/**
 * @ORMOneToMany(targetEntity="Repair", mappedBy="device", cascade={"remove"})
 */
private $repairs;

/**
 * @ORMManyToMany(targetEntity="Color", inversedBy="devices")
 * @ORMJoinTable(name="devices_colors",
 *      joinColumns={@ORMJoinColumn(name="device_id", referencedColumnName="id")},
 *      inverseJoinColumns={@ORMJoinColumn(name="color_id", referencedColumnName="id")}
 *      )
 */
private $colors;

/**
 * @ORMManyToMany(targetEntity="Device", mappedBy="colors")
 */
private $devices;

/**
 * @ORMManyToOne(targetEntity="Device", inversedBy="repairs")
 * @ORMJoinColumn(name="device_id", referencedColumnName="id")
 */
private $device;

/**
 * @ORMManyToMany(targetEntity="Color")
 * @ORMJoinTable(name="repairs_colors",
 *      joinColumns={@ORMJoinColumn(name="repair_id", referencedColumnName="id")},
 *      inverseJoinColumns={@ORMJoinColumn(name="color_id", referencedColumnName="id")}
 *      )
 */
private $colors;

->add('colors', EntityType::class, array(
              'label'=>'Kleuren',
              'class'=>'AppBundle:Color',
              'choice_label'=>'name',
              'choice_value'=>'id',
              'multiple'=>true,
              'expanded'=>true,
              'query_builder'=>function (EntityRepository $er) use ($device) {
                          return $er->createQueryBuilder('c')
                                ->join('AppBundle:Device','d')
                                ->where('d.id = :device')
                                ->setParameter('device', $device);
                    }
              )
        )

SELECT c.name FROM colors c LEFT JOIN devices_colors d ON (d.color_id=c.id) WHERE d.device_id = 1