Request Handler with Validation for PHP projects

src_Controller_SampleController.php

<?php declare(strict_types=1);

namespace Api\Controller;

use Api\Model\User\TokenDTO;
use Api\RequestValidator\RequestHandler;
use Api\RequestValidator\Security\RefreshTokenRequestValidator;
use Api\RequestValidator\ValidationFailed;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;

final class SampleController extends Controller
{
    /**
     * @Route(methods={"POST"})
     */
    public function refreshTokenAction(Request $request, RequestHandler $handler): Response
    {
        try {
            /** @var TokenDTO $dto */
            $dto = $handler->handle($request, new RefreshTokenRequestValidator());
        } catch (ValidationFailed $e) {
            return $this->json([
                'error' => [
                    'message' => $e->getMessage(),
                    'violations' => $e->getViolations(), // FIXME: Change ConstraintViolationsList to array
                ],
            ], Response::HTTP_UNPROCESSABLE_ENTITY);
        }
        
        // DO some stuff with DTO
        
        return $this->json(['data' => true], Response::HTTP_OK);
    }
}

src_RequestValidator_RequestHandler.php

<?php declare(strict_types=1);

namespace Api\RequestValidator;

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Validator\Validator\ValidatorInterface;

class RequestHandler
{
    private $validator;

    public function __construct(ValidatorInterface $validator)
    {
        $this->validator = $validator;
    }

    public function handle(Request $request, RequestValidatorInterface $requestValidator): object
    {
        $data = $request->request->all();
        $violations = $this->validator->validate($data, $requestValidator->getRules());
        if ($violations->count()) {
            throw new ValidationFailed($violations);
        }

        return $requestValidator->prepareModel($data);
    }
}

src_RequestValidator_RequestValidatorInterface.php

<?php declare(strict_types=1);

namespace Api\RequestValidator;

use Symfony\Component\Validator\Constraints\Collection;

interface RequestValidatorInterface
{
    public function getRules(): Collection;
    public function prepareModel(array $data): object;
}

src_RequestValidator_ValidationFailed.php

<?php declare(strict_types=1);

namespace Api\RequestValidator;

use Symfony\Component\Validator\ConstraintViolationListInterface;

class ValidationFailed extends \RuntimeException
{
    private $violationList;

    public function __construct(ConstraintViolationListInterface $violationList)
    {
        $this->violationList = $violationList;
        parent::__construct('Validation failed.');
    }
  
    public function getViolations(): ConstraintViolationListInterface
    {
        return $this->violationList;
    }
}

src_RequestValidator_Validator_SampleRequestValidator.php

<?php declare(strict_types=1);

namespace Api\RequestValidator\Validator;

use Api\Model\TokenDTO;
use Api\RequestValidator\RequestValidatorInterface;
use Symfony\Component\Validator\Constraints as Assert;

class SampleRequestValidator implements RequestValidatorInterface
{
    public function getRules(): Assert\Collection
    {
        return new Assert\Collection([
            'token' => [
                new Assert\NotBlank(),
            ],
        ]);
    }

    public function prepareModel(array $data): object
    {
        return new TokenDTO($data['token']);
    }
}