title: Getting "NoMethodError (undefined method `extension'..." when trying to run in production on heroku
body: <p>HI my app works fine locally when using :file but once i'ts pushed up to heroku and using S3 I get this error when trying to upload. It looks to be a porblem with the def filename method.</p>
  
  <p>The heroku logs show:</p>
  
  <pre><code> NoMethodError (undefined method `extension' for #&lt;CarrierWave::Storage::S3::File:0x00000006316a90&gt;):
   app/uploaders/image_uploader.rb:53:in `filename'
  </code></pre>
  
  <p>This is how I have filename defined in my uploader:</p>
  
  <pre><code>  def filename
         "image.#{model.image.file.extension}" if original_filename
       end
  </code></pre>
  
  <p>How can i fix this? Thanks!</p>