The last chapter was a quick overview of some advanced features of Doctrine: handling Inheritance though Mapped Superclass, Single Table Inheritance, and Class Table Inheritance; the Doctrine event system including lifecycle callbacks, listeners, and subscribers; and finally how to unleash the power of the underlying DBMS for specific use cases with native queries.
Throughout this book, we have learned how to use the Doctrine ORM to create a stable model layer in our PHP applications. We are now familiar with concepts behind Doctrine components and we are able to smartly use its ORM. We also looked at the most powerful (but also complex) features, including entity managers and entity states, mapping information, associations, DQL, hydration, inheritance, events, and native queries. There is still a lot to learn, and many of these topics deserve a dedicated book of their own.
Again, the online documentation of the Doctrine project (available at http://www.doctrine-project.org/) is comprehensive...