Question

Is it possible to call or instantiate OmniAuth given that a authorization code for Facebook? Using authenticated referalls Facebook will append a ?code=ABC... to the URL.

Facebook documentation states that after receiving the authorization code one should then request the access token, however upon browsing through the omniauth-facebook gem this code already seems to exist (line 64).

My reason for wanting to integrate with OmniAuth is to avoid duplicating the code just to get authenticated referrals working. Thanks!

Answer 1

After looking into this two immediate options are available:

1. Redirect to the Facebook OAuth path.

2. Use the passsed in code to manually grab all the OAuth info from Facebook.

Here was some code that does some of the OAuth steps given a code.

require 'httparty'
require 'fb_graph'

def self.get_access_token(code, redirect_uri)
  redirect_uri = remove_code_from_redirect_uri(redirect_uri)

  response = HTTParty.get(ACCESS_TOKEN_URL, query: { code: code, client_id: FB_APP_ID, client_secret: FB_APP_SECRET, redirect_uri: redirect_uri })
  return unless response.success?

  results = Hashie::Mash.new
  response.body.split('&').each do |param| key, value = param.split('='); results[key] = value; end
  return results.access_token
end

def self.get_auth(access_token)
  user = FbGraph::User.me(access_token).fetch

  results = Hashie::Mash.new
  results['info'] = Hashie::Mash.new
  results['credentials'] = Hashie::Mash.new

  results['uid'] = user.identifier

  results['info']['name'] = user.name
  results['info']['email'] = user.email
  results['info']['image'] = user.picture
  results['info']['nickname'] = user.username

  results['credentials']['token'] = access_token

  return results
end

private

def self.remove_code_from_redirect_uri(redirect_uri)
  url, params = redirect_uri.split("?")
  params = params.split('&').inject({}) { |hash, param| k, v = param.split('='); hash[k] = v; hash }
  params.delete("code")
  url + '?' + CGI::unescape(params.to_query)
end