Using the CQRS design pattern

In the Legacy core, all the controllers use the ObjectModel child classes to manage the interactions with the database for reading and writing. Whereas in the Symfony modern controller, the core uses the CQRS design pattern with the Command and Query objects.

Using a Command object and its CommandHandler class in the CommandBus

If you have to do an UPDATE, DELETE, or INSERT action in the database, you mustn’t directly call Doctrine and handle it directly inside the controller. Instead, you should use a Command object that contains the necessary data for your action to be done. Every type of Command object has a linked CommandHandler class containing a handle() method responsible for executing the desired action.

Prestashop uses a CommandBus, managed by a library called Tactician, which is like a big pipe in which you can put your Commands, and it processes them one by one, matching each Command object with its CommandHandler and executing...