feature #51348 [FrameworkBundle][Validator] Allow implementing validation groups provider outside DTOs (Yonel Ceruto)

This PR was squashed before being merged into the 6.4 branch.

Discussion
----------

[FrameworkBundle][Validator] Allow implementing validation groups provider outside DTOs

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | symfony/symfony-docs#18744

Alternative to symfony/symfony#51233
Inspiration: symfony/symfony#51012

Currently, you can determine the sequence of groups to apply dynamically based on the state of your DTO by implementing the `GroupSequenceProviderInterface` in your DTO class. https://symfony.com/doc/current/validation/sequence_provider.html#group-sequence-providers
```php
use Symfony\Component\Validator\GroupSequenceProviderInterface;

#[Assert\GroupSequenceProvider]
class UserDto implements GroupSequenceProviderInterface
{
    // ...

    public function getGroupSequence(): array|GroupSequence
    {
        if ($this->isCompanyType()) {
            return ['User', 'Company'];
        }

        return ['User'];
    }
}
```
It covers most of the common scenarios, but for more advanced ones, it may not be sufficient. Suppose now you need to provide the sequence of groups from an external configuration (or service) which can change its value dynamically:
```php
#[Assert\GroupSequenceProvider]
class UserDto implements GroupSequenceProviderInterface
{
    // ...

    public __constructor(private readonly ConfigService $config)
    {
    }

    public function getGroupSequence(): array|GroupSequence
    {
        if ($this->config->isEnabled()) {
            return ['User', $this->config->getGroup()];
        }

        return ['User'];
    }
}
```
This issue cannot be resolved at present without managing the DTO initialization and manually setting its dependencies. On the other hand, since the state of the DTO is not used at all, the implementation of the `GroupSequenceProviderInterface` becomes less fitting to the DTO responsibility. Further, stricter programming may raise a complaint about a violation of SOLID principles here.

So, the proposal of this PR is to allow configuring the validation groups provider outside of the DTO, while simultaneously enabling the registration of this provider as a service if necessary.

To achieve this, you'll need to implement a new `GroupProviderInterface` in a separate class, and configure it using the new `provider` option within the `GroupSequenceProvider` attribute:
```php
#[Assert\GroupSequenceProvider(provider: UserGroupProvider::class)]
class UserDto
{
    // ...
}

class UserGroupProvider implements GroupProviderInterface
{
    public __constructor(private readonly ConfigService $config)
    {
    }

    public function getGroups(object $object): array|GroupSequence
    {
        if ($this->config->isEnabled()) {
            return ['User', $this->config->getGroup()];
        }

        return ['User'];
    }
}
```
That's all you'll need to do if autowiring is enabled under your custom provider. Otherwise, you can manually tag your service with `validator.group_provider` to collect it and utilize it as a provider service during the validation process.

In conclusion, no more messing with the DTO structure, just use the new `class` option for more advanced use cases.

---

TODO:

- [x] Add tests
- [x] Create doc PR

Commits
-------

a3a089a15b8 [FrameworkBundle][Validator] Allow implementing validation groups provider outside DTOs

Author: fabpot

CHANGELOG.md

@@ -15,6 +15,7 @@ CHANGELOG
  * Deprecate `ValidatorBuilder::enableAnnotationMapping()`, use `ValidatorBuilder::enableAttributeMapping()` instead
  * Deprecate `ValidatorBuilder::disableAnnotationMapping()`, use `ValidatorBuilder::disableAttributeMapping()` instead
  * Deprecate `AnnotationLoader`, use `AttributeLoader` instead
+ * Add `GroupProviderInterface` to implement validation group providers outside the underlying class
 
 6.3
 ---

Constraints/GroupSequenceProvider.php

@@ -11,16 +11,25 @@
 
 namespace Symfony\Component\Validator\Constraints;
 
+use Doctrine\Common\Annotations\Annotation\NamedArgumentConstructor;
+use Symfony\Component\Validator\Attribute\HasNamedArguments;
+
 /**
  * Attribute to define a group sequence provider.
  *
  * @Annotation
  *
+ * @NamedArgumentConstructor
+ *
  * @Target({"CLASS", "ANNOTATION"})
  *
  * @author Bernhard Schussek <bschussek@gmail.com>
  */
 #[\Attribute(\Attribute::TARGET_CLASS)]
 class GroupSequenceProvider
 {
+    #[HasNamedArguments]
+    public function __construct(public ?string $provider = null)
+    {
+    }
 }

