feature #42593 [Validator] Add the When constraint and validator (wuchen90)

This PR was merged into the 6.2 branch.

Discussion
----------

[Validator] Add the `When` constraint and validator

| Q             | A
| ------------- | ---
| Branch?       | 6.2
| Bug fix?      | no
| New feature?  | yes <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#15722

This constraint allows you to apply constraints validation only if the provided condition is matched.

Usage:

```php
namespace App\Model;

use Symfony\Component\Validator\Constraints as Assert;

class Discount
{
    private $type; // 'percent' or 'absolute'

    /**
     * `@Assert`\GreaterThan(0)
     * `@Assert`\When(
     *     expression="this.type == 'percent'",
     *     constraints={`@LessThan`(100, message="The value should be between 0 and 100!")}
     * )
     */
    private $value;
    // ...
}
```

See the documentation for details.

Commits
-------

9b7bdc9 [Validator] Add the When constraint and validator

Author: xabbuh

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

@@ -223,6 +223,7 @@
 use Symfony\Component\Translation\Translator;
 use Symfony\Component\Uid\Factory\UuidFactory;
 use Symfony\Component\Uid\UuidV4;
+use Symfony\Component\Validator\Constraints\WhenValidator;
 use Symfony\Component\Validator\ConstraintValidatorInterface;
 use Symfony\Component\Validator\Mapping\Loader\PropertyInfoLoader;
 use Symfony\Component\Validator\ObjectInitializerInterface;
@@ -1571,6 +1572,10 @@ private function registerValidationConfiguration(array $config, ContainerBuilder
         if (!class_exists(ExpressionLanguage::class)) {
             $container->removeDefinition('validator.expression_language');
         }
+
+        if (!class_exists(WhenValidator::class)) {
+            $container->removeDefinition('validator.when');
+        }
     }
 
     private function registerValidatorMapping(ContainerBuilder $container, array $config, array &$files)

src/Symfony/Bundle/FrameworkBundle/Resources/config/validator.php

@@ -17,6 +17,7 @@
 use Symfony\Component\Validator\Constraints\EmailValidator;
 use Symfony\Component\Validator\Constraints\ExpressionValidator;
 use Symfony\Component\Validator\Constraints\NotCompromisedPasswordValidator;
+use Symfony\Component\Validator\Constraints\WhenValidator;
 use Symfony\Component\Validator\ContainerConstraintValidatorFactory;
 use Symfony\Component\Validator\Mapping\Loader\PropertyInfoLoader;
 use Symfony\Component\Validator\Validation;
@@ -95,6 +96,12 @@
                 'alias' => NotCompromisedPasswordValidator::class,
             ])
 
+        ->set('validator.when', WhenValidator::class)
+            ->args([service('validator.expression_language')->nullOnInvalid()])
+            ->tag('validator.constraint_validator', [
+                'alias' => WhenValidator::class,
+            ])
+
         ->set('validator.property_info_loader', PropertyInfoLoader::class)
             ->args([
                 service('property_info'),

src/Symfony/Component/Validator/CHANGELOG.md

@@ -4,6 +4,7 @@ CHANGELOG
 6.2
 ---
 
+ * Add the `When` constraint and validator
  * Deprecate the "loose" e-mail validation mode, use "html5" instead
  * Add the `negate` option to the `Expression` constraint, to inverse the logic of the violation's creation
 

