Doctrine (PHP) - AbsoluteAstronomy.com

Usage demonstration

Doctrine 1.x follows the active record pattern

Active record pattern

In software engineering, the active record pattern is an architectural pattern found in software that stores its data in relational databases. It was named by Martin Fowler in his 2003 book Patterns of Enterprise Application Architecture...

for working with data, where a class

Class (computer science)

In object-oriented programming, a class is a construct that is used as a blueprint to create instances of itself – referred to as class instances, class objects, instance objects or simply objects. A class defines constituent members which enable these class instances to have state and behavior...

corresponds with a database table

Table (database)

In relational databases and flat file databases, a table is a set of data elements that is organized using a model of vertical columns and horizontal rows. A table has a specified number of columns, but can have any number of rows...

. For instance, if a programmer wanted to create a new "User" object in a database, he/she would no longer need to write SQL

SQL

SQL is a programming language designed for managing data in relational database management systems ....

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.

In Doctrine 2.x, the latest release of Doctrine, the entities no longer have to extend a base Active Record class. Instead you just persist them by passing them to the so called Entity Manager:

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

Features

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

XML

Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....

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

Object-oriented programming

Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...

) SQL dialect called DQL (Doctrine Query Language) inspired by Hibernate's

Hibernate (Java)

Hibernate is an object-relational mapping library for the Java language, providing a framework for mapping an object-oriented domain model to a traditional relational database...

HQL. Alternately, the QueryBuilder class (Doctrine_Query in Doctrine 1.x) allows one to construct queries through a fluent interfaceFluent interface In software engineering, a fluent interface is an implementation of an object oriented API that aims to provide for more readable code.... . 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 joinsJoin (SQL) An SQL join clause combines records from two or more tables in a database. It creates a set that can be saved as a table or used as is. A JOIN is a means for combining fields from two tables by using values common to each. ANSI standard SQL specifies four types of JOINs: INNER, OUTER, LEFT, and RIGHT... and fetches related objects automatically. Small projects can be easily constructed without writing queries. Other notable features of Doctrine are: support for hierarchical (tree-structuredTree structure A tree structure is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree, even though the chart is generally upside down compared to an actual tree, with the "root" at the top and the... ) 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 memcachedMemcached In computing, memcached is a general-purpose distributed memory caching system that was originally developed by Danga Interactive for LiveJournal, but is now used by many other sites. It is often used to speed up dynamic database-driven websites by caching data and objects in RAM to reduce the... , SQLiteSQLite SQLite is an ACID-compliant embedded relational database management system contained in a relatively small C programming library. The source code for SQLite is in the public domain and implements most of the SQL standard... or APC; ACIDACID In computer science, ACID is a set of properties that guarantee database transactions are processed reliably. In the context of databases, a single logical operation on the data is called a transaction... 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 CodeGoogle Summer of Code The Google Summer of Code is an annual program, first held from May to August 2005, in which Google awards stipends to hundreds of students who successfully complete a requested free or open-source software coding project during the summer... project. Doctrine 1.0.0 was released on September 1, 2008. The first stable version of Doctrine 2.0 was released on December 22, 2010, after 2.5 years of dedicated development starting in early 2008. Influences Doctrine has been influenced by dozens of projects and many different people. The largest influences have been the JavaJava (programming language) Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities... ORM HibernateHibernate (Java) Hibernate is an object-relational mapping library for the Java language, providing a framework for mapping an object-oriented domain model to a traditional relational database... and ActiveRecord from Ruby on RailsRuby on Rails Ruby on Rails, often shortened to Rails or RoR, is an open source web application framework for the Ruby programming language.-History:... . Both of these ORM solutions have implemented a fully featured solution in the Java and RubyRuby (programming language) Ruby is a dynamic, reflective, general-purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro "Matz" Matsumoto... 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 commonly associate. The channel is on the freenodeFreenode freenode, formerly known as Open Projects Network, is an IRC network used to discuss peer-directed projects. Their servers are all accessible from the domain name [irc://chat.freenode.net chat.freenode.net], which load balances connections by using the actual servers in rotation... 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)Propel (PHP) Propel is a free, open-source object-relational mapping toolkit written in PHP. It is also an integral part of the PHP framework Symfony and was the default ORM up to, and including version 1.2.- History :... List of object-relational mapping software SymfonySymfony Symfony is a web application framework written in PHP which follows the model-view-controller paradigm. Released under the MIT license, Symfony is free software... , a web application frameworkWeb application framework A web application framework is a software framework that is designed to support the development of dynamic websites, web applications and web services. The framework aims to alleviate the overhead associated with common activities performed in Web development... which uses Doctrine by default External links Doctrine homepage Doctrine Documentation Doctrine Trac About Doctrine Download Doctrine Doctrine Community Official Doctrine Blog The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.