Adding domains and hosting services.

ItemResolver.php

<?php

namespace App\Bundle\AppBundle\Resolver;

use App\Bundle\AppBundle\Entity\Domain;
use Doctrine\Common\Persistence\ObjectRepository;
use Sylius\Bundle\CartBundle\Model\CartItemInterface;
use Sylius\Bundle\CartBundle\Resolver\ItemResolverInterface;
use Sylius\Bundle\CartBundle\Resolver\ItemResolvingException;
use Symfony\Component\HttpFoundation\Request;

class CartItemResolver implements ItemResolverInterface
{
    private $domainRepository;
    private $hostingRepository;

    public function __construct(ObjectRepository $domainRepository, ObjectRepository $hostingRepository)
    {
        $this->domainRepository = $domainRepository;
        $this->domainRepository = $domainRepository;
    }

    public function resolve(CartItemInterface $item, Request $request)
    {
        if (null !== $hostingId = $request->get('hostingId')) {
            return $this->resolveHosting($hostingId, $item, $request);
        }

        if (null !== $domain = $request->get('domain')) {
            return $this->resolveDomain($domain, $item, $request);
        }

        throw new ItemResolvingException('Error occured while adding item to cart');
    }

    private function resolveHosting($id, CartItemInterface $item, Request $request)
    {
        if (!$hosting = $this->hostingRepository->find($id)) {
            throw new ItemResolvingException('Requested hosting plan is not available');
        }

        $item->setHosting($hosting);
        $item->setUnitPrice($hosting->getPrice());

        return $item;
    }

    private function resolveDomain($name, CartItemInterface $item, Request $request)
    {
        $domain = $this->domainRepository->findOrCreate($name);

        $item->setDomain($domain);
        $item->setUnitPrice($this->getDomainPrice($domain);

        return $item;
    }
    
    private function getDomainPrice(Domain $domain)
    {
        return 19.99; // Some your own logic here to determine the price for domain. 
    }
}