Using the GoodBarber App API you can get informations about the current user logged into your application. This project shows you how to do it.
This code can be user inside a Custom code section, when the there's a user logged into the app, it displays the ID card of the user. Inside the card a QR Code is displayed generated from the URL of this page.
You just need to upload all the files of this repo in a Custom code section in your GoodBarber backend.