Doctrine HasOneThrough relation example (based on Laravel Eloquent HasOneThrough)

Car.php

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping\Column;
use Doctrine\ORM\Mapping\Entity;
use Doctrine\ORM\Mapping\GeneratedValue;
use Doctrine\ORM\Mapping\Id;
use Doctrine\ORM\Mapping\JoinColumn;
use Doctrine\ORM\Mapping\OneToOne;

#[Entity()]
class Car
{
    #[Id(), GeneratedValue()]
    private int $id;

    #[Column(name: 'name', type: 'string')]
    private string $name;

    #[OneToOne(inversedBy: 'car', targetEntity: Mechanic::class)]
    #[JoinColumn(name: 'mechanic_id', referencedColumnName: 'id')]
    private Mechanic $mechanic;

    /** Magic to Mechanic#HasOneThrough */
    #[OneToOne(mappedBy: 'car', targetEntity: Owner::class)]
    private Owner $owner;

    public function getId(): int
    {
        return $this->id;
    }

    public function getName(): string
    {
        return $this->name;
    }

    public function setName(string $name): self
    {
        $this->name = $name;

        return $this;
    }

    public function getMechanic(): Mechanic
    {
        return $this->mechanic;
    }

    public function setMechanic(Mechanic $mechanic): self
    {
        $this->mechanic = $mechanic;

        return $this;
    }

    public function getOwner(): Owner
    {
        return $this->owner;
    }
}

CarRepository.php

<?php

namespace App\Repository;

use App\Entity\Mechanic;
use Doctrine\ORM\EntityRepository;

class CarRepository extends EntityRepository
{
    /**
     * @return Mechanic[] 
     * @throws \InvalidArgumentException 
     * @throws \RuntimeException 
     * @throws \Doctrine\ORM\ORMException 
     */
    public function getAllMechanics()
    {
        return $this->createQueryBuilder('m')
            ->from(Mechanic::class, 'm')
            ->getQuery()
            ->getResult();
    }
}

example.php

<?php

use App\Entity\Car;
use App\Repository\CarRepository;
use Doctrine\ORM\EntityManager;

/** @var EntityManager $m */
$em;

/** @var CarRepository $carRepository */
$carRepository = $em->getRepository(Car::class);

// Get all mechanics and car `Owner` through virtual relation `Car`
$allMechanics = $carRepository->getAllMechanics();

foreach ($allMechanics as $mechanic) {
    $carOwner = $mechanic->getCarOwner();
    echo $carOwner->getName() . PHP_EOL;
}

Mechanic.php

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping\Column;
use Doctrine\ORM\Mapping\Entity;
use Doctrine\ORM\Mapping\GeneratedValue;
use Doctrine\ORM\Mapping\Id;
use Doctrine\ORM\Mapping\OneToOne;

#[Entity()]
class Mechanic
{
    #[Id(), GeneratedValue()]
    private int $id;

    #[Column(name: 'name', type: 'string')]
    private string $name;

    /** Magic to Mechanic#HasOneThrough */
    #[OneToOne(mappedBy: 'mechanic', targetEntity: Car::class)]
    private Car $car;

    public function getId(): int
    {
        return $this->id;
    }

    public function getName(): string
    {
        return $this->name;
    }

    public function setName(string $name): self
    {
        $this->name = $name;

        return $this;
    }

    public function getCar(): Car
    {
        return $this->car;
    }

    /**
     * Where the magic happens
     * HasOneThrough 
     */
    public function getCarOwner(): Owner
    {
        return $this->car->getOwner();
    }
}

Owner.php

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping\Column;
use Doctrine\ORM\Mapping\Entity;
use Doctrine\ORM\Mapping\GeneratedValue;
use Doctrine\ORM\Mapping\Id;
use Doctrine\ORM\Mapping\JoinColumn;
use Doctrine\ORM\Mapping\OneToOne;

#[Entity()]
class Owner
{
    #[Id(), GeneratedValue()]
    private int $id;

    #[Column(name: 'name', type: 'string')]
    private string $name;

    #[OneToOne(inversedBy: 'owner', targetEntity: Car::class)]
    #[JoinColumn(name: 'car_id', referencedColumnName: 'id')]
    private Car $car;

    public function getId(): int
    {
        return $this->id;
    }

    public function getName(): string
    {
        return $this->name;
    }

    public function setName(string $name): self
    {
        $this->name = $name;

        return $this;
    }

    public function getCar(): Car
    {
        return $this->car;
    }

    public function setCar(Car $car): self
    {
        $this->car = $car;

        return $this;
    }
}