xq sale creatAt JMSSerializer¿

<?php

namespace Nvia\CommonBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use JMS\Serializer\Annotation\Exclude;
use JMS\Serializer\Annotation\ExclusionPolicy;
use JMS\Serializer\Annotation\Expose;

/**
 * Country
 *
 * @ORM\Table(name="country")
 * @ORM\Entity(repositoryClass="Nvia\CommonBundle\Entity\Repository\CountryRepository")
 * @ExclusionPolicy("all")
 */
class Country
{
    /**
     * @var string
     *
     * @ORM\Column(name="id", type="string", length=3)
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="NONE")
     * @Expose
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="name", type="string", length=45, nullable=false)
     * @Expose
     */
    private $name;

    /**
     * @var \Nvia\CommonBundle\Entity\Currency
     *
     * @ORM\ManyToOne(targetEntity="Nvia\CommonBundle\Entity\Currency")
     * @ORM\JoinColumn(name="currency_id", referencedColumnName="id", nullable=false)
     */
    private $currency;

    /**
     * @var \Nvia\CommonBundle\Entity\Language
     *
     * @ORM\ManyToOne(targetEntity="Nvia\CommonBundle\Entity\Language")
     * @ORM\JoinColumn(name="language_id", referencedColumnName="id", nullable=false)
     */
    private $language;

    /**
     * @var \DateTime
     *
     * @ORM\Column(name="created_at", type="datetime", nullable=false)
     * @Exclude
     */
    private $createdAt;


    function __construct($id)
    {
        $this->createdAt = new \DateTime('now');
        $this->id = $id;
    }

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

    /**
     * Set name
     *
     * @param string $name
     * @return Country
     */
    public function setName($name)
    {
        $this->name = $name;

        return $this;
    }

    /**
     * Get name
     *
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * Get id
     *
     * @return string
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * Set currency
     *
     * @param \Nvia\CommonBundle\Entity\Currency $currency
     * @return Country
     */
    public function setCurrency(\Nvia\CommonBundle\Entity\Currency $currency = null)
    {
        $this->currency = $currency;

        return $this;
    }

    /**
     * Get currency
     *
     * @return \Nvia\CommonBundle\Entity\Currency
     */
    public function getCurrency()
    {
        return $this->currency;
    }

    /**
     * Set language
     *
     * @param \Nvia\CommonBundle\Entity\Language $language
     * @return Country
     */
    public function setLanguage(\Nvia\CommonBundle\Entity\Language $language = null)
    {
        $this->language = $language;

        return $this;
    }

    /**
     * Get language
     *
     * @return \Nvia\CommonBundle\Entity\Language
     */
    public function getLanguage()
    {
        return $this->language;
    }

    /**
     * Set createdAt
     *
     * @param \DateTime $createdAt
     * @return Country
     */
    private function setCreatedAt($createdAt)
    {
        $this->createdAt = $createdAt;

        return $this;
    }

    /**
     * Get createdAt
     *
     * @return \DateTime
     */
    public function getCreatedAt()
    {
        return $this->createdAt;
    }

    /**
     * Set id
     *
     * @param string $id
     * @return Country
     */
    private function setId($id)
    {
        $this->id = $id;

        return $this;
    }
}