Adding a timestampable feature to your entities in Symfony

services.yaml

services:
    App\EventSubscriber\TimestampSubscriber:
        tags:
            - { name: 'doctrine.event_subscriber' }

TimestampableTrait.php

<?php

namespace App\Entity\Traits;

use DateTimeImmutable;
use Doctrine\ORM\Mapping as ORM;

trait TimestampableTrait
{
    /**
     * @ORM\Column(type="datetime_immutable")
     */
    private $createdAt;

    /**
     * @ORM\Column(type="datetime_immutable", nullable=true)
     */
    private $updatedAt;

    public function getCreatedAt(): ?DateTimeImmutable
    {
        return $this->createdAt;
    }

    public function setCreatedAt(?DateTimeImmutable $createdAt): self
    {
        $this->createdAt = $createdAt;

        return $this;
    }

    public function getUpdatedAt(): ?DateTimeImmutable
    {
        return $this->updatedAt;
    }

    public function setUpdatedAt(?DateTimeImmutable $updatedAt): self
    {
        $this->updatedAt = $updatedAt;

        return $this;
    }
}

TimestampSubscriber.php

<?php

namespace App\EventSubscriber;

use App\Entity\Traits\TimestampableTrait;
use DateTime;
use Doctrine\Common\EventSubscriber;
use Doctrine\ORM\Events;
use Doctrine\Persistence\Event\LifecycleEventArgs;

class TimestampSubscriber implements EventSubscriber
{
    /**
     * Ensures that the entity uses the "TimestampableTrait" trait.
     *
     * @param $entity
     */
    private function supports($entity): bool
    {
        return in_array(TimestampableTrait::class, class_uses($entity), true);
    }

    public function prePersist(LifecycleEventArgs $args)
    {
        $entity = $args->getObject();

        if (!$this->supports($entity)) {
            return;
        }

        // sets the createdAt value only if it hasn't been set
        if ($entity->getCreatedAt() === null) {
            $entity->setCreatedAt(new DateTime());
        }
    }

    public function preUpdate(LifecycleEventArgs $args)
    {
        /** @var TimestampableTrait $entity */
        $entity = $args->getObject();

        if (!$this->supports($entity)) {
            return;
        }

        $entity->setUpdatedAt(new DateTime());
    }

    public function getSubscribedEvents(): array
    {
        return [
            Events::prePersist,
            Events::preUpdate,
        ];
    }
}

Usage in an entity

<?php

namespace App\Entity;

use App\Entity\Traits\TimestampableTrait;

/**
 * @ORM\Entity(repositoryClass="App\Repository\UserRepository")
 */
class User
{
    use TimestampableTrait;
}