[Validator] Allow using attributes to declare compile-time constraint metadata #61528

nicolas-grekas · 2025-08-26T06:53:59Z

Q	A
Branch?	7.4
Bug fix?	no
New feature?	yes
Deprecations?	no
Issues	-
License	MIT

Prerequisite for #61288

At the moment, validation attributes are read at runtime when framework.validation.enable_attributes is true.

This means they don't fit for bundles nor can't they be warmed up.

This PR fixes both issues by using a new validator.attribute_metadata resource tag, that's turned into a list of classes to parse for attributes at compile-time.

For apps, the tag is added by autoconfiguration: any Constraint-derived attributes found on a class in the src/ folder will trigger the rule to add the tag.

For bundles (and for apps if they want to), the tag is added by explicit service configuration. In an "eat your own dog-food" spirit, this capability is used to declare the constraints of the Form class: instead of loading the validation.xml file, we now declare this service resource:

        ->set('validator.form.attribute_metadata', Form::class)
            ->tag('container.excluded')
            ->tag('validator.attribute_metadata')

This reads the attributes added to the Form class:

#[AssertForm()]
#[Traverse(false)]
class Form implements \IteratorAggregate, FormInterface, ClearableErrorsInterface

Bundles can do the same and replace their XML files by attributes.

As a next step, we could also deprecate runtime-discovery of attributes. This could be worth it if this discovery has a measurable performance impact. To be measured if one wants to dig this idea.

Side note: I'm hoping this could allow removing the yaml and xml config formats one day. For serialization metadata also (PR coming). BUT, this doesn't (yet) cover the use case of overriding metadata defined by bundles. For that, apps still have to use xml or yaml in config/validation/. I have an idea to cover this, coming to a next PR if it works.

(failures unrelated)

src/Symfony/Component/Validator/DependencyInjection/AttributeMetadataPass.php

src/Symfony/Component/Form/Extension/Validator/Constraints/Form.php

src/Symfony/Component/Form/Form.php

src/Symfony/Component/Validator/DependencyInjection/AttributeMetadataPass.php

… metadata

stof · 2025-08-29T11:05:42Z

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

+        if (!ContainerBuilder::willBeAvailable('symfony/form', Form::class, ['symfony/framework-bundle', 'symfony/validator'])) {
+            $container->removeDefinition('validator.form.attribute_metadata');
+        } elseif (!($r = new \ReflectionClass(Form::class))->getAttributes(Traverse::class) || !class_exists(ValidatorAttributeMetadataPass::class)) {
+            $fileRecorder('xml', \dirname($r->getFileName()).'/Resources/config/validation.xml');


I suggest adding a comment that this is for symfony/form < 7.4 or symfony/validator < 7.4, to make it easier to clean this code when bumping the min version of those packages supported in FrameworkBundle (which will likely happen at some point during the 8.x lifecycle)

stof · 2025-08-29T11:15:39Z

src/Symfony/Component/Validator/Constraint.php

@@ -27,6 +27,7 @@
 *
 * @author Bernhard Schussek <bschussek@gmail.com>
 */
+#[\Attribute(\Attribute::TARGET_CLASS | \Attribute::TARGET_PROPERTY | \Attribute::TARGET_METHOD | \Attribute::IS_REPEATABLE)]


Why adding this here ? The abstract class cannot be used as an attribute. And child classes defining concrete constraints will have to specify the proper target anyway.

It's required by the engine in relation to registerAttributeForAutoconfiguration

GromNaN · 2025-08-29T11:33:35Z

src/Symfony/Bundle/FrameworkBundle/CacheWarmer/ValidatorCacheWarmer.php

     */
    private function extractSupportedLoaders(array $loaders): array
    {
        $supportedLoaders = [];

        foreach ($loaders as $loader) {
-            if ($loader instanceof XmlFileLoader || $loader instanceof YamlFileLoader) {
+            if (method_exists($loader, 'getMappedClasses')) {


This method existence should be checked using an interface. For compatibility with older versions of the validator component, we can keep checking the concrete classes.

