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)

Getting started with the Doctrine associations


We will specify Doctrine associations, such as other mapping information, using annotations (other methods such as XML and YAML configuration files are also supported. See Chapter 2, Entities and Mapping Information). Doctrine supports the following association types:

  • One-To-One: One entity is linked to one entity

  • Many-To-One: Several entities are linked to one entity (only available for bidirectional associations and always the inverse side of a One-To-Many association)

  • One-To-Many: One entity is linked to several entities

  • Many-To-Many: Several entities are linked to several entities

An association can be unidirectional or bidirectional. Unidirectional associations only have an owning side while bidirectional associations have both an owning side and an inverse side. In other words they can be explained as follows:

  • A unidirectional association can be used in only one way: related entities are retrievable from the main entities. For example, a...