type result :: {:ok, Ecto.Schema.t()} | {:error, Changeset.t()}
   @type all_result :: {integer, nil | [any]}
 
-  @callback insert(Ecto.Changeset.t(), options) :: result
-  @callback insert!(Ecto.Changeset.t(), options) :: Ecto.Schema.t()
-  @callback update(Ecto.Changeset.t(), options) :: result
-  @callback update!(Ecto.Changeset.t(), options) :: Ecto.Schema.t()
+  @callback insert(Changeset.t(), options) :: result
+  @callback insert!(Changeset.t(), options) :: Ecto.Schema.t()
+  @callback update(Changeset.t(), options) :: result
+  @callback update!(Changeset.t(), options) :: Ecto.Schema.t()
   @callback update_all(queryable, updates, options) :: all_result
-  @callback delete(Ecto.Changeset.t(), options) :: result
-  @callback delete!(Ecto.Changeset.t(), options) :: Ecto.Schema.t()
+  @callback delete(Changeset.t(), options) :: result
+  @callback delete!(Changeset.t(), options) :: Ecto.Schema.t()
 
   @callback get_version(Ecto.Schema.t()) :: Ecto.Query.t()
   @callback get_version(module, any) :: Ecto.Query.t()
@@ -172,7 +173,7 @@ defmodule PaperTrail do
   @doc """
   Inserts a record to the database with a related version insertion in one transaction
   """
-  @spec insert(Ecto.Changeset.t(), options) :: result
+  @spec insert(Changeset.t(), options) :: result
   def insert(changeset, options \\ []) do
     Multi.new()
     |> Multi.insert(changeset, options)
@@ -230,7 +231,7 @@ defmodule PaperTrail do
   @doc """
   Updates a record from the database with a related version insertion in one transaction
   """
-  @spec update(Ecto.Changeset.t(), options) :: result
+  @spec update(Changeset.t(), options) :: result
   def update(changeset, options \\ []) do
     Multi.new()
     |> Multi.update(changeset, options)
@@ -292,7 +293,7 @@ defmodule PaperTrail do
   @doc """
   Deletes a record from the database with a related version insertion in one transaction
   """
-  @spec delete(Ecto.Changeset.t(), options) :: result
+  @spec delete(Changeset.t(), options) :: result
   def delete(struct, options \\ []) do
     Multi.new()
     |> Multi.delete(struct, options)
diff --git a/lib/paper_trail/multi.ex b/lib/paper_trail/multi.ex
index e4ae6548..6a5bf64e 100644
--- a/lib/paper_trail/multi.ex
+++ b/lib/paper_trail/multi.ex
@@ -1,17 +1,18 @@
 defmodule PaperTrail.Multi do
   import Ecto.Changeset
 
+  alias Ecto.Changeset
   alias PaperTrail
   alias PaperTrail.Version
   alias PaperTrail.RepoClient
   alias PaperTrail.Serializer
 
   @type multi :: Ecto.Multi.t()
-  @type changeset :: Ecto.Changeset.t()
+  @type changeset :: Changeset.t()
   @type options :: PaperTrail.options()
   @type queryable :: PaperTrail.queryable()
   @type updates :: PaperTrail.updates()
-  @type struct_or_changeset :: Ecto.Schema.t() | Ecto.Changeset.t()
+  @type struct_or_changeset :: Ecto.Schema.t() | Changeset.t()
   @type result ::
           {:ok, any()}
           | {:error, any()}
@@ -133,7 +134,12 @@ defmodule PaperTrail.Multi do
         |> Ecto.Multi.update(model_key, changeset)
         |> Ecto.Multi.run(version_key, fn repo, _changes ->
           version = make_version_struct(%{event: "update"}, changeset, options)
-          repo.insert(version)
+
+          if changeset.changes == %{} do
+            {:ok, nil}
+          else
+            repo.insert(version)
+          end
         end)
     end
   end
diff --git a/test/paper_trail/base_test.exs b/test/paper_trail/base_test.exs
index ef6eded7..025c3667 100644
--- a/test/paper_trail/base_test.exs
+++ b/test/paper_trail/base_test.exs
@@ -167,6 +167,29 @@ defmodule PaperTrailTest do
     assert company == first(Company, :id) |> @repo.one |> serialize
   end
 
+  test "do not create version if there're no changes" do
+    {:ok, insert_result} = create_company_with_version()
+
+    {:ok, result} =
+      update_company_with_version(
+        insert_result[:model],
+        %{}
+      )
+
+    company_count = Company.count()
+    version_count = Version.count()
+
+    company = result[:model] |> serialize
+    version = result[:version]
+
+    assert Map.keys(result) == [:model, :version]
+    assert company_count == 1
+    assert version_count == 1
+
+    assert company == insert_result[:model] |> serialize
+    assert version == nil
+  end
+
   test "updating a company with originator[user] creates a correct company version" do
     user = create_user()
     {:ok, insert_result} = create_company_with_version()