GroupProviderInterface.php

@@ -0,0 +1,30 @@
+<?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;
+
+use Symfony\Component\Validator\Constraints\GroupSequence;
+
+/**
+ * Defines the interface for a validation group provider.
+ *
+ * @author Yonel Ceruto <yonelceruto@gmail.com>
+ */
+interface GroupProviderInterface
+{
+    /**
+     * Returns which validation groups should be used for a certain state
+     * of the object.
+     *
+     * @return string[]|string[][]|GroupSequence
+     */
+    public function getGroups(object $object): array|GroupSequence;
+}

Mapping/ClassMetadata.php

@@ -86,6 +86,13 @@ class ClassMetadata extends GenericMetadata implements ClassMetadataInterface
      */
     public bool $groupSequenceProvider = false;
 
+    /**
+     * @internal This property is public in order to reduce the size of the
+     *           class' serialized representation. Do not access it. Use
+     *           {@link getGroupProvider()} instead.
+     */
+    public ?string $groupProvider = null;
+
     /**
      * The strategy for traversing traversable objects.
      *
@@ -123,6 +130,7 @@ public function __sleep(): array
             'getters',
             'groupSequence',
             'groupSequenceProvider',
+            'groupProvider',
             'members',
             'name',
             'properties',
@@ -319,6 +327,7 @@ public function addGetterMethodConstraints(string $property, string $method, arr
     public function mergeConstraints(self $source)
     {
         if ($source->isGroupSequenceProvider()) {
+            $this->setGroupProvider($source->getGroupProvider());
             $this->setGroupSequenceProvider(true);
         }
 
@@ -432,7 +441,7 @@ public function setGroupSequenceProvider(bool $active)
             throw new GroupDefinitionException('Defining a group sequence provider is not allowed with a static group sequence.');
         }
 
-        if (!$this->getReflectionClass()->implementsInterface(GroupSequenceProviderInterface::class)) {
+        if (null === $this->groupProvider && !$this->getReflectionClass()->implementsInterface(GroupSequenceProviderInterface::class)) {
             throw new GroupDefinitionException(sprintf('Class "%s" must implement GroupSequenceProviderInterface.', $this->name));
         }
 
@@ -444,6 +453,16 @@ public function isGroupSequenceProvider(): bool
         return $this->groupSequenceProvider;
     }
 
+    public function setGroupProvider(?string $provider): void
+    {
+        $this->groupProvider = $provider;
+    }
+
+    public function getGroupProvider(): ?string
+    {
+        return $this->groupProvider;
+    }
+
     public function getCascadingStrategy(): int
     {
         return $this->cascadingStrategy;

Mapping/ClassMetadataInterface.php

@@ -30,6 +30,8 @@
  * @see GroupSequence
  * @see GroupSequenceProviderInterface
  * @see TraversalStrategy
+ *
+ * @method string|null getGroupProvider()
  */
 interface ClassMetadataInterface extends MetadataInterface
 {

Mapping/Loader/AnnotationLoader.php

@@ -51,6 +51,7 @@ public function loadClassMetadata(ClassMetadata $metadata): bool
             if ($constraint instanceof GroupSequence) {
                 $metadata->setGroupSequence($constraint->groups);
             } elseif ($constraint instanceof GroupSequenceProvider) {
+                $metadata->setGroupProvider($constraint->provider);
                 $metadata->setGroupSequenceProvider(true);
             } elseif ($constraint instanceof Constraint) {
                 $metadata->addConstraint($constraint);

Mapping/Loader/XmlFileLoader.php

@@ -201,6 +201,7 @@ private function loadClassesFromXml(): void
     private function loadClassMetadataFromXml(ClassMetadata $metadata, \SimpleXMLElement $classDescription): void
     {
         if (\count($classDescription->{'group-sequence-provider'}) > 0) {
+            $metadata->setGroupProvider($classDescription->{'group-sequence-provider'}[0]->value ?: null);
             $metadata->setGroupSequenceProvider(true);
         }
 

