working with DateTime instances in Doctrine 2

DateTime changes are detected by Reference

When calling EntityManager#flush() Doctrine computes the changesets of all the currently managed entities and saves the differences to the database. In case of object properties (@Column(type=”datetime”) or @Column(type=”object”)) these comparisons are always made BY REFERENCE. That means the following change will NOT be saved into the database:

<?php
/** @Entity */
class Article
{
    /** @Column(type="datetime") */
    private $updated;

    public function setUpdated()
    {
        // will NOT be saved in the database
        $this->updated->modify("now");
    }
}

The way to go would be:

<?php
class Article
{
    public function setUpdated()
    {
        // WILL be saved in the database
        $this->updated = new \DateTime("now");
    }
}​

Refere​nc​e:

http://www.doctrine-project.org/docs/orm/2.0/en/cookbook/working-with-datetime.html