Rails4 demodulizeメソッドが使えない？

demodulizeメソッドが使えなくなった？下記エラー発生

2015/11/20 18:02:16 [INFO] ::   Rendered pogepoge/_select_hoge.html.erb (317.7ms)

2015/11/20 18:02:16 [ERROR] ::  アプリケーションエラー。
, undefined method `demodulize' for #

2015/11/20 18:02:16 [INFO] ::

        /poge/hoge/workspace/version/app/pogeapp/lib/my_active_resource/base.rb:291:in `demodulized_underscore_name'

        /poge/hoge/workspace/version/app/pogeapp/app/views/pogepoge/_select_hoge.html.erb:55:in `block (5 levels) in _pogepoge__select_hoge_html_erb___2093292265898603831_70005643233100'

        /poge/hoge/workspace/version/app/pogeapp/app/helpers/application_helper.rb:1826:in `show_table_if_exists'

        /poge/hoge/workspace/version/app/pogeapp/app/views/pogepoge/_select_hoge.html.erb:54:in `block (4 levels) in _pogepoge__select_hoge_html_erb___2093292265898603831_70005643233100'

        /poge/hoge/workspace/version/app/pogeapp/app/helpers/application_helper.rb:1638:in `block (3 levels) in widget_box_frame'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:38:in `block in capture'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:200:in `with_output_buffer'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:38:in `capture'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/tag_helper.rb:94:in `content_tag'

        /poge/hoge/workspace/version/app/pogeapp/app/helpers/application_helper.rb:1637:in `block (2 levels) in widget_box_frame'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:38:in `block in capture'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:200:in `with_output_buffer'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:38:in `capture'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/tag_helper.rb:94:in `content_tag'

        /poge/hoge/workspace/version/app/pogeapp/app/helpers/application_helper.rb:1636:in `block in widget_box_frame'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:38:in `block in capture'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:200:in `with_output_buffer'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/capture_helper.rb:38:in `capture'

        /poge/hoge/.rbenv/versions/2.2.3/gemsets/4.0/gems/actionpack-4.0.13/lib/action_view/helpers/tag_helper.rb:94:in `content_tag'

• 使い方？ requireしても使えない…Stringクラスに変換すると使えるようになる
• rails4からはStringクラスでしか使えない？

     def self.demodulized_hogehoge_name
-      self.model_name.demodulize.underscore
+      self.model_name.to_s.demodulize.underscore
     end