Sanitize_image_filename.rb

# return a sanitized version of the image filename
# (remove spaces, etc.) and then determine position
# based on filename (eg. 1.jpg, 2.jpg)

def sanitize_and_position_photo
  filename = self.image_file_name
  ext = File.extname(filename)
  just_filename = File.basename(filename, ext)
  unless just_filename.to_i == 0
    self.position = just_filename.to_i
  end
  self.image_file_name = just_filename.gsub(/\W+/,'_') + ext
end