get image from link(use paperclip)

image_from_url.rb

require "open-uri"
require 'tempfile'

def image_from_url(url)
  ext = File.extname(url)
  filename = File.basename(url, ext)

  temp = Tempfile.new([filename, ext])
  str = open(url).read
  temp.write(str)

  File.open(temp.path) do |f|
    self.image = f 
    self.save
  end
end