Book Image

Domain-Driven Design in PHP

By : Keyvan Akbary, Carlos Buenosvinos, Christian Soronellas
Book Image

Domain-Driven Design in PHP

By: Keyvan Akbary, Carlos Buenosvinos, Christian Soronellas

Overview of this book

Domain-Driven Design (DDD) has arrived in the PHP community, but for all the talk, there is very little real code. Without being in a training session and with no PHP real examples, learning DDD can be challenging. This book changes all that. It details how to implement tactical DDD patterns and gives full examples of topics such as integrating Bounded Contexts with REST, and DDD messaging strategies. In this book, the authors show you, with tons of details and examples, how to properly design Entities, Value Objects, Services, Domain Events, Aggregates, Factories, Repositories, Services, and Application Services with PHP. They show how to apply Hexagonal Architecture within your application whether you use an open source framework or your own.
Table of Contents (24 chapters)
Title Page
Credits
Foreword
About the Authors
Acknowledgments
www.PacktPub.com
Customer Feedback
Dedication
Preface
14
Bibliography
15
The End

Identity Operation


As stated before, the Identity of an Entity is what defines it. So then, handling it is an important aspect of the Entity. There are usually four ways to define the Identity of an Entity: the persistence mechanism provides the Identity, a client provides the Identity, the application itself provides the Identity, or another Bounded Context provides the Identity.

Persistence Mechanism Generates Identity

Usually, the simplest way of generating the Identity is to delegate it to the persistence mechanism, because the vast majority of persistence mechanisms support some kind of Identity generation — like MySQL's AUTO_INCREMENT attribute or Postgres and Oracle sequences. This, although simple, has a major drawback: we won't have the Identity of the Entity until we persist it. So to some degree, if we're going with persistence mechanism-generated Identities, we'll couple the Identity operation with the underlying persistence store:

CREATE TABLE `orders` (
    `id` int(11) NOT NULL...