Using Api Platform, automatically assign user to Object (OneToMany)

This should be possible using an EventListener: https://api-platform.com/docs/core/events

With these you can hook into the internal process of ApiPlatform process without a new controller. Perfect fit for your usecase.

An implementation could look like this:

<?php
// api/src/EventSubscriber/AddOwnerToArticleSubscriber.php

namespace App\EventSubscriber;

use ApiPlatform\Core\EventListener\EventPriorities;
use App\Entity\Article;
use App\Entity\User;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent;
use Symfony\Component\HttpKernel\KernelEvents;
use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;

final class AddOwnerToArticleSubscriber implements EventSubscriberInterface
{

    /**
     * @var TokenStorageInterface
     */
    private $tokenStorage;

    public function __construct(TokenStorageInterface $tokenStorage)
    {

        $this->tokenStorage = $tokenStorage;
    }

    public static function getSubscribedEvents()
    {
        return [
            KernelEvents::VIEW => ['attachOwner', EventPriorities::PRE_WRITE],
        ];
    }

    public function attachOwner(GetResponseForControllerResultEvent $event)
    {
        $article = $event->getControllerResult();
        $method = $event->getRequest()->getMethod();

        if (!$article instanceof Article || Request::METHOD_POST !== $method) {

            // Only handle Article entities (Event is called on any Api entity)
            return;
        }

        // maybe these extra null checks are not even needed
        $token = $this->tokenStorage->getToken();
        if (!$token) {
            return;
        }

        $owner = $token->getUser();
        if (!$owner instanceof User) {
            return;
        }


        // Attach the user to the not yet persisted Article
        $article->setUser($owner);

    }
}

You can create an entity named Base and, you can have some property like "createdBy", "modifiedBy", "createdAt", "modifiedAt", "status" in this class.

<?php
   
namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Serializer\Annotation\Groups;

/**
 * @ORM\MappedSuperclass()
 */
class Base implements PublishedInfoEntityInterface
{

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

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

    /**
     * @ORM\ManyToOne(targetEntity="User")
     * @ORM\JoinColumn(nullable=true)
     */
    private $createdBy;

    /**
     * @ORM\ManyToOne(targetEntity="User")
     * @ORM\JoinColumn(nullable=true)
     */
    private $modifiedBy;

    /**
     * @ORM\Column(type="integer", nullable=true, length=2)
     */
    private $status;

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

    public function setCreatedAt(\DateTimeInterface $createdAt): PublishedInfoEntityInterface
    {
        $this->createdAt = $createdAt;

        return $this;
    }

    public function getModifiedAt()
    {
        return $this->modifiedAt;
    }

    public function setModifiedAt(\DateTimeInterface $modifiedAt): PublishedInfoEntityInterface
    {
        $this->modifiedAt = $modifiedAt;

        return $this;
    }

    /**
     * @return User
     */
    public function getCreatedBy()
    {
        return $this->createdBy;
    }

    /**
     * @param User $createdBy
     * @return Base
     */
    public function setCreatedBy($createdBy): self
    {
        $this->createdBy = $createdBy;
        return $this;
    }

    /**
     * @return User
     */
    public function getModifiedBy()
    {
        return $this->modifiedBy;
    }

    /**
     * @param User $modifiedBy
     * @return Base
     */
    public function setModifiedBy($modifiedBy): self
    {
        $this->modifiedBy = $modifiedBy;
        return $this;
    }

    /**
     * @return int
     */
    public function getStatus()
    {
        return $this->status;
    }

    /**
     * @param integer $status
     */
    public function setStatus($status): void
    {
        $this->status = $status;
        return $this;
    }
}

---

Create a subscriber class for set automatic createdBy and modifiedBy like this code

<?php

namespace App\EventSubscriber;

use ApiPlatform\Core\EventListener\EventPriorities;
use App\Entity\Base;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Event\ViewEvent;
use Symfony\Component\HttpKernel\KernelEvents;
use Symfony\Component\Security\Core\Security;

class AuthoredEntitySubscriber implements EventSubscriberInterface
{
    private $entityManager;
    /**
     * @var Security
     */
    private $security;

    public function __construct(EntityManagerInterface $entityManager,Security $security)
    {
        $this->entityManager = $entityManager;
        $this->security = $security;
    }

    public static function getSubscribedEvents()
    {
        return [KernelEvents::VIEW => ['setAuthor', EventPriorities::PRE_WRITE]];
    }

    public function setAuthor(ViewEvent $event)
    {
        $entity = $event->getControllerResult();
        $method = $event->getRequest()->getMethod();
        $role = $this->security->getToken()->getRoleNames();

        if (!$entity instanceof Base || !in_array($method, [Request::METHOD_POST, Request::METHOD_PUT]) || !$role) {
            return;
        }

         $entity->setModifiedBy($this->security->getUser());

         if (Request::METHOD_POST === $method) {
             $entity->setCreatedBy($this->security->getUser());
         }
    }
}

---

If you want to add automatic createdAt and modifiedAt you must create a interface class named PublishedInfoEntityInterface for createdAt and modifiedAt and this class write this code:

<?php

namespace App\Entity;

interface PublishedInfoEntityInterface
{
    public function setCreatedAt(\DateTimeInterface $dateTime): PublishedInfoEntityInterface;

    public function setModifiedAt(\DateTimeInterface $dateTime): PublishedInfoEntityInterface;
}

---

and create an subscriber for automatic fill createdAt and modifiedAt like this

<?php

namespace App\EventSubscriber;


use ApiPlatform\Core\EventListener\EventPriorities;
use App\Entity\PublishedInfoEntityInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Event\ViewEvent;
use Symfony\Component\HttpKernel\KernelEvents;

class PublishedInfoEntitySubscriber implements EventSubscriberInterface
{

    public static function getSubscribedEvents()
    {
        return [KernelEvents::VIEW => ['setDataTime', EventPriorities::PRE_WRITE]];
    }

    public function setDataTime(ViewEvent $event)
    {
        $entity = $event->getControllerResult();
        $method = $event->getRequest()->getMethod();

        if (!$entity instanceof PublishedInfoEntityInterface || !in_array($method, [Request::METHOD_POST, Request::METHOD_PUT])) {
            return;
        }

        $entity->setCreatedAt(new \DateTime());

        if (Request::METHOD_POST === $method){
            $entity->setModifiedAt(new \DateTime());
        }
    }
}

Finally each class you want to have those property you just extend this class like this

class User extends Base implements UserInterface

And create a migration,