zf2 - Nested Aggregate Hydrators - zend-framework2

Question

Is it possible to nest aggregate hydrators? If i have the following classes:
class Appointment{
public date;
public startTime;
public endTime;
public User; //* #var User */
}
class User{
public Location; //* #var Location*/
}
...being populated with the following AggregateHydrator (created from a factory):
class AppointmentModelHydratorFactory implements FactoryInterface
{
public function createService(ServiceLocatorInterface $serviceLocator) {
$serviceManager = $serviceLocator->getServiceLocator();
$arrayHydrator = new ArraySerializable();
$arrayHydrator->addStrategy('date', new DateTimeStrategy())
->addStrategy('endTime', new TimeStrategy())
->addStrategy('startTime', new TimeStrategy());
$aggregateHydrator = new AggregateHydrator();
$aggregateHydrator->add($arrayHydrator);
$aggregateHydrator->add($serviceLocator->get('Hydrator\User'));
return $aggregateHydrator;
}
}
With the UserHydratorFactory looking like:
class UserHydratorFactory implements FactoryInterface
{
public function createService(ServiceLocatorInterface $serviceLocator) {
$sm = $serviceLocator->getServiceLocator();
$userHydrator = new UserHydrator($sm->get('User\Mapper'));
$aggregateHydrator = new AggregateHydrator();
$aggregateHydrator->add($userHydrator );
$aggregateHydrator->add($sm->get('HydratorManager')->get('Hydrator\User\Location'));
return $aggregateHydrator;
}
}
This is throwing an expection as the model is being returned as null, but if i comment out adding the Location hydrator to the User hydrator, it works fine (albeit without location data loaded). So i was wondering if aggregate hydrators are able to be nested?

Answer 1

It is not built-in, but doable.
namespace Hydrator;
use Zend\Stdlib\Hydrator\HydratorInterface;
class NestedHydrator implements HydratorInterface
{
protected $inner_hydrator;
private $empty;
public function __construct ($inner_hydrator, $empty)
{
$this->inner_hydrator = $inner_hydrator;
$this->empty = $empty;
}
public function extract ($object)
{
return [
$this->getPath() => $this->inner_hydrator->extract ($object->{$this->getPath()})
];
}
public function hydrate (array $data, $object)
{
$object->{$this->getPath()} = $this->inner_hydrator->hydrate ($data [$this->getPath()], $this->empty);
return $object;
}
protected function getPath ()
{
return get_class ($this->empty);
}
}
And then:
$u = new User();
$u->Location = "4 Clinton Rd.";
$a = new Appointment();
$a->date = "yesterday";
$a->startTime = "7:00";
$a->endTime = "8:00";
$a->User = $u;
$h = new AggregateHydrator();
$h->add (new ObjectProperty());
$nested = new \Hydrator\NestedHydrator(new ObjectProperty(), new User());
$h->add ($nested);
$data = $h->extract ($a);
$b = $h->hydrate ($data, new Appointment());
$this->assertEquals ($a, $b);