src/Symfony/Component/Validator/Constraints/When.php

@@ -0,0 +1,69 @@
+<?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\Constraints;
+
+use Symfony\Component\ExpressionLanguage\Expression;
+use Symfony\Component\ExpressionLanguage\ExpressionLanguage;
+use Symfony\Component\Validator\Exception\LogicException;
+
+/**
+ * @Annotation
+ * @Target({"CLASS", "PROPERTY", "METHOD", "ANNOTATION"})
+ */
+#[\Attribute(\Attribute::TARGET_CLASS | \Attribute::TARGET_PROPERTY | \Attribute::TARGET_METHOD | \Attribute::IS_REPEATABLE)]
+class When extends Composite
+{
+    public $expression;
+    public $constraints = [];
+    public $values = [];
+
+    public function __construct(string|Expression|array $expression, array $constraints = null, array $values = null, array $groups = null, $payload = null, array $options = [])
+    {
+        if (!class_exists(ExpressionLanguage::class)) {
+            throw new LogicException(sprintf('The "symfony/expression-language" component is required to use the "%s" constraint. Try running "composer require symfony/expression-language".', __CLASS__));
+        }
+
+        if (\is_array($expression)) {
+            $options = array_merge($expression, $options);
+        } else {
+            $options['expression'] = $expression;
+            $options['constraints'] = $constraints;
+        }
+
+        if (null !== $groups) {
+            $options['groups'] = $groups;
+        }
+
+        if (null !== $payload) {
+            $options['payload'] = $payload;
+        }
+
+        parent::__construct($options);
+
+        $this->values = $values ?? $this->values;
+    }
+
+    public function getRequiredOptions(): array
+    {
+        return ['expression', 'constraints'];
+    }
+
+    public function getTargets(): string|array
+    {
+        return [self::CLASS_CONSTRAINT, self::PROPERTY_CONSTRAINT];
+    }
+
+    protected function getCompositeOption(): string
+    {
+        return 'constraints';
+    }
+}

src/Symfony/Component/Validator/Constraints/WhenValidator.php

@@ -0,0 +1,61 @@
+<?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\Constraints;
+
+use Symfony\Component\ExpressionLanguage\ExpressionLanguage;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\LogicException;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+
+final class WhenValidator extends ConstraintValidator
+{
+    private ?ExpressionLanguage $expressionLanguage;
+
+    public function __construct(ExpressionLanguage $expressionLanguage = null)
+    {
+        $this->expressionLanguage = $expressionLanguage;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function validate(mixed $value, Constraint $constraint): void
+    {
+        if (!$constraint instanceof When) {
+            throw new UnexpectedTypeException($constraint, When::class);
+        }
+
+        $context = $this->context;
+        $variables = $constraint->values;
+        $variables['value'] = $value;
+        $variables['this'] = $context->getObject();
+
+        if ($this->getExpressionLanguage()->evaluate($constraint->expression, $variables)) {
+            $context->getValidator()->inContext($context)
+                ->validate($value, $constraint->constraints);
+        }
+    }
+
+    private function getExpressionLanguage(): ExpressionLanguage
+    {
+        if (null !== $this->expressionLanguage) {
+            return $this->expressionLanguage;
+        }
+
+        if (!class_exists(ExpressionLanguage::class)) {
+            throw new LogicException(sprintf('The "symfony/expression-language" component is required to use the "%s" validator. Try running "composer require symfony/expression-language".', __CLASS__));
+        }
+
+        return $this->expressionLanguage = new ExpressionLanguage();
+    }
+}

src/Symfony/Component/Validator/Tests/Constraints/Fixtures/WhenTestWithAttributes.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace Symfony\Component\Validator\Tests\Constraints\Fixtures;
+
+use Symfony\Component\Validator\Constraints\Callback;
+use Symfony\Component\Validator\Constraints\NotBlank;
+use Symfony\Component\Validator\Constraints\NotNull;
+use Symfony\Component\Validator\Constraints\When;
+
+#[When(expression: 'true', constraints: [
+    new Callback('callback'),
+])]
+class WhenTestWithAttributes
+{
+    #[When(expression: 'true', constraints: [
+        new NotNull(),
+        new NotBlank(),
+    ])]
+    private $foo;
+
+    #[When(expression: 'false', constraints: [
+        new NotNull(),
+        new NotBlank(),
+    ], groups: ['foo'])]
+    private $bar;
+
+    #[When(expression: 'true', constraints: [
+        new NotNull(),
+        new NotBlank(),
+    ])]
+    public function getBaz()
+    {
+        return null;
+    }
+
+    public function callback()
+    {
+    }
+}