Save remote file using Paperclip

require 'open-uri'
require 'net/http'

# example with a Flickr image
require 'flickraw'
FlickRaw.api_key=FLICKR_API_KEY
FlickRaw.shared_secret=FLICKR_SECRET

# grab the most interesting unrestricted image from Flickr
photos = flickr.photos.search :per_page => 1, :page => 1, :content_type => 1, :license => 7, :sort => 'interestingness-desc'

# form the url to the image
image_url = "http://farm#{photo.farm}.static.flickr.com/#{photo.server}/#{photo.id}_#{photo.secret}_s.jpg"

# open the image to a file
file = open image_url

# find a user
user = User.find :first

# set his favorite photo, where favorite_photo is
#  already setup in the user model as
#   has_attached_file :favorite_photo
user.favorite_photo = file
user.save