API Platform version(s) affected: 3.2.18

Description

If a DTO expose a property with a API Resource but this property is typed using an Interface to allow polymorphism: Api Platform won't be able to resolve the final resource' types and will serialize the short className in @type for JsonLd format.

interface CommonResource {

}

#[ApiResource( types: [ 'https://schema.org/Thing' ] )]
class MyResource implements CommonResource {

}

class MyDto {
    #[ApiProperty]
    public ?CommonResource $resource = null;
}


$dto = (new MyDto())->resource = new MyResource();

Actual output:

{
    "@type": "MyDto",
    "resource": {
        "@type": "MyResource"
    }
}

Expected output:

{
    "@type": "MyDto",
    "resource": {
        "@type": "https://schema.org/Thing"
    }
}

Possible cause : \ApiPlatform\JsonLd\Serializer\ItemNormalizer::normalize (line 84)

I think that's because in \ApiPlatform\JsonLd\Serializer\ItemNormalizer::normalize, $context['resource_class'] is populated with the interface CommonResource which is not an ApiResource.

$resourceClass = $this->getObjectClass($object); // Here : MyResource
$previousResourceClass = $context['resource_class'] ?? null; // Here: CommonResource

So this condition cannot be true (line 84), and resource is normalized as an anonymous resource:

if($isResourceClass = $this->resourceClassResolver->isResourceClass($resourceClass) && (null === $previousResourceClass || $this->resourceClassResolver->isResourceClass($previousResourceClass)))
{
    //...
}

Possible solution:

We should test if $previousResourceClass is an interface or abstract class and $resourceClass is an instanceof
$previousResourceClass then build context against $resourceClass, not $previousResourceClass.