Symfony2 Datetime TransformationFailed异常

i'm stuck in error when try to generate CRUD in symfony2 I always get the following exception:

"Unable to transform value for property path "xxx": Expected a \DateTime or \DateTimeInterface."

it always happened with the any datetime field here is excerpt of my entity field:

 /**
 * @var \DateTime
 *
 * @ORM\Column(name="date_added", type="datetime", nullable=false)
 */
private $dateAdded = '0000-00-00 00:00:00';


/**
 * Set dateAdded
 *
 * @param \DateTime $dateAdded
 *
 * @return User
 */
public function setDateAdded()
{
    $this->dateAdded = new \DateTime();

    return $this;
}

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

-Also i tried to use easyadmin bundle which generate backend from entities using symfony2 CRUD on the fly but also get the same error so is there something wrong with my entity ?

The $dateAdded field cannot contain a string. It needs to have a DateTime object, because that's whats expected. In other words you need to have a constructor which sets the date:

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

public function __construct() {
    $this->dateAdded = new \DateTime();
}

Also, you need to accept a parameter on your setDate method:

public function setDate($date) {
    $this->dateAdded = $date;
}

As a side note, keep in mind you will need to use a date filter if you'll be displaying the date in a twig template:

{{ entity.dateAdded|date('d.m.Y') }}

Maybe removing the annotation @param \DateTime $dateAdded as your function setDateAdded() has no parameter ?