Deprecated offline_access on facebook with RoR - ruby-on-rails-3

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.
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:
Make a call to the graph with the user's current access_token.
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
The user will be sent to that URL and then redirected to your CALLBACK_URL with a code in the parameters.
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

Answer 2

For those of you who don't have time to make this change, I found that you can disable this migration in Settings -> Advanced. The name of the option is "Remove offline_access permission:"