Refresh token using Omniauth-oauth2 in Rails application

I am using omniauth-oauth2 in rails to authenticate to a site which supports oauth2. After doing the oauth dance, the site gives me the following, which I then persist into the database:

1. Access Token
2. Expires_AT (ticks)
3. Refresh token

Is there an omniauth method to refresh the token automatically after it expires or should I write custom code which to do the same?

If custom code is to be written, is a helper the right place to write the logic?

Omniauth doesn't offer this functionality out of the box so i used the previous answer and another SO answer to write the code in my model User.rb

def refresh_token_if_expired
  if token_expired?
    response    = RestClient.post "#{ENV['DOMAIN']}oauth2/token", :grant_type => 'refresh_token', :refresh_token => self.refresh_token, :client_id => ENV['APP_ID'], :client_secret => ENV['APP_SECRET'] 
    refreshhash = JSON.parse(response.body)

    token_will_change!
    expiresat_will_change!

    self.token     = refreshhash['access_token']
    self.expiresat = DateTime.now + refreshhash["expires_in"].to_i.seconds

    self.save
    puts 'Saved'
  end
end

def token_expired?
  expiry = Time.at(self.expiresat) 
  return true if expiry < Time.now # expired token, so we should quickly return
  token_expires_at = expiry
  save if changed?
  false # token not expired. :D
end

And before making the API call using the access token, you can call the method like this where current_user is the signed in user.

current_user.refresh_token_if_expired

Make sure to install the rest-client gem and add the require directive require 'rest-client' in the model file. The ENV['DOMAIN'], ENV['APP_ID'] and ENV['APP_SECRET'] are environment variables that can be set in config/environments/production.rb (or development)