Doctrine (PHP)

Doctrine

File:Doctrine logo white.png
Stable release	1.2.1 / December 7, 2009
Written in	PHP
Operating system	Cross-platform
Type	Object-relational mapping framework
License	GNU Lesser General Public License
Website	http://www.doctrine-project.org

Doctrine is an object-relational mapper (ORM) for PHP 5.2.3+ that sits on top of a database abstraction layer. It allows easy access to all types of databases, such as MySQL, through the use of PHP objects.

Usage demonstration

Doctrine follows the active record pattern for working with data, where a class corresponds with a database table. For instance, if a programmer wanted to create a new "User" object in a database, he/she would no longer need to write SQL queries, but instead could use the following PHP code:

 $user = new User();
 $user->name = "john";
 $user->password = "doe";
 $user->save();
 echo "The user with id $user->id has been saved.";

Object-related functionality can be added to the objects themselves, instead of being spread around the application. This can improve the ease of maintenance of the software project.

Features

File:Doctrine-layers.jpg

Overview of Doctrine

One feature of Doctrine is the low level of configuration that is needed to start a project. Doctrine can generate object classes from an existing database, and the programmer can then specify relations and add custom functionality to the generated classes. There is no need to generate or maintain complex XML database schemas, as seen in many other frameworks.

Another key feature of Doctrine is the ability to optionally write database queries in an OO (object oriented) SQL dialect called DQL (Doctrine Query Language) inspired by Hibernate's HQL. Alternately, the Doctrine_Query class allows one to construct queries through a fluent interface. These interfaces provide developers with powerful alternatives to SQL which maintain flexibility and still allow for switching of database back-ends, without requiring any code duplication.

Writing queries explicitly however is not always necessary, as Doctrine performs joins and fetches related objects automatically. Small projects can be easily constructed without writing queries.

Other notable features of Doctrine are:

• support for hierarchical (tree-structured) data;
• support for hooks (methods which can validate or modify database input and output) and event listeners to structure business-related logic;
• column aggregation inheritance (similar objects can be stored in one database table, with one type-column specifying the subtype of the particular object - the correct subclass is always returned when a query is done);
• a caching framework, making use of several backends such as memcached, SQLite or APC;
• ACID transactions;
• model behaviors (sluggable, timestampable, nested set, internationalization, audit log, search index);
• database migrations;
• a "compile" function to combine many PHP files of the framework into one, to avoid the performance hit usually incurred by including the many PHP files of a framework.

History

Doctrine was started by Konsta Vesterinen, also known as zYne-. The project's initial commit was made on April 13, 2006 to the svn repository. As the project became more mature, the adoption began to pick up. Before long, the community was active and development was receiving regular contributions, among others from the Google Summer of Code project.

Doctrine 1.0.0 was released on September 1, 2008.

Influences

Doctrine has been influenced by dozens of projects and many different people. The largest influences have been the Java ORM Hibernate and ActiveRecord from Ruby on Rails. Both of these ORM solutions have implemented a fully featured solution in the Java and Ruby languages. The purpose of the Doctrine project is to build an equally powerful solution for the PHP language.

Community

• There is an active IRC channel where users and developers of Doctrine hang out. The channel is on the freenode network (irc.freenode.net); the channel name is #doctrine. irc://irc.freenode.net/#doctrine
• User mailing list: http://groups.google.com/group/doctrine-user
• Development mailing list: http://groups.google.com/group/doctrine-dev
• Commit log mailing list: http://groups.google.com/group/doctrine-svn

See also

• Propel (PHP)
• List of object-relational mapping software
• Symfony, a web application framework which optionally uses Doctrine

External links

• Doctrine homepage
• Doctrine Documentation
• "My First Project" tutorial
• Doctrine Trac
• About Doctrine
• Download Doctrine
• Doctrine Community
• Official Doctrine Blog