intro.xml

  <chapter id="introduction">
    <title>Introduction</title>
    <sect1 id="about-doctrine">
      <title>About Doctrine</title>
      <para>
        Doctrine is a Object Relational Mapping and database abstraction
        framework for PHP. The DBAL part of Doctrine derives from MDB2. The key
        idea is to provide very intuitive and easy-to-use persistency solution
        (eg. RoR ActiveRecord) with all the advanced features from the more
        heavy-weight solutions (eg. Hibernate).
      </para>
      <para>
        Doctrine Query Language implements EJB 3 OQL specificiation and expands
        it a bit further (it has special LIMIT and OFFSET clauses).
      </para>
      <sect2 id="intro-example">
        <title>Example</title>
        <para>
          You might not understand exactly what's happening at this stage, but
          this example is to give you a general idea of the power of Doctrine.
        </para>

        <programlisting role="php"><![CDATA[
<?php 

    // include the doctrine library
    require_once('lib/Doctrine.php');

    // register the doctrine autoload function
    spl_autoload_register(array('Doctrine', 'autoload'));

    // define the user class
    class User extends Doctrine_Record { 
        public function setTableDefinition() {
            // set 'user' table columns, note that
            // id column is always auto-created
            
            $this->hasColumn('name','string',30);
            $this->hasColumn('username','string',20);
            $this->hasColumn('password','string',16);
            $this->hasColumn('created','integer',11);
        }
    }

    // create a new user
    $user = new User();
    $user->username = "pookey";
    $user->password = "a password!";
    $user->created = time();

    // save the user
    $user->save();

    // lets find the user....
    $query = new Doctrine_Query();
    $query->query('SELECT u.* FROM User u WHERE u.username = ?');
    $users = $query->execute(array('pookey'));
    if (count($users))
    {
      // we found our user!
    }
    else
    {
      // we didn't find our user, oh no!
    }
?>]]></programlisting>
      </sect2>
    </sect1>

    <sect1 id="features">
      <title>Features</title>
      <sect3 id="features-general">
        <title>
          General Features
        </title>
        <itemizedlist>
          <listitem>Fully object-oriented following best practices and design patterns</listitem>
          <listitem>Multiple databases</listitem>
          <listitem>Database connection pooling with connection-record -registry</listitem>
          <listitem>Runtime configuration (no XML needed!)</listitem>
          <listitem>Very modular structure (only uses the needed features)</listitem>
          <listitem>The runtime components can be compiled into a single fileM</listitem>
          <listitem>Leveled configuration (attributes can be set at global, connection and table levels)</listitem>
        </itemizedlist>
      </sect3>
      <sect3 id="features-abstraction">
        <title>
          Database Abstraction
        </title>
        <itemizedlist>
          <listitem>A DSN (data source name) or array format for specifying database servers</listitem>
          <listitem>Datatype abstraction and on demand datatype conversion</listitem>
          <listitem>supports PDO</listitem>
          <listitem>Database query profiling</listitem>
          <listitem>Query caching</listitem>
          <listitem>Sequence / autoincrement emulation</listitem>
          <listitem>Replace emulation</listitem>
          <listitem>RDBMS management methods (creating, dropping, altering)</listitem>
          <listitem>SQL function call abstraction</listitem>
          <listitem>SQL expression abstraction</listitem>
          <listitem>Pattern matching abstraction</listitem>
          <listitem>Portable error codes</listitem>
          <listitem>Nested transactions</listitem>
          <listitem>Transaction isolation abstraction</listitem>
          <listitem>Transaction savepoint abstraction</listitem>
          <listitem>Index/Unique Key/Primary Key support</listitem>
          <listitem>Ability to read the information schema</listitem>
          <listitem>Reverse engineering schemas from an existing database</listitem>
          <listitem>LIMIT / OFFSET emulation </listitem>
        </itemizedlist>
      </sect3>
      <sect3 id="features-orm">
        <title>
        Object Relational Mapping
        </title>
        <sect4 id="features-orm-general">
          <title>
            General Features
          </title>
          <itemizedlist>
            <listitem>Validators</listitem>
            <listitem>Transactional errorStack for easy retrieval of all errors</listitem>
            <listitem>EventListeners</listitem>
            <listitem>UnitOfWork pattern (easy saving of all pending objects)</listitem>
            <listitem>Uses ActiveRecord pattern</listitem>
            <listitem>State-wise records and transactions</listitem>
            <listitem>Importing existing database schemas to Doctrine ActiveRecord objects</listitem>
            <listitem>Exporting Doctrine ActiveRecords to database (= automatic table creation)</listitem>
          </itemizedlist>
        </sect4>
        <sect4 id="features-orm-mapping">
          <title>
            Mapping
          </title>
          <itemizedlist>
            <listitem>Composite, Natural, Autoincremented and Sequential identifiers</listitem>
            <listitem>PHP Array / Object data types for columns (automatic serialization/unserialization)</listitem>
            <listitem>Gzip datatype for all databases</listitem>
            <listitem>Emulated enum datatype for all databases</listitem>
            <listitem>Datatype abstraction</listitem>
            <listitem>Column aggregation inheritance</listitem>
            <listitem>One-class-one-table inheritance as well as One-table</listitem>
            <listitem>One-to-many, many-to-one, one-to-one and many-to-many relations</listitem>
            <listitem>Self-referencing relations even for association table relations</listitem>
            <listitem>Relation aliases</listitem>
          </itemizedlist>
        </sect4>

