hasOne relation and delete foreign relation not working

[Mikikou]

Hi 👋 I'm working with Phalcon 4 and PHP 7.4

I've got two models

A realty (a real estate property)

class Realty
{
    /**
     * @Primary
     * @Identity
     */
    public ?int $id = null;
    public float $price;

    public function initialize()
    {
        parent::initialize();
        $this->hasOne(
            'id,
            RealtyMetadata::class,
            'realtyId',
            ['alias' => 'Metadata']
        );
    }
}

and the realty optional metadatas

class RealtyMetadata
{
    /**
     * @Primary
     * @Identity
     */
    public ?int $id = null;

    public int $realtyId;

    /**
     * @var array|string $metadata
     */
    public $metadata;

    public function initialize()
    {
        parent::initialize();
        $this->belongsTo(
            'realtyId,
            Realty::class,
            'id',
            ['alias' => 'Realty']
        );
    }
}

I'm implementing an API : PUT realty/:id

let's say I do :

curl --location --request PUT 'http://www.mywebsite.com/realties/1' \
--header 'Content-Type: text/plain' \
--data-raw '{
    "price":150000.0,
    "metadata":null
}'

then in my manager I would do

    public function update(Realty $realty, array $params) : Realty
    {
        if (array_key_exists('metadata', $params)) {
            $metadata = $realty->getMetadata();
            if ($metadata && empty($params['metadata'])) {
                $metadata->delete();
                // $realty->getMetadata(); // it's working only if we do that ! fetching the data again
            } elseif ($metadata) {
                (new MetadataManager())->update($metadata, $params['metadata']);
            } else {
                (new MetadataManager())->create(bla bla bla);
            }
            unset($params['metadata']);
        }
        $realty
            ->assign($params)
            ->save(); // at saving, the metadata is recreated even if previously deleted, unless I uncomment previous comment

        return $realty;
    }

I tried to debug with unit tests with multiple ways. Only two are working :

• the one commented, by fetching $realty->getMetadata( ) without even assigning it to anything
• or after $metadata->delete(), I re-fetch de initial realty : $realty = Realty::findFirst($realty->id);

PS : ->refresh() won't do it, $realty->getMetadata()->delete() won't do it, $realty->Metadata = null; nope, etc.

💡 I get that Phalcon keep relations stored, etc. and that's why at save it might recreate it, even if it's really confusing. So I'm just wondering what is the best way to do that type of operation in your opinion.

the unit test, just in case :

 public function testUpdateDeleteMetadata() : void
    {
        $realty = Realty::findFirst(1);
        $payload = [
            'metadata' => [],
        ];
        $res = $this->realtyManager->update($realty, $payload);
        static::assertNull($res->getMetadata());
    }

thank you for your advice 👍