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 Query Builder

QueryBuilder is an object designed to help build the DQL queries through a PHP API with a fluent interface (to find out more about fluent interfaces, see Chapter 2, Entities and Mapping Information). It allows us to retrieve the generated DQL queries through the getDql() method (useful for debugging) or directly use the Query object (provided by Doctrine).


To increase performance, QueryBuilder caches the generated DQL queries and manages an internal state.

The full API and states of the DQL query are documented on the following website:

We will give an in-depth explanation of the findWithComments() method that we created in the PostRepository class.

Firstly, a QueryBuilder instance is created with the createQueryBuilder() method inherited from the base entity repository. The QueryBuilder instance takes a string as a parameter. This string will be used as an alias...