Problem while hydrating a Doctrine Entity when using an interface as alias.

[pink6440]

• Using symfony 7.3

With Doctrine ORM, when aliasing a concrete class to an interface, the hydratation process does not work anymore.

Doctrine configuration

doctrine:
  orm:
    resolve_target_entities:
      MyInterface: App\Entity\MyRealEntity

In the component

    #[LiveProp()]
    public ?MyInterface $initialFormData = null;

The error

An exception has been thrown during the rendering of a template ("Cannot dehydrate value typed as interface

The workaround

I have a workaround but i'mnot really used about what to do to help, so, guidelines are welcome :)

Digging into DoctrineEntityHydrationExtension.php :

  private function objectManagerFor(string $class): ?ObjectManager
    {
        if (!interface_exists($class) && !class_exists($class)) {
            return null;
        }

        // todo cache/warmup an array of classes that are "doctrine objects"
        foreach ($this->managerRegistries as $registry) {
            foreach($registry->getManagers() as $om) {
                // this way, it resolve the interface
                if ($om->getClassMetadata($class)) {
                    return self::ensureManagedObject($om, $class);
                }
            }
            // does not work with interface
            // if ($om = $registry->getManagerForClass($class)) {
            //    return self::ensureManagedObject($om, $class);
            // }
        }

        return null;
    }

[Kocal]

I'm far from being a Doctrine expert, and at this moment I don't know how we can use this resolve_target_entities setting / Doctrine API to get your MyInterface being correctly hydrated.

As a short solution, I can suggest you to create your own Hydration Extension:

• supports MyInterface
• hydrate from an id to your MyInterface entity
• dehydrate from your MyInterface entity to an id

[pink6440]

Hi Kocal,

I'm agree about create a specific hydrator.

However, it is still possible to make the current doctrine hydrator to work if objectManagerFor method is updated.

First problem to solve : find the object manager wich is responsible for the final entity

$interface = UserInterface::class;

// current method : that won't work
$em = $this->doctrine->getManagerForClass($interface);
$io->writeln("Manager (method 1) : ".($em ? get_class($em) : "not found"));

// second method : that works

foreach($this->doctrine->getManagers() as $em){
    if ($em->getClassMetadata($interface)) {
        // founded !
        $io->writeln("Manager (method 2) : ".get_class($em));
    }

}

Second problem : how to hydrate/dehydrate the entity from the interface
According to the existing code of the doctrine hydrator, it already works.

 public function dehydrate(object $object): mixed
    {
       // if the object manager is resolved, it will provide the right metadata for the final class 
        $id = $this
            ->objectManagerFor($class = $object::class)
            ->getClassMetadata($class)
            ->getIdentifierValues($object)
        ;

And same goes for hydrate process (the find method resolves nicely if using interface)

 public function hydrate(mixed $value, string $className): ?object
    {
        // an empty array means a non-persisted entity
        // we support instantiating with no constructor args
        if (\is_array($value) && 0 === \count($value)) {
            return new $className();
        }

        // e.g. an empty string
        if (!$value) {
            return null;
        }

        // $data is a single identifier or array of identifiers
        if (\is_scalar($value) || \is_array($value)) {
            return $this->objectManagerFor($className)->find($className, $value);
        }

        throw new \InvalidArgumentException(\sprintf('Cannot hydrate Doctrine entity "%s". Value of type "%s" is not supported.', $className, get_debug_type($value)));
    }

[Kocal]

Hi, and thanks for your investigation :)

Do you want to open a PR?

[pink6440]

Thanks you too for the already done work !
And I will try to make the pm.