Preface

Doctrine 2 has become the most popular modern persistence system for PHP. It is distributed with the standard edition of the Symfony2 framework, can be used standalone in any PHP project and integrates very well with Zend Framework 2, CodeIgniter, or Laravel. It is efficient, automatically abstracts popular database managing systems, supports PHP 5.3 features (including namespaces), is installable through Composer, and has an extensively tested quality code base.

Doctrine's ORM library allows easy persisting and retrieving of PHP object graph, without writing any SQL query by hand. It also provides a powerful object-oriented SQL-like query language called DQL, a database schema generator tool, an event system, and much more.

To discover this must-have library, we will together build a typical small, blog engine.

What this book covers

Chapter 1, Getting Started with Doctrine 2, explains how to install Common, DBAL, and ORM libraries through Composer, get our first entity manager, and configure command-line tools after presenting the project we built throughout the book (the architecture of Doctrine and the configuration of the development environment).

Chapter 2, Entities and Mapping Information, introduces the concept of Doctrine entities. We will create a first entity, map it to the database with annotations, generate the database schema, create data fixtures, and, finally, lay the foundation of the user interface of the blog.

Chapter 3, Associations, explains how to handle associations between the PHP objects and the ORM. We will create new entities, detail one-to-one, one-to-many, and many-to-many associations, generate the underlying database schema, create data fixtures and use associations in the user interface.

Chapter 4, Building Queries, creates entity repositories and helps understand how to use the query builder for generating DQL queries and retrieving entities. We will also take a look at aggregate functions.

Chapter 5, Going Further, will take a look at the advanced features of Doctrine. We will see different ways in which Doctrine can manage object inheritance, play with entity lifecycle events, and create native SQL queries.

What you need for this book

To execute examples of this book, you just need PHP 5.4+ a text editor, or a PHP IDE, and your favorite browser.

Who this book is for

Readers should have a good knowledge of object-oriented programming, PHP (including features introduced in PHP 5.3 and 5.4), and general database concepts.

Conventions

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, and user input are shown as follows: "The NativeQuery class allows you to execute native SQL queries and to get their results as Doctrine entities."

A block of code is set as follows:

    /**
     * Adds comment
     *
     * @param  Comment $comment
     * @return Post
     */
    public function addComment(Comment $comment)
    {
        $this->comments[] = $comment;
        $comment->setPost($this);

        return $this;
    }

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

    /**
     * Adds comment
     *
     * @param  Comment $comment
     * @return Post
     */
    public function addComment(Comment $comment)
    {
        $this->comments[] = $comment;
        $comment->setPost($this);

        return $this;
    }

Any command-line input or output is written as follows:

# php bin/load-fixtures.php

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "The following text must be printed in the terminal: ATTENTION: This operation should not be executed in a production environment."

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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