For this chapter, you will need an Odoo server that you can command from a terminal session.
The code in this chapter depends on the code that we created in Chapter 3, Your First Odoo Application. You should have your add-ons path and should install the library_app module. You can find the code in the ch04 directory of the GitHub repository at https://github.com/PacktPublishing/Odoo-12-Development-Essentials-Fourth-Edition.