controller.php

<?php
  $event = $this->getDoctrine()
            ->getRepository('WeTimeboxBundle:Event')
            ->findBy(array("edit_id" => $eventId));

Event.php

<?php

namespace PhmLabs\Bundle\WeTimeboxBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 * @ORM\Table(name="events")
 */
class Event {
    /**
     * @ORM\Column(type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\Column(type="string", length=100)
     */
    protected $readonly_id;

    /**
     * @ORM\Column(type="string", length=100)
     */
    protected  $edit_id;

    /**
     * @ORM\Column(type="string", length=255)
     */
    protected $title;

    /**
     * @ORM\Column(type="text")
     */
    protected $description;

    /**
     * @ORM\Column(type="string", length=20)
     */
    protected $start_date;

    /**
     * @ORM\Column(type="string", length=255)
     */
    protected $company_logo;

    /**
     * @ORM\Column(type="boolean")
     */
    protected $public;

    /**
     * @ORM\OneToMany(targetEntity="Item", mappedBy="event_id")
     */
    protected $items;
    
}

item.php

<?php

namespace PhmLabs\Bundle\WeTimeboxBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 * @ORM\Table(name="items")
 */
class Item {
    /**
     * @ORM\Column(type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\Column(type="integer")
     */
    protected $event_id;

    /**
     * @ORM\Column(type="string", length=255)
     */
    protected $title;

    /**
     * @ORM\Column(type="text")
     */
    protected $description;

    /**
     * @ORM\Column(type="string", length=5)
     */
    protected $duration;

    /**
     * @ORM\Column(type="integer", length=3)
     */
    protected $position;
}

/**
 * @ORM\ManyToOne(targetEntity="Event", inversedBy="items")
 */
protected $event_id;

und Items im constructor als Collection initialisieren:

public function __construct()
{
    $this->items = new ArrayCollection();
}

und der schönheit halber noch alles private machen ;)