symfony · nicolas-grekas · Feb 20, 2025 · Feb 18, 2025
diff --git a/src/Symfony/Component/Validator/CHANGELOG.md b/src/Symfony/Component/Validator/CHANGELOG.md
@@ -11,6 +11,7 @@ CHANGELOG
  * Add support for the `otherwise` option in the `When` constraint
  * Add support for multiple fields containing nested constraints in `Composite` constraints
  * Add the `stopOnFirstError` option to the `Unique` constraint to validate all elements
+ * Add support for closures in the `When` constraint
 
 7.2
 ---

diff --git a/src/Symfony/Component/Validator/Constraints/When.php b/src/Symfony/Component/Validator/Constraints/When.php
@@ -25,21 +25,21 @@
 #[\Attribute(\Attribute::TARGET_CLASS | \Attribute::TARGET_PROPERTY | \Attribute::TARGET_METHOD | \Attribute::IS_REPEATABLE)]
 class When extends Composite
 {
-    public string|Expression $expression;
+    public string|Expression|\Closure $expression;
     public array|Constraint $constraints = [];
     public array $values = [];
     public array|Constraint $otherwise = [];
 
     /**
-     * @param string|Expression|array<string,mixed> $expression  The condition to evaluate, written with the ExpressionLanguage syntax
+     * @param string|Expression|array<string,mixed>|\Closure(object): bool $expression The condition to evaluate, either as a closure or using the ExpressionLanguage syntax
      * @param Constraint[]|Constraint|null          $constraints One or multiple constraints that are applied if the expression returns true
      * @param array<string,mixed>|null              $values      The values of the custom variables used in the expression (defaults to [])
      * @param string[]|null                         $groups
      * @param array<string,mixed>|null              $options
      * @param Constraint[]|Constraint               $otherwise   One or multiple constraints that are applied if the expression returns false
      */
     #[HasNamedArguments]
-    public function __construct(string|Expression|array $expression, array|Constraint|null $constraints = null, ?array $values = null, ?array $groups = null, $payload = null, ?array $options = null, array|Constraint $otherwise = [])
+    public function __construct(string|Expression|array|\Closure $expression, array|Constraint|null $constraints = null, ?array $values = null, ?array $groups = null, $payload = null, ?array $options = null, array|Constraint $otherwise = [])
     {
         if (!class_exists(ExpressionLanguage::class)) {
             throw new LogicException(\sprintf('The "symfony/expression-language" component is required to use the "%s" constraint. Try running "composer require symfony/expression-language".', __CLASS__));

diff --git a/src/Symfony/Component/Validator/Constraints/WhenValidator.php b/src/Symfony/Component/Validator/Constraints/WhenValidator.php
@@ -35,7 +35,11 @@ public function validate(mixed $value, Constraint $constraint): void
         $variables['this'] = $context->getObject();
         $variables['context'] = $context;
 
-        $result = $this->getExpressionLanguage()->evaluate($constraint->expression, $variables);
+        if ($constraint->expression instanceof \Closure) {
+            $result = ($constraint->expression)($context->getObject());
+        } else {
+            $result = $this->getExpressionLanguage()->evaluate($constraint->expression, $variables);
+        }
 
         if ($result) {
             $context->getValidator()->inContext($context)

diff --git a/src/Symfony/Component/Validator/Tests/Constraints/Fixtures/WhenTestWithClosure.php b/src/Symfony/Component/Validator/Tests/Constraints/Fixtures/WhenTestWithClosure.php
@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Validator\Tests\Constraints\Fixtures;
+
+use Symfony\Component\Validator\Constraints\NotBlank;
+use Symfony\Component\Validator\Constraints\NotNull;
+use Symfony\Component\Validator\Constraints\When;
+
+#[When(expression: static function () {
+        return true;
+    }, constraints: new NotNull()
+)]
+class WhenTestWithClosure
+{
+    #[When(expression: static function () {
+        return true;
+    }, constraints: [
+        new NotNull(),
+        new NotBlank(),
+    ])]
+    private $foo;
+}
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/WhenTest.php b/src/Symfony/Component/Validator/Tests/Constraints/WhenTest.php
@@ -22,6 +22,7 @@
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 use Symfony\Component\Validator\Mapping\Loader\AttributeLoader;
 use Symfony\Component\Validator\Tests\Constraints\Fixtures\WhenTestWithAttributes;
+use Symfony\Component\Validator\Tests\Constraints\Fixtures\WhenTestWithClosure;
 
