Sub-errors of arrays are nested only one level.

lib/formatters/ecto/changeset.ex

@@ -2,16 +2,10 @@ defmodule DeliriumTremex.Formatters.Ecto.Changeset do
   @spec format(error :: tuple()) :: Keyword.t()
   def format({key, [%{} | _] = errors} = _error) when is_list(errors) do
     errors = remove_empty_maps(errors)
-    human_key = humanize(key)
 
-    [
-      message: "#{human_key} errors",
-      key: key,
-      messages: nil,
-      full_messages: nil,
-      index: nil,
-      suberrors: Enum.map(errors, fn err -> format({key, err}) |> Enum.into(%{}) end)
-    ]
+    Enum.reduce(errors, [], fn err, acc ->
+      merge_suberror_kw_lists(acc, format({key, err}))
+    end)
   end
 
   def format({key, errors} = _error) when is_list(errors) do
@@ -72,6 +66,15 @@ defmodule DeliriumTremex.Formatters.Ecto.Changeset do
     Gettext.dgettext(DeliriumTremex.Gettext, "errors", msg, opts)
   end
 
+  defp merge_suberror_kw_lists(kw_list1, kw_list2) do
+    Keyword.merge(kw_list1, kw_list2, fn key, v1, v2 ->
+      case key do
+        :suberrors -> Enum.concat(v1, v2)
+        _ -> v1
+      end
+    end)
+  end
+
   defp remove_empty_maps(list_of_maps) do
     Enum.filter(list_of_maps, fn x -> map_size(x) > 0 end)
   end

test/formatters/ecto/changeset_test.exs

@@ -39,24 +39,22 @@ defmodule DeliriumTremex.Formatters.Ecto.ChangesetTest do
 
       formatted_data = Changeset.format(data)
 
-      assert formatted_data[:suberrors] == [
-               %{
-                 full_messages: nil,
-                 index: nil,
-                 key: :comments,
-                 message: "Comments errors",
-                 messages: nil,
-                 suberrors: [
-                   %{
-                     full_messages: ["User_id does not exist"],
-                     index: nil,
-                     key: :user_id,
-                     message: "User_id does not exist",
-                     messages: ["does not exist"],
-                     suberrors: nil
-                   }
-                 ]
-               }
+      assert formatted_data == [
+               message: "Comments errors",
+               key: :comments,
+               messages: nil,
+               full_messages: nil,
+               index: nil,
+               suberrors: [
+                 %{
+                   full_messages: ["User_id does not exist"],
+                   index: nil,
+                   key: :user_id,
+                   message: "User_id does not exist",
+                   messages: ["does not exist"],
+                   suberrors: nil
+                 }
+               ]
              ]
     end
   end