Merge pull request ZennerIoT#46 from GhostGroup/add-configurable-stru…

…ct-primitives

Add configurable struct primitives

.formatter.exs

@@ -1,4 +1,5 @@
 # Used by "mix format"
 [
+  import_deps: [:ecto, :ecto_sql],
   inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
 ]

README.md

@@ -83,6 +83,36 @@ config :ex_audit,
   ]
 ```
 
+Optionally, you can tell ExAudit to treat certain structs as primitives and not record internal changes for the 
+struct. Add these under the key `:primitive_structs` in your config. So for example, if you configured `Date` to be treated as a primitive:
+
+```elixir
+config :ex_audit,
+  ecto_repos: [ExAudit.Test.Repo],
+  version_schema: ExAudit.Test.Version,
+  tracked_schemas: [
+    ExAudit.Test.User,
+    ExAudit.Test.BlogPost,
+    ExAudit.Test.BlogPost.Section,
+    ExAudit.Test.Comment
+  ],
+  primitive_structs: [
+    Date
+  ]
+```
+
+then the patch would record the entire Date struct as a change:
+
+```elixir
+{:primitive_change, ~D[2000-01-01], ~D[2000-01-18]}
+```
+
+instead of descending into the struct to find the individual part that changed:
+
+```elixir
+{:changed, %{day: {:changed, {:primitive_change, 1, 18}}}}
+```
+
 ### Version Schema and Migration
 
 You need to copy the migration and the schema module for the versions table. This allows you to add custom fields

config/test.exs

@@ -19,4 +19,7 @@ config :ex_audit,
     ExAudit.Test.BlogPost,
     ExAudit.Test.BlogPost.Section,
     ExAudit.Test.Comment
+  ],
+  primitive_structs: [
+    Date
   ]

example/user.ex

@@ -7,6 +7,7 @@ defmodule ExAudit.Test.User do
   schema "users" do
     field :email, :string
     field :name, :string
+    field :birthday, :date
 
     field :transient_field, :integer
 
@@ -17,6 +18,6 @@ defmodule ExAudit.Test.User do
 
   def changeset(struct, params \\ %{}) do
     struct
-    |> cast(params, [:email, :name])
+    |> cast(params, [:email, :name, :birthday])
   end
-end
+end

lib/diff/diff.ex

@@ -31,6 +31,14 @@ defmodule ExAudit.Diff do
     :not_changed
   end
 
+  def diff(%{__struct__: a_struct} = a, %{__struct__: b_struct} = b) do
+    if primitive_struct?(a_struct) and primitive_struct?(b_struct) do
+      {:primitive_change, a, b}
+    else
+      diff(Map.from_struct(a), Map.from_struct(b))
+    end
+  end
+
   def diff(%{} = a, %{} = b) do
     all_keys =
       (Map.keys(a) ++ Map.keys(b))
@@ -129,4 +137,12 @@ defmodule ExAudit.Diff do
     |> Enum.reverse()
     |> Enum.map(&reverse/1)
   end
+
+  ## PRIVATE
+
+  defp primitive_struct?(type) do
+    primitive_structs = Application.get_env(:ex_audit, :primitive_structs, [])
+
+    type in primitive_structs
+  end
 end

priv/repo/migrations/20200519214139_add_birthday_to_user.exs

@@ -0,0 +1,9 @@
+defmodule ExAudit.Test.Repo.Migrations.AddBirthdayToUser do
+  use Ecto.Migration
+
+  def change do
+    alter table(:users) do
+      add :birthday, :date
+    end
+  end
+end

test/assoc_test.exs

@@ -3,7 +3,7 @@ defmodule AssocTest do
 
   import Ecto.Query
 
-  alias ExAudit.Test.{Repo, Version, BlogPost, Comment, Util, UserGroup}
+  alias ExAudit.Test.{Repo, Version, BlogPost, Comment, Util, User, UserGroup}
 
   test "comment lifecycle tracked" do
     user = Util.create_user()
@@ -29,6 +29,26 @@ defmodule AssocTest do
     assert actor_id == user.id
   end
 
+  test "structs configured as primitives are treated as primitives" do
+    {:ok, old_date} = Date.new(2000, 1, 1)
+    params = %{name: "Bob", email: "foo@bar.com", birthday: old_date}
+    changeset = User.changeset(%User{}, params)
+    {:ok, user} = Repo.insert(changeset)
+
+    new_date = Date.add(old_date, 17)
+    params = %{birthday: new_date}
+    changeset = User.changeset(user, params)
+    {:ok, user} = Repo.update(changeset)
+
+    [version | _] = Repo.history(user)
+
+    assert %{
+             patch: %{
+               birthday: {:changed, {:primitive_change, ^old_date, ^new_date}}
+             }
+           } = version
+  end
+
   test "should track cascading deletions (before they happen)" do
     user = Util.create_user()
 

test/diff_test.exs

@@ -74,4 +74,14 @@ defmodule DiffTest do
              baz: {:removed, 1}
            }
   end
+
+  test "structs configured as primitives are treated as primitives" do
+    val1 = Date.new(2020, 1, 1)
+    val2 = Date.new(2020, 2, 2)
+
+    a = %{foo: val1}
+    b = %{foo: val2}
+
+    assert %{foo: {:changed, {:primitive_change, val1, val2}}} == Diff.diff(a, b)
+  end
 end