FEATURE: Show user fields when the user is signing up

app/serializers/user_serializer.rb

@@ -46,7 +46,8 @@ class UserSerializer < BasicUserSerializer
              :notification_count,
              :has_title_badges,
              :edit_history_public,
-             :custom_fields
+             :custom_fields,
+             :user_fields
 
   has_one :invited_by, embed: :object, serializer: BasicUserSerializer
   has_many :custom_groups, embed: :object, serializer: BasicGroupSerializer
@@ -253,6 +254,14 @@ class UserSerializer < BasicUserSerializer
     can_edit && !SiteSetting.edit_history_visible_to_public
   end
 
+  def user_fields
+    object.user_fields
+  end
+
+  def include_user_fields?
+    user_fields.present?
+  end
+
   def custom_fields
     fields = nil