Алексей Павлов

$entityA1 = $entity_manager->getRepository(...)->find(1);
$entityA1->addEntitiesB(new EntityB());

$entityA2 = $entity_manager->getRepository(...)->find(1); // получаем новый объект (из базы)
$entitiesB = $entityA2->getEntitiesB(); // пусто
$entitiesB = $entityA1->getEntitiesB(); // а тут будет сохранённый объект

class DefaultController extends Controller {
    public function showAction($login)
    {
        $human = $this->get("PeopleService")->getByLogin($login);
    }
}

<?php

namespace AppBundle\DBAL;

use Doctrine\DBAL\Types\Type;
use Doctrine\DBAL\Platforms\AbstractPlatform;

abstract class EnumType extends Type
{
    protected $name;

    public static $VALUES = array();

    public static function getValues()
    {
        return array_combine(static::$VALUES, static::$VALUES);
    }

    public function getSqlDeclaration(array $fieldDeclaration, AbstractPlatform $platform)
    {
        $values = array_map(function($val) { return "'".$val."'"; }, static::$VALUES);

        return "ENUM(".implode(", ", $values).") COMMENT '(DC2Type:".$this->name.")'";
    }

    public function convertToPHPValue($value, AbstractPlatform $platform)
    {
        return $value;
    }

    public function convertToDatabaseValue($value, AbstractPlatform $platform)
    {
        if (!in_array($value, static::$VALUES)) {
            throw new \InvalidArgumentException("Invalid value '$value' for enum '$this->name'.");
        }
        return $value;
    }

    public function getName()
    {
        return $this->name;
    }
}

<?php

namespace AppBundle\DBAL;

class GenderType extends EnumType
{
    protected $name = 'gender';
    public static $VALUES = array('male', 'female');
}

doctrine:
    dbal:
        # ...
        types:
            gender: AppBundle\DBAL\GenderType
        mapping_types:
            enum: string
            gender: gender

<?php

namespace AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Gedmo\Mapping\Annotation as Gedmo;

/**
 * @ORM\Entity
 */
class Person
{
    // other fields

    /**
     * @var string
     *
     * @ORM\Column(type="gender")
     */
    protected $gender;

    // setters & getters
}

foreach (GenderType::$VALUES as $gender) {
    echo $gender;
}

namespace YourBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 */
class User
{
    /**
     * @ORM\Column(type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=100, nullable=true)
     */
    private $firstName;

    /**
     * @ORM\Column(type="string", length=100, nullable=true)
     */
    private $lastName;

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

    /**
     * @ORM\Column(type="string", length=100, unique=true)
     */
    private $email;

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

    // getters & setters
}