Symfony 2 denormalization of nested objects with custom denormalizers

Question

Here I'm building Symfony SDK for REST API. Most of data are JSON objects with nested other JSON objects. Like here

{
    "id": "eng_pl",
    "name": "Premier League",
    "_links": {
        "self": {
            "href": "/tournaments/eng_pl"
        },
        "seasons": {
            "href": "/tournaments/eng_pl/seasons/"
        }
    },
    "coverage": {
        "id": "eng",
        "name": "England",
        "_links": {
            "self": {
                "href": "/territories/eng"
            }
        }
    }
}

Deserialization must produce an object equal to object produced by the code listed below:

$tournament = new Tournament();
$tournament->setId('eng_pl');
$tournament->setName('Premier League');

$coverage = new Territory();
$coverage->setId('eng');
$coverage->setName('England');

$tournament->setCoverage($coverage);

I'm using my own custom Denormalizers, below the fragment of code of denormalizer for Tournament objects:

class TournamentDenormalizer implements DenormalizerInterface
{

    /**
     * @inheritdoc
     */
    public function supportsDenormalization($object, $type, $format = null)
    {

        if ($type != Tournament::class) {
            return false;
        }
        return true;
    }

    /**
     * @inheritdoc
     * @return Tournament
     */
    public function denormalize($object, $class, $format = null, array $context = array())
    {
        $tournament = new Tournament();
        $tournament->setId($object->id);
        $tournament->setName($object->name);

        if (isset($object->coverage)) {
            /** @var Territory $coverage */
            $coverage = ???; //HOWTO how to implement Territory denormalization here???
            $tournament->setCoverage(
                $coverage
            );
        }
            return $tournament;
    }
}

The question is how should I access TerritoryDenormalizer inside TournamentDenormalizer? I see two options:

First one (I'm using now) is to add implements DenormalizerAwareInterface to signature of denormalizer class and rely on Symfony\Component\Serializer\Serializer class:

$serializer = new Symfony\Component\Serializer\Serializer(
    [
        new TournamentDenormalizer(),
        new TerritoryDenormalizer()
    ], [
        new Symfony\Component\Serializer\Encoder\JsonDecode()
    ]
);
$serializer->deserialize($json, Tournament::class, 'json');

So in TournamentDeserializer it will be like here:

if (isset($object->coverage)) {
        /** @var Territory $coverage */
        $coverage = $this->denormalizer->denormalize(
            $object->coverage,
            Territory::class,
            $format,
            $context
        );
        $tournament->setCoverage(
            $coverage
        );
    }
}

The second approach Is to inject necessary denormalizers explicitly

$tournamentDenormalizer = new TournamentDenormalizer();
$tournamentDenormalizer->setTerritoryDenormalizer(new TerritoryDenormalizer());

So in TournamentDeserializer it will be like here:

if (isset($object->coverage)) {
        /** @var Territory $coverage */
        $coverage = $this->territoryDenormalizer->denormalize(
            $object->coverage,
            Territory::class,
            $format,
            $context
        );
        $tournament->setCoverage(
            $coverage
        );
    }
}

Which of approaches is the best? What alternative approaches are possible?

Answer 1

Making your normalizer implement NormalizerAwareInterface (and eventually use NormalizerAwareTrait) is the way to go, this interface has been introduced for this specific use case.