Get redirect of a URL in Ruby

Question

According to Facebook graph API we can request a user profile picture with this (example):

https://graph.facebook.com/1489686594/picture

Bu

Answer 1

You've got HTTPS URLs there, so you will handle that...

require 'net/http'
require 'net/https' if RUBY_VERSION < '1.9'
require 'uri'

u = URI.parse('https://graph.facebook.com/1489686594/picture')

h = Net::HTTP.new u.host, u.port
h.use_ssl = u.scheme == 'https'

head = h.start do |ua|
  ua.head u.path
end

puts head['location']

Answer 2

You can check the response status code and get the final URL recursively using something like get_final_redirect_url method:

  require 'net/http'

  def get_final_redirect_url(url, limit = 10)
    uri = URI.parse(url)
    response = ::Net::HTTP.get_response(uri)
    if response.class == Net::HTTPOK
      return uri
    else
      redirect_location = response['location']
      location_uri = URI.parse(redirect_location)
      if location_uri.host.nil?
        redirect_location = uri.scheme + '://' + uri.host + redirect_location
      end
      warn "redirected to #{redirect_location}"
      get_final_redirect_url(redirect_location, limit - 1)
    end
  end

I was facing the same issue. I solved it and built a gem final_redirect_url around it, so that everyone can benefit from it.

You can find the details on uses here.

Answer 3

Yeah, "Location" response header tell you the actual image URL.

However, if you use the picture as the user's profile image on your site, I recommend you to use "https://graph.facebook.com/:user_id/picture" style URL instead of actual image URL. Otherwise, your users will see lots of "not found" images, or outdated profile images in the future.

You just put "https://graph.facebook.com/:user_id/picture" as the "src" attribute of "img" tag. They browser gets the updated image of the user.

ps. I have such troubles on my site with Twitter & Yahoo! OpenID now..

Answer 4

You can use Net::Http and read the Location: header from the response

require 'net/http'
require 'uri'

url = URI.parse('http://www.example.com/index.html')
res = Net::HTTP.start(url.host, url.port) {|http|
  http.get('/index.html')
}
res['location']

Answer 5

I know this is an old question, but I'll add this answer for posterity:

Most of the solutions I've seen only follow a single redirect. In my case, I had to follow multiple redirects to get the actual final destination URL. I used Curl (via the Curb gem) like so:

result = Curl::Easy.perform(url) do |curl|
  curl.head = true
  curl.follow_location = true
end
result.last_effective_url

Answer 6

If you want a solution that:

• does not use gems
• follows all redirects
• works also with url-shortening services

require 'net/http'
require 'uri'

def follow_redirections(url)   
  response = Net::HTTP.get_response(URI(url))
  until response['location'].nil?
    response = Net::HTTP.get_response(URI(response['location']))
  end
  response.uri.to_s
end

# EXAMPLE USAGE
follow_redirections("https://graph.facebook.com/1489686594/picture") 
# => https://static.xx.fbcdn.net/rsrc.php/v3/yo/r/UlIqmHJn-SK.gif