ruby_oauth_callback.rb

class OAuthController < ApplicationController
  def authenticate
  oauth_token = params[:oauth_token]
    oauth_verifier = params[:oauth_verifier]
    
    @user = User.find_by_oauth_token(oauth_token)
    if !@user
      # Do something appropriate, such as a 404
    else
      begin
        oauth_tokens = get_access_token(oauth_token, @user.oauth_token_secret, oauth_verifier)
        # Update @user, save oauth_tokens in the database (in a secure way)
      rescue Exception => e
        # Something went wrong, or user did not give you permissions on Gmail
        # Do something appropriate, potentially try again?
        flash[:error] = "There was an error while authenticating with Gmail. Please try again."
      end     
      redirect_to root_url
    end
  end
end