fix: handling struct nested values properly

apps/one_piece_commanded/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+## v0.21.1 - 2024-11-26
+
+- Fix casting structs in `OnePiece.Commanded.ValueObject`. Related to https://github.com/elixir-ecto/ecto/issues/4168
+
 ## v0.21.0 - 2024-11-02
 
 - Added `OnePiece.Commanded.Enum` module.

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

@@ -140,33 +140,27 @@ defmodule OnePiece.Commanded.ValueObject do
 
     changeset =
       message
-      |> Changeset.cast(attrs, fields -- embeds)
+      |> Changeset.cast(from_struct(attrs), fields -- embeds)
       |> Changeset.validate_required(struct_module.__enforced_keys__() -- embeds)
 
     Enum.reduce(
       embeds,
       changeset,
-      &cast_embed(&1, &2, struct_module, attrs)
+      &cast_embed(&1, &2, struct_module)
     )
   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
+  defp cast_embed(field, changeset, struct_module) do
+    Changeset.cast_embed(changeset, field, required: struct_module.__enforced_keys__?(field))
+  end
+
+  defp from_struct(value) when is_struct(value) do
+    # https://github.com/elixir-ecto/ecto/issues/4168
+    Map.from_struct(value)
   end
 
+  defp from_struct(value), do: value
+
   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 "0.21.0"
+  @version "0.21.1"
   @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

@@ -21,9 +21,17 @@ defmodule OnePiece.Commanded.ValueObjectTest do
                TestSupport.MessageThree.new(%{target: %{title: "Hello, World!"}})
     end
 
-    test "bypass casting structs" do
+    test "casting structs" do
       assert {:ok, %TestSupport.MessageThree{target: %TestSupport.MessageOne{title: "Hello, World!"}}} =
                TestSupport.MessageThree.new(%{target: %TestSupport.MessageOne{title: "Hello, World!"}})
+
+      assert {:ok,
+              %TestSupport.MessageFour{
+                targets: [%TestSupport.MessageThree{target: %TestSupport.MessageOne{title: "Hello, World!"}}]
+              }} =
+               TestSupport.MessageFour.new(%{
+                 targets: [%TestSupport.MessageThree{target: %TestSupport.MessageOne{title: "Hello, World!"}}]
+               })
     end
 
     test "validates casting embed fields with a wrong value" do

apps/one_piece_commanded/test/support/test_support.ex

@@ -43,6 +43,17 @@ defmodule TestSupport do
     end
   end
 
+  defmodule MessageFour do
+    @moduledoc false
+
+    use OnePiece.Commanded.ValueObject
+
+    @enforce_keys [:targets]
+    embedded_schema do
+      embeds_many(:targets, MessageThree)
+    end
+  end
+
   defmodule MyEntityOne do
     @moduledoc false