Paperclip interpolations and attachment styles sample

paperclip_settings.rb

class Model < ActiveRecord::Base
  # Paperclip
  has_attached_file :attachment,
                    :styles => {:large => "640x480#", :thumb => "320x240#"},
                    :path => "/:class/:attachment/:style/:uniq_file_name.:extension"

  validates_attachment_size :attachment, :less_than => 0..512.kilobytes
  validates_attachment_content_type :attachment, :content_type => %w(image/jpeg image/jpg image/png application/pdf)

  Paperclip.interpolates :uniq_file_name do |attachment, style|
    attachment.instance.uniq_file_name
  end

  def uniq_file_name
    Digest::SHA1.hexdigest(id.to_s)
  end
end