```ruby
# Somewhere in 2.3 RewindableInput was removed- rack supports it natively
require 'rack/facebook'
require 'rack/facebook_session'

ActionController::Dispatcher.middleware.insert_before( 
  ActionController::ParamsParser,
  Rack::Facebook
)

# ActionController::Dispatcher.middleware.insert_before(
#   ActionController::Base.session_store,
#   Rack::FacebookSession,
#   ActionController::Base.session_options[:key]
# )
```

Add comment to rack setup
user
```ruby
# Somewhere in 2.3 RewindableInput was removed- rack supports it natively
require 'rack/facebook'
require 'rack/facebook_session'

ActionController::Dispatcher.middleware.insert_before( 
  ActionController::ParamsParser,
  Rack::Facebook
)

#use this if you aren't using the cookie store and want to use
# the facebook session key for your session id
# ActionController::Dispatcher.middleware.insert_before(
#   ActionController::Base.session_store,
#   Rack::FacebookSession,
#   ActionController::Base.session_options[:key]
# )
```
assistant