refactor extracting data and preparing changeset

Author: nduitz

lib/polymorphic_embed/html/helpers.ex

@@ -57,53 +57,9 @@ if Code.ensure_loaded?(Phoenix.HTML) && Code.ensure_loaded?(Phoenix.HTML.Form) d
 
       struct = Ecto.Changeset.apply_changes(source_changeset)
 
-      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 when is_list(data) ->
-          data
-
-        data ->
-          List.wrap(data)
-      end
+      resolve_field_data(source_changeset, struct, form, field, options)
       |> Enum.with_index()
-      |> 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) || %{}
-
-          changeset =
-            data
-            |> Ecto.Changeset.change()
-            |> apply_action(parent_action)
-
-          errors = get_errors(changeset)
-
-          changeset = %{
-            changeset
-            | action: parent_action,
-              params: params,
-              errors: errors,
-              valid?: errors == []
-          }
-
-          %{changeset: changeset, params: params, errors: errors, index: i}
-      end)
+      |> Enum.map(&prepare_changeset(&1, params, parent_action))
       |> Enum.map(fn prepared_data ->
         %{
           changeset: changeset,
@@ -139,6 +95,52 @@ if Code.ensure_loaded?(Phoenix.HTML) && Code.ensure_loaded?(Phoenix.HTML.Form) d
       end)
     end
 
+    defp resolve_field_data(source_changeset, struct, form, field, options) do
+      case Map.get(source_changeset.changes, field) 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
+    end
+
+    defp prepare_changeset({%Ecto.Changeset{} = changeset, i}, _params, _parent_action) do
+      params = changeset.params || %{}
+      errors = get_errors(changeset)
+
+      %{changeset: changeset, params: params, errors: errors, index: i}
+    end
+
+    defp prepare_changeset({data, i}, params, parent_action) do
+      params = Enum.at(params, i) || %{}
+
+      changeset =
+        data
+        |> Ecto.Changeset.change()
+        |> apply_action(parent_action)
+
+      errors = get_errors(changeset)
+
+      changeset = %Ecto.Changeset{
+        changeset
+        | action: parent_action,
+          params: params,
+          errors: errors,
+          valid?: errors == []
+      }
+
+      %{changeset: changeset, params: params, errors: errors, index: i}
+    end
+
     # If the parent changeset had no action, we need to remove the action
     # from children changeset so we ignore all errors accordingly.
     defp apply_action(changeset, nil), do: %{changeset | action: nil}