        <sect4 id="features-orm-population">
          <title>
            Object population
          </title>
          <itemizedlist>
            <listitem>DQL (Doctrine Query Language), an EJB 3 spec compliant OQL</listitem>
            <listitem>The limit-subquery-algorithm</listitem>
            <listitem>OO-style query API for both DQL and raw SQL</listitem>
            <listitem>Object population from database views</listitem>
            <listitem>Object population through raw SQL</listitem>
          </itemizedlist>
        </sect4>

        <sect4 id="features-orm-locking">
          <title>
            Transactions and locking
          </title>
          <itemizedlist>
            <listitem>Pessimistic offline locking</listitem>
            <listitem>Savepoints, transaction isolation levels and nested transactions</listitem>
            <listitem>Transactional query optimization (gathering of DELETE statements) </listitem>
          </itemizedlist>
        </sect4>
      </sect3>
    </sect1>

    <sect1 id="requirements">
      <title>Requirements</title>
      <para>
        Doctrine requires PHP >= 5.1, and it doesn't require any external libraries.
        It runs on both windows and *nix based platforms.
      </para>
      <para>
        For database abstraction Doctrine uses PDO which is bundled with php by
        default.  You will need PDO support for whatever database you intend to
        use, and if you want to be able to run the included unit tests, you
        will need SQLite support.
      </para>
      <para>
        Doctrine also requires a little adodb-hack for table creation,
        which comes with doctrine.
      </para>
    </sect1>

    <sect1 id="community">
      <title>Community</title>
      <para>
        Doctrine has 3 mailing lists, an IRC channel, a forum, and a wiki/trac.
      </para>
      <sect2 id="community-mailinglist">
        <title>Mailing Lists</title>
        <para>
          The 'user' mailing list is for discussing the usage of doctrine.
          To subscribe to this list, send a blank email to
          <email>doctrine-user+subscribe@lists.pengus.net</email>
        </para>
        <para>
          The 'dev' mailing list is used for discussion of the development
          of doctrine.  To subscribe to this list, send a blank email to
          <email>doctrine-dev+subscribe@lists.pengus.net</email>
        </para>
        <para>
          The 'svn' mailing list is a read-only list, which users and developers
          can subscribe to to receive commit logs to the SVN repository.  This
          list is quite high traffic, as every commit to the repository results
          in an email containing the changelog entry and diffs of the changed
          files.
          To subscribe to this list, send a blank email to
          <email>doctrine-svn+subscribe@lists.pengus.net</email>
        </para>
      </sect2>
      <sect2 id="community-irc">
        <title>IRC</title>
        <para>
          The #doctrine IRC channel can be found on the freenode network. The fastest way of getting bugs fixed and features being implemented is joining our irc channel and pointing out the issue to one of the developers.
        </para>
      </sect2>
      <sect2 id="community-wiki">
        <title>Wiki and Trac</title>
        <para>
          A wiki/trac install can be found at <ulink
          url="http://doctrine.pengus.net/trac">http://doctrine.pengus.net/trac</ulink>
        </para>
      </sect2>
      <sect2 id="community-forum">
        <title>Forum</title>
        <para>
          The Doctrine forum can be found here:
          <ulink url="http://www.phpbbserver.com/phpdoctrine/">http://www.phpbbserver.com/phpdoctrine/</ulink>
        </para>
      </sect2>
    </sect1>

    <sect1 id="contributing">
      <title>Contributing/Reporting Bugs</title>
      <para>
        Doctrine is constantly under development, and is always happy for new
        developers to contribute to the project.
      </para>
      <para>
        To get an account on trac to submit bugs and make suggestions, or to get
        access to commit to the SVN repository, please visit the IRC channel, or
        email the users mailing list.
      </para>
      <para>
        If you are unsure as to wether you have found a bug or not, please
        consider joining us on IRC, or maining the user mailing list to confirm
        your problem.
      </para>
    </sect1>

