Automatic values for updated_at, created_at in Doctrine

This is another option if you would ever want to handle them separately.

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 * @ORM\Table(name="person")
 * @ORM\HasLifecycleCallbacks
 */
class Person
{
    ..........

    /**
     * @var datetime $created
     *
     * @ORM\Column(type="datetime")
     */
    protected $created;

    /**
     * @var datetime $updated
     * 
     * @ORM\Column(type="datetime", nullable = true)
     */
    protected $updated;


    /**
     * Gets triggered only on insert

     * @ORM\PrePersist
     */
    public function onPrePersist()
    {
        $this->created = new \DateTime("now");
    }

    /**
     * Gets triggered every time on update

     * @ORM\PreUpdate
     */
    public function onPreUpdate()
    {
        $this->updated = new \DateTime("now");
    }

    ..........
}

1. You can call $this->setCreatedAt(new \DateTime()) in __construct method.
2. You can use Life Cycle Callbacks

/**
 * @ORM\PrePersist
 * @ORM\PreUpdate
*/
public function updatedTimestamps(): void
{
    $this->setUpdatedAt(new \DateTime('now'));    
    if ($this->getCreatedAt() === null) {
        $this->setCreatedAt(new \DateTime('now'));
    }
}

And don't forget to add into entity class notation: @ORM\HasLifecycleCallbacks

You can implement it as a trait as well - like this:

<?php

namespace App\Entity\Traits;

use DateTime;
use DateTimeInterface;
use Exception;

/**
 * Trait TimeStampableTrait
 * @package App\Entity\Trait
 */
trait TimeStampableTrait
{
    /**
     * @ORM\Column(type="datetime")
     */
    private $createdAt;

    /**
     * @ORM\Column(type="datetime")
     */
    private $updatedAt;

    /**
     * @return DateTimeInterface|null
     * @throws Exception
     */
    public function getCreatedAt(): ?DateTimeInterface
    {
        return $this->createdAt ?? new DateTime();
    }

    /**
     * @param DateTimeInterface $createdAt
     * @return $this
     */
    public function setCreatedAt(DateTimeInterface $createdAt): self
    {
        $this->createdAt = $createdAt;

        return $this;
    }

    /**
     * @return DateTimeInterface|null
     */
    public function getUpdatedAt(): ?DateTimeInterface
    {
        return $this->updatedAt ?? new DateTime();
    }

    /**
     * @param DateTimeInterface $updatedAt
     * @return $this
     */
    public function setUpdatedAt(DateTimeInterface $updatedAt): self
    {
        $this->updatedAt = $updatedAt;

        return $this;
    }

    /**
     * @ORM\PrePersist()
     * @ORM\PreUpdate()
     */
    public function updateTimestamps(): void
    {
        $now = new DateTime();
        $this->setUpdatedAt($now);
        if ($this->getId() === null) {
            $this->setCreatedAt($now);
        }
    }
}

Add this trait to your entity (and don't forget @ORM\HasLifecycleCallbacks() notation):

<?php

namespace App\Entity;

use App\Entity\Traits\TimeStampableTrait;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="App\Repository\MyEntityRepository")
 * @ORM\HasLifecycleCallbacks()
 */
class MyEntity
{
    use TimeStampableTrait;
}

The most convinient solution for me is Timestampable feature of StofDoctrineExtensionsBundle.

Simple configuration and later you are able to make fields createdAt and updatedAt of Entity filled out automatically by adding two simple annotations like:

@Gedmo\Mapping\Annotation\Timestampable(on="create")

and/or

@Gedmo\Mapping\Annotation\Timestampable(on="update")

e.g.

/**
 * @var \DateTime
 * @Gedmo\Mapping\Annotation\Timestampable(on="create")
 * @Doctrine\ORM\Mapping\Column(type="datetime")
 */
protected $createdAt;

/**
 * @var \DateTime
 * @Gedmo\Mapping\Annotation\Timestampable(on="update")
 * @Doctrine\ORM\Mapping\Column(type="datetime")
 */
protected $updatedAt;

Without any redundant code in pure PHP.