Attachments to Doctrine Jira Issue DDC-251 - https://github.com/doctrine/doctrine2/issues/3232

10280_Collection.php

<?php
namespace Entities {
/**
 * @Entity
 * @InheritanceType("SINGLE_TABLE")
 * @DiscriminatorColumn(name="foobar", type="integer")
 * @DiscriminatorMap({"0" = "Entities\Foo\Collection", "1" = "Collection"})
 */
class Collection
{
  /**
   * @Id
   * @GeneratedValue(strategy="AUTO")
   * @Column(type="integer")
   */
  protected $id;

  /**
   * @OneToMany(targetEntity="Collection", mappedBy="parent")
   */
  protected $children;

  /**
   * @ManyToOne(targetEntity="Collection")
   * @JoinColumn(name="parent_id", referencedColumnName="id")
   */
  protected $parent;

  /**
   * @Column(type="string", nullable=true)
   */
  protected $name;


  public function getId()
  {
    return $this->id;
  }

  public function setParent(Collection $parent)
  {
    $this->parent = $parent;
  }

  public function setName($value)
  {
    $this->name = $value;
  }
}

}

namespace Entities\Foo {
/** @Entity */
class Collection extends \Entities\Collection
{
}

}

10281_index.php

<?php
/**
 * Welcome to Doctrine 2.
 * 
 * This is the index file of the sandbox. The first section of this file
 * demonstrates the bootstrapping and configuration procedure of Doctrine 2.
 * Below that section you can place your test code and experiment.
 */

use Doctrine\Common\ClassLoader,
    Doctrine\ORM\Configuration,
    Doctrine\ORM\EntityManager,
    Doctrine\Common\Cache\ApcCache,
    Entities\Collection;

require '../../lib/Doctrine/Common/ClassLoader.php';

// Set up class loading. You could use different autoloaders, provided by your favorite framework,
// if you want to.
$doctrineClassLoader = new ClassLoader('Doctrine', realpath(__DIR__ . '/../../lib'));
$doctrineClassLoader->register();
$entitiesClassLoader = new ClassLoader('Entities', __DIR__);
$entitiesClassLoader->register();
$proxiesClassLoader = new ClassLoader('Proxies', __DIR__);
$proxiesClassLoader->register();

// Set up caches
$config = new Configuration;
$cache = new ApcCache;
$config->setMetadataCacheImpl($cache);
$config->setQueryCacheImpl($cache);

// Proxy configuration
$config->setProxyDir(__DIR__ . '/Proxies');
$config->setProxyNamespace('Proxies');

// Database connection information
$connectionOptions = array(
    'driver' => 'pdo_sqlite',
    'path' => 'database.sqlite'
);

// Create EntityManager
$em = EntityManager::create($connectionOptions, $config);

## PUT YOUR TEST CODE BELOW

$collection1 = new Collection;
$collection1->setName("Collection number one");
$em->persist($collection1);

$collection2 = new Collection;
$collection2->setName("Collection number one");
$collection2->setParent($collection1);
$em->persist($collection2);

$em->flush();

$em->clear();

$dql = "SELECT c FROM Entities\Collection c WHERE c.id = :id";
$q = $em->createQuery($dql);
$q->setParameter("id", 2);

$collection1 = $q->getSingleResult(\Doctrine\ORM\Query::HYDRATE_OBJECT);

$em->flush();