Book Image

Persistence in PHP with Doctrine ORM

By : Kevin Dunglas
Book Image

Persistence in PHP with Doctrine ORM

By: Kevin Dunglas

Overview of this book

Doctrine 2 has become the most popular modern persistence system for PHP. It can either be used as a standalone system or can be distributed with Symfony 2, and it also integrates very well with popular frameworks. It allows you to easily retrieve PHP object graphs, provides a powerful object-oriented query language called DQL, a database schema generator tool, and supports database migration. It is efficient, abstracts popular DBMS, and supports PHP 5.3 features. Doctrine is a must-have for modern PHP applications. Persistence in PHP with Doctrine ORM is a practical, hands-on guide that describes the full creation process of a web application powered by Doctrine. Core features of the ORM are explained in depth and illustrated by useful, explicit, and reusable code samples. Persistence in PHP with Doctrine ORM explains everything you need to know to get started with Doctrine in a clear and detailed manner. From installing the ORM through Composer to mastering advanced features such as native queries, this book is a full overview of the power of Doctrine. You will also learn a bunch of mapping annotations, create associations, and generate database schemas from PHP classes. You will also see how to write data fixtures, create custom entity repositories, and issue advanced DQL queries. Finally it will teach you to play with inheritance, write native queries, and use built-in lifecycle events. If you want to use a powerful persistence system for your PHP application, Persistence in PHP with Doctrine ORM is the book you.
Table of Contents (12 chapters)

Using the entity repositories


Entity repositories are classes responsible for accessing and managing entities. Just like entities are related to the database rows, entity repositories are related to the database tables.

We have already used default entity repositories provided by Doctrine to retrieve the entities in the previous chapters. All the DQL queries should be written in the entity repository related to the entity type they retrieve. It hides the ORM from other components of the application and makes it easier to re-use, refactor, and optimize the queries.

Note

Doctrine entity repositories are an implementation of the Table Data Gateway design pattern. For more details, visit the following website:

http://martinfowler.com/eaaCatalog/tableDataGateway.html

A base repository, available for every entity, provides useful methods for managing the entities in the following manner:

  • find($id): It returns the entity with $id as an identifier or null

    Note

    It is used internally by the find() method...