fix: keep data from source_changeset

Author: nduitz

lib/polymorphic_embed/html/helpers.ex

@@ -49,45 +49,68 @@ if Code.ensure_loaded?(Phoenix.HTML) && Code.ensure_loaded?(Phoenix.HTML.Form) d
       form.source.data.__struct__
     end
 
-    def to_form(%{action: parent_action} = source_changeset, form, field, options) do
+    def to_form(source_changeset, %{action: parent_action} = form, field, options) do
       id = to_string(form.id <> "_#{field}")
       name = to_string(form.name <> "[#{field}]")
 
       params = Map.get(source_changeset.params || %{}, to_string(field), %{}) |> List.wrap()
 
       struct = Ecto.Changeset.apply_changes(source_changeset)
 
-      list_data =
-        case Map.get(struct, field) do
-          nil ->
-            type = Keyword.get(options, :polymorphic_type, get_polymorphic_type(form, field))
-            module = PolymorphicEmbed.get_polymorphic_module(struct.__struct__, field, type)
-            if module, do: [struct(module)], else: []
+      Map.get(source_changeset.changes, field)
+      |> case do
+        nil ->
+          case Map.get(struct, field) do
+            nil ->
+              type = Keyword.get(options, :polymorphic_type, get_polymorphic_type(form, field))
+              module = PolymorphicEmbed.get_polymorphic_module(struct.__struct__, field, type)
+              if module, do: [struct(module)], else: []
 
-          data ->
-            List.wrap(data)
-        end
+            data ->
+              List.wrap(data)
+          end
 
-      list_data
+        data when is_list(data) ->
+          data
+
+        data ->
+          List.wrap(data)
+      end
       |> Enum.with_index()
-      |> Enum.map(fn {data, i} ->
-        params = Enum.at(params, i) || %{}
+      |> Enum.map(fn
+        {%Ecto.Changeset{} = changeset, i} ->
+          params = changeset.params || %{}
+          errors = get_errors(changeset)
+
+          %{changeset: changeset, params: params, errors: errors, index: i}
+
+        {data, i} ->
+          params = Enum.at(params, i) || %{}
 
-        %Ecto.Changeset{} =
           changeset =
-          data
-          |> Ecto.Changeset.change()
-          |> apply_action(parent_action)
+            data
+            |> Ecto.Changeset.change()
+            |> apply_action(parent_action)
 
-        errors = get_errors(changeset)
+          errors = get_errors(changeset)
 
-        changeset = %Ecto.Changeset{
-          changeset
-          | action: parent_action,
-            params: params,
-            errors: errors,
-            valid?: errors == []
-        }
+          changeset = %{
+            changeset
+            | action: parent_action,
+              params: params,
+              errors: errors,
+              valid?: errors == []
+          }
+
+          %{changeset: changeset, params: params, errors: errors, index: i}
+      end)
+      |> Enum.map(fn prepared_data ->
+        %{
+          changeset: changeset,
+          params: params,
+          errors: errors,
+          index: i
+        } = prepared_data
 
         %schema{} = source_changeset.data
 
@@ -107,7 +130,7 @@ if Code.ensure_loaded?(Phoenix.HTML) && Code.ensure_loaded?(Phoenix.HTML.Form) d
           name: if(array?, do: name <> "[" <> index_string <> "]", else: name),
           index: if(array?, do: i),
           errors: errors,
-          data: data,
+          data: changeset.data,
           action: parent_action,
           params: params,
           hidden: [{type_field_name, to_string(type)}],