Protocol relative URLs in Paperclip

paperclip.rb

# config/initializers/paperclip.rb

require 'paperclip/protocol_relative_url_support'
Paperclip::Attachment.send :include, Paperclip::ProtocolRelativeURLSupport

protocol_relative_url_support.rb

# lib/paperclip/protocol_relative_url_support.rb

module Paperclip
  module ProtocolRelativeURLSupport
    def self.included(base)
      base.alias_method_chain :url, :protocol_relative
    end

    def url_with_protocol_relative(style_name = default_style, options = {})
      u = url_without_protocol_relative(style_name, options)
      if options and options[:protocol_relative]
        u.gsub(/^https?:/, '')
      else
        u
      end
    end
  end
end

test.rb

# get a protocol relative URL like this
product.image.attachment.url(:original, protocol_relative: true)