Suggested change

if (method_exists($loader, 'getMappedClasses')) {

if ($loader instanceof XmlFileLoader || $loader instanceof YamlFileLoader || $loader instanceof WarmableLoaderInterface)

src/Symfony/Bundle/FrameworkBundle/CacheWarmer/ValidatorCacheWarmer.php

GromNaN · 2025-08-29T11:40:01Z

src/Symfony/Bundle/FrameworkBundle/CacheWarmer/ValidatorCacheWarmer.php

            } elseif ($loader instanceof LoaderChain) {
                $supportedLoaders = array_merge($supportedLoaders, $this->extractSupportedLoaders($loader->getLoaders()));


The LoaderChain can implement the getMappedClasses method, so that we can remove this specific case in 8.0, once validator 7.4+ is required.

I think all this is pretty much internal, I'm not sure adding an interface and the rest is worth it.

This makes the intention clearer and the code more understandable and statically analyzable.

I'd really prefer not opening a new abstraction. Nobody asked for any while this code exists since years...

nicolas-grekas requested review from xabbuh and yceruto as code owners August 26, 2025 06:54

carsonbot added Status: Needs Review Feature Validator labels Aug 26, 2025

carsonbot added this to the 7.4 milestone Aug 26, 2025

nicolas-grekas force-pushed the validator.attribute_metadata branch 3 times, most recently from 289783f to 8be45c5 Compare August 26, 2025 08:37

nicolas-grekas changed the title ~~[Validator] Allow using attributes on classes as constraint metadata configuration~~ [Validator] Allow using attributes to declare compile-time constraint metadata Aug 26, 2025

nicolas-grekas force-pushed the validator.attribute_metadata branch 3 times, most recently from defd051 to ea317e8 Compare August 26, 2025 16:01

nicolas-grekas mentioned this pull request Aug 26, 2025

[Serializer] Allow using attributes to declare compile-time serialization metadata #61532

Open

nicolas-grekas force-pushed the validator.attribute_metadata branch 2 times, most recently from d3490c8 to 9d08608 Compare August 27, 2025 10:05

xabbuh reviewed Aug 27, 2025

View reviewed changes

src/Symfony/Component/Validator/DependencyInjection/AttributeMetadataPass.php Show resolved Hide resolved

nicolas-grekas force-pushed the validator.attribute_metadata branch 2 times, most recently from 3dc6ebf to 35c205e Compare August 27, 2025 12:41

GromNaN reviewed Aug 27, 2025

View reviewed changes

nicolas-grekas force-pushed the validator.attribute_metadata branch from 35c205e to 325c0c3 Compare August 27, 2025 12:59

[Validator] Allow using attributes to declare compile-time constraint…

cd349b8

… metadata

nicolas-grekas force-pushed the validator.attribute_metadata branch from 325c0c3 to cd349b8 Compare August 28, 2025 08:08

nicolas-grekas mentioned this pull request Aug 28, 2025

[Validator] Add #[ValidationFor] to declare new constraints for a class #61545

Open

stof reviewed Aug 29, 2025

View reviewed changes

stof mentioned this pull request Aug 29, 2025

[Validator] Deprecate XML configuration format #61288

Open

GromNaN reviewed Aug 29, 2025

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Uh oh!

[Validator] Allow using attributes to declare compile-time constraint metadata #61528

[Validator] Allow using attributes to declare compile-time constraint metadata #61528

nicolas-grekas commented Aug 26, 2025 •

edited

Loading

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

stof Aug 29, 2025

Uh oh!

stof Aug 29, 2025

Uh oh!

nicolas-grekas Aug 29, 2025

Uh oh!

GromNaN Aug 29, 2025

Uh oh!

Uh oh!

GromNaN Aug 29, 2025

Uh oh!

nicolas-grekas Aug 29, 2025

Uh oh!

GromNaN Aug 29, 2025

Uh oh!

nicolas-grekas Aug 29, 2025

Uh oh!

Uh oh!

	if (method_exists($loader, 'getMappedClasses')) {
	if ($loader instanceof XmlFileLoader \|\| $loader instanceof YamlFileLoader \|\| $loader instanceof WarmableLoaderInterface)

		} elseif ($loader instanceof LoaderChain) {
		$supportedLoaders = array_merge($supportedLoaders, $this->extractSupportedLoaders($loader->getLoaders()));

Uh oh!

[Validator] Allow using attributes to declare compile-time constraint metadata #61528

Are you sure you want to change the base?

[Validator] Allow using attributes to declare compile-time constraint metadata #61528

Conversation

nicolas-grekas commented Aug 26, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

nicolas-grekas commented Aug 26, 2025 •

edited

Loading