add test to reproduce errors

test/form_test.exs

@@ -4,7 +4,7 @@ defmodule AshPhoenix.FormTest do
   import ExUnit.CaptureLog
 
   alias AshPhoenix.Form
-  alias AshPhoenix.Test.{Api, Comment, OtherApi, Post, PostWithDefault}
+  alias AshPhoenix.Test.{Api, Author, Comment, OtherApi, Post, PostWithDefault}
   alias Phoenix.HTML.FormData
 
   describe "validate_opts" do
@@ -772,6 +772,45 @@ defmodule AshPhoenix.FormTest do
       assert [nested_form] = inputs_for(form, :post)
       assert nested_form.errors == [{:text, {"is required", []}}]
     end
+
+    test "errors with a path are propagated down to the appropirate nested form" do
+      author = %Author{
+        email: "[email protected]"
+      }
+
+      form =
+        author
+        |> Form.for_update(:update_with_embedded_argument, api: Api, forms: [auto?: true])
+        |> Form.add_form(:embedded_argument, params: %{})
+        |> Form.validate(%{"embedded_argument" => %{"value" => "[email protected]"}})
+        |> form_for("action")
+        [nested_form] = inputs_for(form, :embedded_argument)
+
+
+        # This is the top level error with a path to the nest form.
+        assert [
+          %Ash.Error.Changes.InvalidArgument{
+            field: :value,
+            message: "must match email",
+            value: "[email protected]",
+            path: [:embedded_argument],
+            class: :invalid
+          }
+        ] = form.source.source.errors
+        assert form.errors == []
+
+        # This is the error on the nested form.
+        assert [
+          %Ash.Error.Changes.InvalidArgument{
+            field: :value,
+            message: "must match email",
+            value: "[email protected]",
+            path: [],
+            class: :invalid
+          }
+        ] = nested_form.source.source.errors
+        assert nested_form.errors == [{:value, {"must match email", []}}]
+    end
   end
 
   describe "data" do

test/support/resources/author.ex

@@ -13,6 +13,14 @@ defmodule AshPhoenix.Test.Author do
 
   actions do
     defaults([:create, :read, :update])
+
+    update :update_with_embedded_argument do
+      # This an empty change, just so test how we handle errors on embedded arguments
+      accept []
+      argument :embedded_argument, AshPhoenix.Test.EmbeddedArgument, allow_nil?: false
+
+      validate { AshPhoenix.Test.ValidateEmbeddedArgument, [] }
+    end
   end
 
   relationships do

test/support/resources/embedded_argument.ex

@@ -0,0 +1,8 @@
+defmodule AshPhoenix.Test.EmbeddedArgument do
+  @moduledoc false
+  use Ash.Resource, data_layer: :embedded
+
+  attributes do
+    attribute :value, :string
+  end
+end

test/support/validations/validate_embedded_argument.ex

@@ -0,0 +1,44 @@
+defmodule AshPhoenix.Test.ValidateEmbeddedArgument do
+  @moduledoc """
+  This is a contrived example, but we want to validate one or more arguments' attributes
+  against an attribute on the parent resource and then put an error on the
+  changeset that will get propogated down to the nest form for the embedded argument.
+  """
+
+  use Ash.Resource.Validation
+
+  # This is the name of our embedded argument
+  @embedded_argument :embedded_argument
+
+  # This is the name of the attribute on the embedded argument
+  @embedded_attribute :value
+
+  @impl true
+  def validate(changeset, _opts) do
+    case Ash.Changeset.get_argument(changeset, @embedded_argument) do
+      nil ->
+        :ok
+
+      argument ->
+        apply_validation(changeset, argument)
+    end
+  end
+
+  def apply_validation(changeset, argument) do
+    email = Ash.Changeset.get_attribute(changeset, :email)
+    value = Map.get(argument, @embedded_attribute)
+
+    if value == email do
+      :ok
+    else
+      {:error,
+        Ash.Error.Changes.InvalidArgument.exception(
+          field: @embedded_attribute,
+          message: "must match email",
+          value: value,
+          path: [@embedded_argument]
+        )
+      }
+    end
+  end
+end