How to: Do conditional processing

If you want to hold both images and regular files as attachments to a model, additional processing (i.e. creating a thumbnail) can be attached only to images.

Here's the example code to create thumbnails when the uploaded file is an image:

version :thumb, :if => :image? do
  process :resize_to_limit => [200, 200]
end

protected

def image?(new_file)
  new_file.content_type.include? 'image'
end