[VarExporter][DoctrineBundle] Accessing unknown properties on lazy ghost objects generates notices instead exceptions

[kiler129]

Symfony version(s) affected

6.2.4

Description

Initially this bug looked like an issue with EasyAdmin Bundle, as it is triggered by its code. The simplest way to do it is to add a field which doesn't exist on an entity, e.g.:

        yield TextField::new('type.thresholds_matches', 'Thresholds')
                       ->setVirtual(true)
                       ->setTemplatePath('admin/field/measurement_threshold.html.twig');

When enable_lazy_ghost_objects is disabled this works correctly and simply renders an empty field/custom template. However, the issue isn't actually in EAB but in LazyGhostTrait breaking the PropertyAccessorInterface promise:

symfony/src/Symfony/Component/PropertyAccess/PropertyAccessorInterface.php

Lines 69 to 74 in 991c2ba

	* @throws Exception\InvalidArgumentException If the property path is invalid
	* @throws Exception\AccessException If a property/index does not exist or is not public
	* @throws Exception\UnexpectedTypeException If a value within the path is neither object
	* nor array
	*/
	public function getValue(object|array $objectOrArray, string|PropertyPathInterface $propertyPath): mixed;

->getValue() should produce an exception when a given property doesn't exist, which EAB relies on: https://github.com/EasyCorp/EasyAdminBundle/blob/4db1860871809ca0be610ba5dab9be26ba165351/src/Field/Configurator/CommonPreConfigurator.php#L49-L53

How to reproduce

PoC reproducer, pick your own entity of course. In my case the type field is configured as:

    #[ORM\ManyToOne]
    #[ORM\JoinColumn(nullable: false)]
    private ?MeasurementType $type = null;

The test code I used:

<php declare(strict_types=1);

#[AsCommand(name: 'app:sandbox')]
class SandboxCommand extends Command
{
    public function __construct(private ManagerRegistry $doctrine, private PropertyAccessorInterface $propertyAccessor)
    {
        parent::__construct();
    }

    protected function execute(InputInterface $input, OutputInterface $output): int
    {
        $repo = $this->doctrine->getRepository(InanimateObjectMeasurement::class);
        $ent = $repo->findOneBy([]);

        dump($ent);
        dump($this->propertyAccessor->getValue($ent, 'value'));
        dump($this->propertyAccessor->getValue($ent, 'type.thresholds_matches'));
        
        return 0;
    }

With enable_lazy_ghost_objects=false:

 % bin/console app:sandbox -v
"183/88"

In PropertyAccessor.php line 453:
                                                                                                                               
  [Symfony\Component\PropertyAccess\Exception\NoSuchPropertyException]                                                         
  Can't get a way to read the property "thresholds_matches" in class "Proxies\__CG__\App\Entity\Measurement\MeasurementType". 

With enable_lazy_ghost_objects=true:

 % bin/console app:sandbox -v
"183/88"

In LazyGhostTrait.php line 191:
                                                                                                                                                                                                                                       
  [ErrorException]                                                                                                                                                                                                                     
  User Notice: Undefined property: Proxies\__CG__\App\Entity\Measurement\MeasurementType::$thresholds_matches in /app/vendor/symfony/property-access/PropertyAccessor.php on line 428  
                                                                                                                                                                                                                                       

Possible Solution

No response

Additional Context

No response

[nicolas-grekas]

LazyGhostTrait cannot break the contract of PropertyAccessorInterface because it is not bound by the contract.
The issue is either in PropertyAccessor being too confident in having a __get meaning the property is reachable, or in easy admin relying on it while it shouldn't (why does a virtual field get fetched on a property?)

Anyway, can you please provide a repository with the working reproducer? That'd help a lot. Thanks.

[nicolas-grekas]

/cc @javiereguiluz WDYT of my previous comment about easy admin?

[nickygerritsen]

We also run into this if you call $propertyAccessor->isReadable on a property that doesn't exist on a 'ghosted' Doctrine entity, you get this error. Not sure if it happens in general, but at least it happens here: https://github.com/DOMjudge/domjudge/blob/symfony-62/webapp/src/Controller/Jury/TeamController.php#L122 (note that on that branch lazy ghost objects are disabled since this would break our CI).

This is the backtrace for that error by the way:

ErrorException:
User Notice: Undefined property: Proxies\__CG__\App\Entity\Team::$num_contests in /domjudge/lib/vendor/symfony/property-access/PropertyAccessor.php on line 428

  at /domjudge/lib/vendor/symfony/var-exporter/LazyGhostTrait.php:193
  at Proxies\__CG__\App\Entity\Team->__get()
     (/domjudge/lib/vendor/symfony/property-access/PropertyAccessor.php:428)
  at Symfony\Component\PropertyAccess\PropertyAccessor->readProperty()
     (/domjudge/lib/vendor/symfony/property-access/PropertyAccessor.php:330)
  at Symfony\Component\PropertyAccess\PropertyAccessor->readPropertiesUntil()
     (/domjudge/lib/vendor/symfony/property-access/PropertyAccessor.php:227)
  at Symfony\Component\PropertyAccess\PropertyAccessor->isReadable()
     (src/Controller/Jury/TeamController.php:122)
  at App\Controller\Jury\TeamController->indexAction()
     (/domjudge/lib/vendor/symfony/http-kernel/HttpKernel.php:163)
  at Symfony\Component\HttpKernel\HttpKernel->handleRaw()
     (/domjudge/lib/vendor/symfony/http-kernel/HttpKernel.php:74)
  at Symfony\Component\HttpKernel\HttpKernel->handle()
     (/domjudge/lib/vendor/symfony/http-kernel/Kernel.php:184)
  at Symfony\Component\HttpKernel\Kernel->handle()
     (/domjudge/lib/vendor/symfony/runtime/Runner/Symfony/HttpKernelRunner.php:35)
  at Symfony\Component\Runtime\Runner\Symfony\HttpKernelRunner->run()
     (/domjudge/lib/vendor/autoload_runtime.php:30)
  at require_once('/domjudge/lib/vendor/autoload_runtime.php')
     (public/index.php:5)  

[delboy1978uk]

We are upgrading a site to Symfony 6.3, we were using reflection in one of our classes to access the Connection class of an EntityManager, but now that fails because we do not have the real object and have this uninitialised lazy ghost instead. Any ideas?

[nicolas-grekas]

@kiler129 could you please wrap your reproducer into a repository to help me bootstrap this quickly?

[nickygerritsen]

I have a very minimal repo to reproduce this for my case. It comes down to:

        $p    = PropertyAccess::createPropertyAccessor();
        $item = new \Proxies\__CG__\App\Entity\Item();
        $item->setName('test');
        dump($item);
        dump($p->isReadable($item, 'name')); // <-- Works
        dump($p->isReadable($item, 'missing')); // <-- Gives a notice

Repo can be found here.

Switching lazy ghost objects off makes this code work without a notice.

Let me know if you need anything else from me. My guess is this issue also resolves the original one.

[nicolas-grekas]

Should be fixed by #54194