If you missed any of the previous videos you can find them int his playlist: https://www.youtube.com/watch?v=e4-Xgi1vVnU&list=PLqhuffi3fiMN_jVxqlIAILEp4avoBH4wc This video will show you how you can create you can create a custom normalizer in Symfony 4to make changes to your data before serializing it, let me know if you have any question or if you encounter any problems :) Git repository : https://github.com/konshensx16/symfony-todo-backend