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)

Understanding the @ManyToOne and @OneToMany annotations with the comment system

Let's start with the comments. Visitors to our blog should be able to react to our posts. We have to create a new Comment Doctrine entity type storing the reader's comments. Comment entities will be linked to one Post entity. One post can have many comments, and one comment is associated with a sole post.

The following E-R diagram represents the MySQL schema that will be generated using mapping information:

Creating the Comment entity class (owning side)

The Comment entity has the following four properties:

  • id: This is a unique identifier of the comment

  • body: This represents the comment's text

  • publicationDate: This is the date of publication of the comment

  • post_id: This represents the post related to the comment

Here is the first code snippet of the Comment entity, containing annotated properties. It must be placed in the Comment.php file at the src/Blog/Entity/ location.


namespace Blog\Entity;

use Doctrine...