    <sect1 id="installation">
      <title>Installation</title>
      <para>
        As of the time of writing, there is no stable release of doctrine.  That is not to say
        that it's unstable, but simply that the best way to install it is to aquire it from
        SVN.
      </para>
      <para>
        To get the latest copy, simple check out 'trunk' from SVN.  You will
        need <ulink url="http://subversion.tigris.org/">subversion</ulink>
        install to check out doctrine.  If you are unable to install subversion
        for whatever reason, see below for details on downloading a snapshot.
      </para>
      <screen>
        <prompt>bash $ </prompt><command>mkdir <replaceable>doctrine</replaceable></command>
        <prompt>bash $ </prompt><command>cd <replaceable>doctrine</replaceable></command>
        <prompt>bash $ </prompt><command>svn checkout http://doctrine.pengus.net/svn/trunk .</command>
      </screen>
      <para>
        Daily snapshots can be found at 
        <ulink url="http://doctrine.pengus.net/downloads/">http://doctrine.pengus.net/downloads/</ulink>
        and the latest daily snapshot can always be found at
        <ulink url="http://doctrine.pengus.net/downloads/latest-snapshot.tar.gz">http://doctrine.pengus.net/downloads/latest-snapshot.tar.gz</ulink>
      </para>
    </sect1>

    <sect1 id="include-and-autoload">
      <title>Include and autoload</title>
      <para>
        In order to use Doctrine in your project, you must first include the main
        library file called 'Doctrine.php'.
      </para>
      <programlisting role="php"><![CDATA[
<?php
  require_once('path-to-doctrine/lib/Doctrine.php');
?>]]></programlisting>
      <para>
        Doctrine supports <ulink
        url="http://www.php.net/autoload">Autoloading</ulink> for including
        files so that you don't have to include anything more then the base
        file. There are two different strategies that can be used to do this,
        as shown below.
      </para>

      <para>
        You can use the <emphasis>__autoload</emphasis> function to call the
        'Doctrine::autoload($class)' method, for example:
      </para>
      <programlisting role="php"><![CDATA[
<?php
  function __autoload($class) {
    Doctrine::autoload($class);
  }
?>]]></programlisting>
    
      <para>
        If your project already uses autoload or you have other libraries
        that use it, you can use <ulink
        url="http://www.php.net/manual/en/function.spl-autoload-register.php">spl_autoload_register</ulink>
        to register multiple autoloading functions.
      </para>

      <programlisting role="php"><![CDATA[
<?php
  spl_autoload_register(array('Doctrine', 'autoload'));
?>]]></programlisting>
    </sect1>

    <sect1 id="compiling">
      <title>Compiling</title>
      <para>
        Compiling is a method for making a single file of the most used doctrine
        runtime components.  Including this compiled file instead of multiple files
        (in worst cases dozens of files) can improve performance by an order of
        magnitude.
      </para>
      <para>
        In cases where this might fail, a Doctrine_Exception is thrown detailing
        the error.
      </para>
      <programlisting role="php"><![CDATA[
<?php
  Doctrine::compile();

  // on some other script:
  require_once('path_to_doctrine/Doctrine.compiled.php');
?>]]></programlisting>
    </sect1>

    <sect1 id="new-project">
      <title>Starting a new project</title>
      <para>
        Doctrine_Record is the basic component of every doctrine-based project.
        There should be atleast one Doctrine_Record for each of your database
        tables.  Doctrine_Record follows the <ulink
        url="http://www.martinfowler.com/eaaCatalog/activeRecord.html">Active
        Record pattern</ulink>
      </para>
      <para>
        Doctrine auto-creates database tables and always adds a primary key
        column named 'id' to tables that don't have any primary keys
        specified. The only thing you need to do to create database tables is
        defining a class which extends Doctrine_Record and setting a
        setTableDefinition method with hasColumn() method calls.
      </para>
      <para>
        Below is a short example:
      </para>
      <para>
        We want to create a database table called 'user' with columns
        id(primary key), name, username, password and created. Provided that
        you have already installed Doctrine these few lines of code are all you
        need:
      </para>
      <programlisting role="php"><![CDATA[
<?php 

    require_once('lib/Doctrine.php');

    spl_autoload_register(array('Doctrine', 'autoload'));

    class User extends Doctrine_Record { 
        public function setTableDefinition() {
            // set 'user' table columns, note that
            // id column is always auto-created
            
            $this->hasColumn('name','string',30);
            $this->hasColumn('username','string',20);
            $this->hasColumn('password','string',16);
            $this->hasColumn('created','integer',11);
        }
    }
?>]]></programlisting>
      <para>
        We now have a user model that supports basic CRUD opperations!
      </para>
    </sect1>
  </chapter>