Doctrine2 not update DateTime [duplicate] - symfony

Question

This question already has answers here:
Doctrine2 ORM does not save changes to a DateTime field
(3 answers)
Closed 8 years ago.
I think I have found a bug which I can not find solution ..
I try to update the datetime field, but do not update it, don't gives me an error.
Move all other fields modifies them correctly, but the datetime field no.
$em = $this->getDoctrine()->getManager();
$entity = $em->getRepository('MyOwnBundle:Events')->find($id);
$In = $entity->getDateIn();
$In->modify('+1 day');
$entity->setDateIn($In);
$em->flush();
I also tried to insert a DateTime() object directly but does not update at all!
$entity->setDateIn(new \DateTime());
Is there a solution to this problem?
I installed symfony 2.1 and doctrine 2.3.3
EDIT
Event entity:
/**
* Events
*
* #ORM\Table()
* #ORM\Entity(repositoryClass="My\OwnBundle\Entity\EventsRepository")
*/
class Events
{
/**
* #var integer
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #var string
*
* #ORM\Column(name="name", type="string", length=100)
*/
private $name;
/**
* #var string
*
* #ORM\Column(name="description", type="text")
*/
private $description;
/**
* #var \DateTime
*
* #ORM\Column(name="dateIn", type="datetime")
*/
private $dateIn;
/**
* #var \DateTime
*
* #ORM\Column(name="dateOut", type="datetime")
*/
private $dateOut;
....
/**
* Set dateIn
*
* #param \DateTime $dateIn
* #return Events
*/
public function setDateIn($dateIn)
{
$this->dateIn = $dateIn;
return $this;
}
/**
* Get dateIn
*
* #return \DateTime
*/
public function getDateIn()
{
return $this->dateIn;
}
/**
* Set dateOut
*
* #param \DateTime $dateOut
* #return Events
*/
public function setDateOut($dateOut)
{
$this->dateOut = $dateOut;
return $this;
}
/**
* Get dateOut
*
* #return \DateTime
*/
public function getDateOut()
{
return $this->dateOut;
}
....

Answer 1

The modify() method will not update the entity since Doctrine tracks DateTime objects by reference. You need to clone your existing DateTime object, giving it a new reference. Modify the new one and then set is as a new timestamp.
For more information, see the article in the Doctrine Documentation.

Answer 2

the entity is right, but you need to persist your entity with $em->persist($entity) and you don't need to set again the date because the datetime is passed by reference
$em = $this->getDoctrine()->getManager();
$entity = $em->getRepository('MyOwnBundle:Events')->find($id);
$entity->getDateIn()->modify('+1 day');
$em->persist($entity);
$em->flush();