 final class WhenTest extends TestCase
 {
@@ -111,4 +112,38 @@ public function testAttributes()
         self::assertEquals([new Length(exactly: 10, groups: ['foo'])], $quuxConstraint->otherwise);
         self::assertSame(['foo'], $quuxConstraint->groups);
     }
+
+    /**
+     * @requires PHP 8.5
+     */
+    public function testAttributesWithClosure()
+    {
+        $loader = new AttributeLoader();
+        $metadata = new ClassMetadata(WhenTestWithClosure::class);
+
+        self::assertTrue($loader->loadClassMetadata($metadata));
+
+        [$classConstraint] = $metadata->getConstraints();
+
+        self::assertInstanceOf(When::class, $classConstraint);
+        self::assertInstanceOf(\Closure::class, $classConstraint->expression);
+        self::assertEquals([
+            new Callback(
+                callback: 'callback',
+                groups: ['Default', 'WhenTestWithClosure'],
+            ),
+        ], $classConstraint->constraints);
+        self::assertEmpty($classConstraint->otherwise);
+
+        [$fooConstraint] = $metadata->properties['foo']->getConstraints();
+
+        self::assertInstanceOf(When::class, $fooConstraint);
+        self::assertInstanceOf(\Closure::class, $fooConstraint->expression);
+        self::assertEquals([
+            new NotNull(groups: ['Default', 'WhenTestWithClosure']),
+            new NotBlank(groups: ['Default', 'WhenTestWithClosure']),
+        ], $fooConstraint->constraints);
+        self::assertEmpty($fooConstraint->otherwise);
+        self::assertSame(['Default', 'WhenTestWithClosure'], $fooConstraint->groups);
+    }
 }
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/WhenValidatorTest.php b/src/Symfony/Component/Validator/Tests/Constraints/WhenValidatorTest.php
@@ -40,6 +40,34 @@ public function testConstraintsAreExecuted()
         ));
     }
 
+    public function testConstraintsAreExecutedWhenClosureIsTrue()
+    {
+        $constraints = [
+            new NotNull(),
+            new NotBlank(),
+        ];
+
+        $this->expectValidateValue(0, 'Foo', $constraints);
+
+        $this->validator->validate('Foo', new When(
+            expression: static fn () => true,
+            constraints: $constraints,
+        ));
+    }
+
+    public function testClosureTakesSubject()
+    {
+        $subject = new \stdClass();
+        $this->setObject($subject);
+
+        $this->validator->validate($subject, new When(
+            expression: static function ($closureSubject) use ($subject) {
+                self::assertSame($subject, $closureSubject);
+            },
+            constraints: new NotNull(),
+        ));
+    }
+
     public function testConstraintIsExecuted()
     {
         $constraint = new NotNull();
@@ -65,6 +93,20 @@ public function testOtherwiseIsExecutedWhenFalse()
         ));
     }
 
+    public function testOtherwiseIsExecutedWhenClosureReturnsFalse()
+    {
+        $constraint = new NotNull();
+        $otherwise = new Length(exactly: 10);
+
+        $this->expectValidateValue(0, 'Foo', [$otherwise]);
+
+        $this->validator->validate('Foo', new When(
+            expression: static fn () => false,
+            constraints: $constraint,
+            otherwise: $otherwise,
+        ));
+    }
+
     public function testConstraintsAreExecutedWithNull()
     {
         $constraints = [