Little return type confusion in LoadClassMetadataEventArgs

[mayerni]

Hi,

i'm on Symfony 6.4 with Doctrine ORM Bundle. I hope I have the right place to discuss my problem.

I'm currently creating an event listener and hook up to doctrine.event_listener.loadClassMetadata with accessing class Doctrine\ORM\Event\LoadClassMetadataEventArgs. Simplified i make this:

namespace App\EventListener;

use Doctrine\ORM\Event\LoadClassMetadataEventArgs;

class MyOrmEventListener
{
    [...]
    /**
     * @param \Doctrine\ORM\Event\LoadClassMetadataEventArgs $eventArgs
     *
     * @return void
     */
    public function loadClassMetadata(LoadClassMetadataEventArgs $eventArgs): void
    {
        $classMetadata = $eventArgs->getClassMetadata();
        [...]
    }
}

so far so unspectacular... but i have a problem with the return value from getClassMetadata().

In Doctrine\ORM\Event\LoadClassMetadataEventArgs the class said it will use/return Doctrine\ORM\Mapping\ClassMetadata:

[...]
namespace Doctrine\ORM\Event;

use Doctrine\ORM\EntityManagerInterface;
use Doctrine\ORM\Mapping\ClassMetadata;
use Doctrine\Persistence\Event\LoadClassMetadataEventArgs as BaseLoadClassMetadataEventArgs;

/**
 * Class that holds event arguments for a loadMetadata event.
 *
 * @extends BaseLoadClassMetadataEventArgs<ClassMetadata<object>, EntityManagerInterface>
 */
class LoadClassMetadataEventArgs extends BaseLoadClassMetadataEventArgs
{
[...]

But the class it extends from - which is Doctrine\Persistence\Event\LoadClassMetadataEventArgs - it will use/return Doctrine\Persistence\Mapping\ClassMetadata, which is not was i looking for:

[...]
namespace Doctrine\Persistence\Event;

use Doctrine\Common\EventArgs;
use Doctrine\Persistence\Mapping\ClassMetadata;
use Doctrine\Persistence\ObjectManager;

/**
 * Class that holds event arguments for a loadMetadata event.
 *
 * @template-covariant TClassMetadata of ClassMetadata<object>
 * @template-covariant TObjectManager of ObjectManager
 */
class LoadClassMetadataEventArgs extends EventArgs
{
    /**
     * @var ClassMetadata
     * @psalm-var TClassMetadata
     */
    private $classMetadata;

    [...]

    public function __construct(ClassMetadata $classMetadata, ObjectManager $objectManager)
    {
        $this->classMetadata = $classMetadata;
        $this->objectManager = $objectManager;
    }
[...]

Now I'm a bit confused. How do I get the expected return I need? These classes are not
(fully) interchangeable!? What am I missing? What am I doing wrong?

Thanks for your help.

[mbabker]

You should have no issues with this.

Yes, the base event class in the doctrine/persistence package expects the base ClassMetadata object. But, the event class also defines generics which will tell anything reading those that if you pass the ORM's event subclass that the event's getClassMetadata() method returns the ORM's ClassMetadata (similar for the getObjectManager() method and specifying whether the ORM's EntityManagerInterface or the generic ObjectManager is provided).

If something is still groaning about it, you can just add an inline assert($classMetadata instanceof ORMClassMetadata) call or an inline docblock for it (I know sometimes PhpStorm doesn't always give the right type info from generics, not sure how well other IDEs support them, so a lot of my code still has those docblocks even though they aren't really needed anymore for any other tooling).

[mayerni]

Hello,

many thanks for the answer. The problem I had wasn't that my IDE was giving me something wrong, but rather that I couldn't access the methods "getAssociationMappings()" and "isInheritanceTypeSingleTable" or, more precisely, that PHP throw me a "method not found" error on make:migration.

But now, I got it to work without consciously changing anything, I think.

Sometimes you should just call it a day.

I apologize for the inconvenience.

Thanks alot. :) I will close this.