feat: allow aldeady casted structs (#63)

.tool-versions

@@ -1,2 +1,2 @@
-elixir 1.14.2
-erlang 25.2
+elixir 1.14.3
+erlang 25.3

apps/one_piece_commanded/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+## v0.15.2 - 2023-03-14
+
+- Fix casting already cast structs in `OnePiece.Commanded.ValueObject`.
+
 ## v0.15.1 - 2022-12-24
 
 - Fix `OnePiece.Commanded.Event` and ``OnePiece.Commanded.Entity` to extend from `OnePiece.Commanded.ValueObject`.

apps/one_piece_commanded/lib/one_piece/commanded/value_object.ex

@@ -110,20 +110,37 @@ defmodule OnePiece.Commanded.ValueObject do
 
   def __changeset__(%struct_module{} = message, attrs) do
     embeds = struct_module.__schema__(:embeds)
-    allowed = struct_module.__schema__(:fields) -- embeds
+    fields = struct_module.__schema__(:fields)
 
     changeset =
       message
-      |> Changeset.cast(attrs, allowed)
+      |> Changeset.cast(attrs, fields -- embeds)
       |> Changeset.validate_required(struct_module.__enforced_keys__() -- embeds)
 
     Enum.reduce(
       embeds,
       changeset,
-      &Changeset.cast_embed(&2, &1, required: struct_module.__enforced_keys__?(&1))
+      &cast_embed(&1, &2, struct_module, attrs)
     )
   end
 
+  defp cast_embed(field, changeset, struct_module, attrs) do
+    case is_struct(attrs[field]) do
+      false ->
+        Changeset.cast_embed(changeset, field, required: struct_module.__enforced_keys__?(field))
+
+      true ->
+        # credo:disable-for-next-line Credo.Check.Design.TagTODO
+        # TODO: Validate that the struct is of the correct type.
+        #   It may be the case that you passed a completely different struct as the value. We could `cast_embed`
+        #   always and fix the `Changeset.cast(attrs, fields -- embeds)` by converting the `attrs` into a map. But it
+        #   would be a bit more expensive since it will run the casting for a field that was already casted.
+        #   Checking the struct types MAY be enough but taking into consideration `embeds_many` could complicated
+        #   things. For now, we'll just assume that the user knows what they're doing.
+        Changeset.put_change(changeset, field, attrs[field])
+    end
+  end
+
   defp apply_changeset(struct_module, attrs) do
     struct(struct_module)
     |> struct_module.changeset(attrs)

apps/one_piece_commanded/mix.exs

@@ -2,7 +2,7 @@ defmodule OnePiece.Commanded.MixProject do
   use Mix.Project
 
   @app :one_piece_commanded
-  @version "0.15.1"
+  @version "0.15.2"
   @elixir_version "~> 1.13"
   @source_url "https://github.com/straw-hat-team/beam-monorepo"
 

apps/one_piece_commanded/test/one_piece/commanded/value_object_test.exs

@@ -21,6 +21,11 @@ defmodule OnePiece.Commanded.ValueObjectTest do
                TestSupport.MessageThree.new(%{target: %{title: "Hello, World!"}})
     end
 
+    test "bypass casting structs" do
+      assert {:ok, %TestSupport.MessageThree{target: %TestSupport.MessageOne{title: "Hello, World!"}}} =
+               TestSupport.MessageThree.new(%{target: %TestSupport.MessageOne{title: "Hello, World!"}})
+    end
+
     test "validates casting embed fields with a wrong value" do
       {:error, changeset} = TestSupport.MessageThree.new(%{target: "a wrong value"})
       assert %{target: ["is invalid"]} = TestSupport.errors_on(changeset)