[EventDispatcher] Validate existence of event listener classes #60277

ashutoshagrawal1010 · 2025-04-26T02:15:45Z

Q	A
Branch?	7.3
Bug fix?	no
New feature?	no
Deprecations?	no
Issues	Fix #54095
License	MIT

This PR improves the developer experience for event listener services.

During container compilation, it validates that the service class defined for a kernel.event_listener tag actually exists.
If the class does not exist, it throws an early InvalidArgumentException instead of failing later at runtime.

carsonbot · 2025-04-26T02:15:50Z

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I see that this is your first PR. That is great! Welcome!

Symfony has a contribution guide which I suggest you to read.

In short:

Always add tests
Keep backward compatibility (see https://symfony.com/bc).
Bug fixes must be submitted against the lowest maintained branch where they apply (see https://symfony.com/releases)
Features and deprecations must be submitted against the 7.3 branch.

Review the GitHub status checks of your pull request and try to solve the reported issues. If some tests are failing, try to see if they are failing because of this change.

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If this PR is merged in a lower version branch, it will be merged up to all maintained branches within a few days.

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ashutoshagrawal1010 · 2025-04-26T02:41:55Z

As per my understanding, failed tests are unrelated to my change.

GromNaN

This is something that could potentially be useful for all the classes in the container, not just the event listener. As a last step before dumping the container, we can check the classes used for all services.

This was proposed 10 years ago, but declined: #11315 (comment). This decision may be reviewed.

src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php

…ggest close matches during container compilation

GromNaN · 2025-05-09T08:29:58Z

src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php

@@ -172,10 +172,13 @@ public function process(ContainerBuilder $container)

    private function getEventFromTypeDeclaration(ContainerBuilder $container, string $id, string $method): string
    {
+        $class = $container->getDefinition($id)->getClass();
+        if (!$r = $container->getReflectionClass($class)) {
+            throw new InvalidArgumentException(sprintf('Class "%s" used for service "%s" cannot be found.', $class, $id));


An exception is already thrown by ContainerBuilder::getReflectionClass:

symfony/src/Symfony/Component/DependencyInjection/ContainerBuilder.php

Lines 379 to 386 in fbff277

/**

* Retrieves the requested reflection class and registers it for resource tracking.

*

* @throws \ReflectionException when a parent class/interface/trait is not found and $throw is true

*

* @final

*/

public function getReflectionClass(?string $class, bool $throw = true): ?\ReflectionClass

I could not reproduce this exception with the test in the PR. The ContainerBuilder::getReflectionClass returns null instead of throwing.

GromNaN · 2025-05-09T08:31:02Z

I changed the target branch as this is a behavior change and not a bug.

nicolas-grekas · 2025-05-09T13:48:18Z

👎 for the current implementation but looking at the linked issue, I'm wondering if we shouldn't add the check when the class is not defined for a service (and thus when the id becomes the class). Up for digging this idea @ashutoshagrawal1010?

nicolas-grekas · 2025-05-30T16:23:44Z

Closing meanwhile. Thanks for submitting.

carsonbot added Status: Needs Review Bug EventDispatcher labels Apr 26, 2025

carsonbot added this to the 6.4 milestone Apr 26, 2025

ashutoshagrawal1010 changed the title ~~[EventDispatcher] Validate existence of event listener classes~~ [DependencyInjection] Validate existence of event listener classes Apr 26, 2025

ashutoshagrawal1010 mentioned this pull request Apr 28, 2025

Confusing error message: 'must define the "event" attribute on "kernel.event_listener" tags' when the problem was nonexistent class #54095

Open

GromNaN requested changes Apr 28, 2025

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src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php Outdated Show resolved Hide resolved

carsonbot added Status: Needs Work and removed Status: Needs Review labels Apr 28, 2025

carsonbot changed the title ~~[DependencyInjection] Validate existence of event listener classes~~ [EventDispatcher] Validate existence of event listener classes Apr 28, 2025

GromNaN reviewed Apr 28, 2025

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src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php Outdated Show resolved Hide resolved

ashutoshagrawal1010 requested review from lyrixx, yceruto, chalasr, dunglas, OskarStark, jderusse and xabbuh as code owners April 30, 2025 00:53

carsonbot added Status: Needs Review and removed Status: Needs Work labels Apr 30, 2025

ashutoshagrawal1010 marked this pull request as draft April 30, 2025 00:54

ashutoshagrawal1010 force-pushed the fix-missing-listener-class-validation branch 3 times, most recently from 2b5b852 to 7a8e232 Compare April 30, 2025 01:30

[EventDispatcher] Validate existence of event listener classes and su…

282dc16

…ggest close matches during container compilation

ashutoshagrawal1010 force-pushed the fix-missing-listener-class-validation branch from 7a8e232 to 282dc16 Compare April 30, 2025 01:41

ashutoshagrawal1010 marked this pull request as ready for review April 30, 2025 01:52

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ashutoshagrawal1010 requested a review from GromNaN April 30, 2025 01:52

GromNaN changed the base branch from 6.4 to 7.3 May 9, 2025 08:26

GromNaN reviewed May 9, 2025

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nicolas-grekas closed this May 30, 2025

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[EventDispatcher] Validate existence of event listener classes #60277

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	/**
	* Retrieves the requested reflection class and registers it for resource tracking.
	*
	* @throws \ReflectionException when a parent class/interface/trait is not found and $throw is true
	*
	* @final
	*/
	public function getReflectionClass(?string $class, bool $throw = true): ?\ReflectionClass

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