Deprecated offline_access on facebook with RoR

Question

We have a problem in our RoR app. We are using a facebook authentication with omniauth, and searching the user friends with Koala. But lately, when we try to show a friend photo, we got this error:

Koala::Facebook::APIError in Homes#show

Showing /home/daniel/Homes/app/views/shared/_event.html.erb where line #19 raised:

OAuthException: Error validating access token: Session has expired at unix time 1328727600. The current unix time is 1328802133.
Extracted source (around line #19):

16:     <img src="../assets/friends-icon.png" alt="User  profile apicture" height="33" width="43">
17:         <% if current_user %>
18:           <% event.friends_in_event(@person).each do |f| %>
19:             <%= link_to(image_tag(f.fb_picture, :size => "43x33"), person_path(f.id)) %>
20:           <% end %>
21:         <% end %>
22:       </div>

The authentication works good, but facebook has already deprecated the offline_access option, that was working good, but now, we have this issue. is It any way to extends the access_token?, or are there another solution?.

This is our omniauth.rb

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :facebook, ENV['FB_KEY'], ENV['FB_SECRET'], 
  { :scope => 'email,offline_access,user_photos,publish_stream',
    :client_options => { :ssl => { :ca_path => "/etc/ssl/certs" } } }
end

And our koala.rb

Koala.http_service.http_options = {
  :ssl => { :ca_path => "/etc/ssl/certs" }
}

Thanks in advance.

Answer 1

There are 2 solutions to this problem:

• Extend the user's access token:
  • As per this article on the Facebook docs, you may request a 60-day extension on a user's access token. However, if the user does not return within that period, this method won't help you.
  • You can find a PHP code snippet to do this at this StackOverflow question.
    1. To do this, send a post to this API endpoint: https://graph.facebook.com/oauth/access_token?client_id=APP_ID&client_secret=APP_SECRET&grant_type=fb_exchange_token&fb_exchange_token=EXISTING_ACCESS_TOKEN

---

• Catch the OAuthException and request a new access token:
  • Facebook provides a PHP code snippet outlining this solution on their dev blog.
  • Basically, you follow these steps:
    1. Make a call to the graph with the user's current access_token.
    2. If the call succeeds, the access_token is fine. If it throws an OAuthException, redirect the user to https://www.facebook.com/dialog/oauth?client_id=APP_ID&redirect_uri=CALLBACK_URL
    3. The user will be sent to that URL and then redirected to your CALLBACK_URL with a code in the parameters.
    4. Send a post to the following URL with the code to obtain a new access_token: https://graph.facebook.com/oauth/access_token?client_id=APP_ID&redirect_uri=CALLBACK_URL&client_secret=APP_SECRET&code=CODE&display=popup

Read the post on their dev blog for more information.

Edit (adding example Ruby on Rails code):

Add the following to the top of your ApplicationController:

rescue_from Koala::Facebook::APIError, :with => :handle_fb_exception

Add the following protected method to your ApplicationController:

def handle_fb_exception exception
  if exception.fb_error_type.eql? 'OAuthException'
    logger.debug "[OAuthException] Either the user's access token has expired, they've logged out of Facebook, deauthorized the app, or changed their password"
    oauth = Koala::Facebook::OAuth.new

    # If there is a code in the url, attempt to request a new access token with it
    if params.has_key? 'code'
      code = params['code']
      logger.debug "We have the following code in the url: #{code}"
      logger.debug "Attempting to fetch a new access token..."
      token_hash = oauth.get_access_token_info code
      logger.debug "Obtained the following hash for the new access token:"
      logger.debug token_hash.to_yaml
      redirect_to root_path
    else # Since there is no code in the url, redirect the user to the Facebook auth page for the app
      oauth_url = oauth.url_for_oauth_code :permissions => 'email'
      logger.debug "No code was present; redirecting to the following url to obtain one: #{oauth_url}"
      redirect_to oauth_url
    end
  else
    logger.debug "Since the error type is not an 'OAuthException', this is likely a bug in the Koala gem; reraising the exception..."
    raise exception
  end
end

The Koala calls were all taken from the following 2 tutorials:

• https://github.com/arsduo/koala/wiki/OAuth
• https://github.com/arsduo/koala/wiki/Koala-on-Rails