gistfile1.txt

class Photo
  def photo_filename= filename
    if (self.photo = File.read(filename) rescue nil)
      save!
    end
  end
end

# ...

task :photos => :environment do
    Photo.find_each(:conditions => {:photo_file_name => nil}) { |p|
      p.photo_filename = "../flygfotohistoria_old/public/assets/motifs/original/#{p.old_id}.jpg"
      puts p.id
    }
end