Association lazy-loading with Zend\Db

BlogPostHydrator.php

<?php

use ProxyManager\Factory\LazyLoadingValueHolderFactory;
use Zend\Stdlib\Hydrator\HydratorInterface;

class BlogPostHydrator implements HydratorInterface
{
    /**
     * @var HydratorInterface
     */
    private $wrappedHydrator;

    /**
     * @var UserTable
     */
    private $userTable;

    /**
     * @var LazyLoadingValueHolderFactory
     */
    private $proxyFactory;

    public function __construct(
        HydratorInterface $wrappedHydrator,
        UserTable $userTable,
        LazyLoadingValueHolderFactory $proxyFactory
    ) {

        $this->wrappedHydrator = $wrappedHydrator;
        $this->userTable       = $userTable;
        $this->proxyFactory    = $proxyFactory;
    }

    /**
     * {@inheritDoc}
     */
    public function extract($object)
    {
        // ... not covered in this example
    }

    /**
     * {@inheritDoc}
     */
    public function hydrate(array $data, $object)
    {
        if (isset($data['author_id'])) {
            $data['author'] = $this->buildAuthorProxy($data['author_id']);
        }

        return $this->wrappedHydrator->hydrate($data, $object);
    }

    private function buildAuthorProxy($id)
    {
        $this->proxyFactory->createProxy(
            'User',
            function (& $wrappedObject, $proxy, $method, $parameters, & $initializer) use ($id) {
                $initializer   = null;
                $wrappedObject = $this->userTable->findUser($id);

                return true;
            }
        );
    }
}

usage.php

<?php

use ProxyManager\Factory\LazyLoadingValueHolderFactory;

$blogPostHydrator = new BlogPostHydrator(new ClassMethods(), $userTable, new LazyLoadingValueHolderFactory());

$data = [
    'title'     => 'Stuff',
    'content'   => 'Lorem ipsum dolor....',
    'author_id' => 123, 
];

$blogPost = $blogPostHydrator->hydrate($data, new BlogPost());