Mapping/Loader/YamlFileLoader.php

@@ -150,6 +150,9 @@ private function loadClassesFromYaml(): void
     private function loadClassMetadataFromYaml(ClassMetadata $metadata, array $classDescription): void
     {
         if (isset($classDescription['group_sequence_provider'])) {
+            if (\is_string($classDescription['group_sequence_provider'])) {
+                $metadata->setGroupProvider($classDescription['group_sequence_provider']);
+            }
             $metadata->setGroupSequenceProvider(
                 (bool) $classDescription['group_sequence_provider']
             );

Mapping/Loader/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd

@@ -14,9 +14,9 @@
       validation constraints.
     ]]></xsd:documentation>
   </xsd:annotation>
-  
+
   <xsd:element name="constraint-mapping" type="constraint-mapping" />
-  
+
   <xsd:complexType name="constraint-mapping">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
@@ -28,7 +28,7 @@
       <xsd:element name="class" type="class" maxOccurs="unbounded" />
     </xsd:sequence>
   </xsd:complexType>
-  
+
   <xsd:complexType name="namespace">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
@@ -41,13 +41,13 @@
       </xsd:extension>
     </xsd:simpleContent>
   </xsd:complexType>
-  
+
   <xsd:complexType name="class">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
         Contains constraints for a single class.
-        
-        Nested elements may be class constraints, property and/or getter 
+
+        Nested elements may be class constraints, property and/or getter
         definitions.
       ]]></xsd:documentation>
     </xsd:annotation>
@@ -72,15 +72,18 @@
       <xsd:element name="value" type="value" minOccurs="1" maxOccurs="unbounded" />
     </xsd:sequence>
   </xsd:complexType>
-  
+
   <xsd:complexType name="group-sequence-provider">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
         Defines the name of the group sequence provider for a class.
       ]]></xsd:documentation>
     </xsd:annotation>
+    <xsd:sequence>
+      <xsd:element name="value" type="value" minOccurs="0" maxOccurs="unbounded" />
+    </xsd:sequence>
   </xsd:complexType>
-  
+
   <xsd:complexType name="property">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
@@ -93,7 +96,7 @@
     </xsd:sequence>
     <xsd:attribute name="name" type="xsd:string" use="required" />
   </xsd:complexType>
-  
+
   <xsd:complexType name="getter">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
@@ -106,14 +109,14 @@
     </xsd:sequence>
     <xsd:attribute name="property" type="xsd:string" use="required" />
   </xsd:complexType>
-  
+
   <xsd:complexType name="constraint" mixed="true">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
         Contains a constraint definition. The name of the constraint should be
         given in the "name" option.
-        
-        May contain a single value, multiple "constraint" elements, 
+
+        May contain a single value, multiple "constraint" elements,
         multiple "value" elements or multiple "option" elements.
       ]]></xsd:documentation>
     </xsd:annotation>
@@ -122,15 +125,15 @@
       <xsd:element name="option" type="option" minOccurs="1" maxOccurs="unbounded" />
       <xsd:element name="value" type="value" minOccurs="1" maxOccurs="unbounded" />
     </xsd:choice>
-    <xsd:attribute name="name" type="xsd:string" use="required" />    
+    <xsd:attribute name="name" type="xsd:string" use="required" />
   </xsd:complexType>
-  
+
   <xsd:complexType name="option" mixed="true">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
         Contains a constraint option definition. The name of the option
         should be given in the "name" option.
-        
+
         May contain a single value, multiple "value" elements or multiple
         "constraint" elements.
       ]]></xsd:documentation>
@@ -139,14 +142,14 @@
       <xsd:element name="constraint" type="constraint" minOccurs="1" maxOccurs="unbounded" />
       <xsd:element name="value" type="value" minOccurs="1" maxOccurs="unbounded" />
     </xsd:choice>
-    <xsd:attribute name="name" type="xsd:string" use="required" />  
+    <xsd:attribute name="name" type="xsd:string" use="required" />
   </xsd:complexType>
-  
+
   <xsd:complexType name="value" mixed="true">
     <xsd:annotation>
       <xsd:documentation><![CDATA[
         A value of an element.
-        
+
         May contain a single value, multiple "value" elements or multiple
         "constraint" elements.
       ]]></xsd:documentation>
@@ -155,6 +158,6 @@
       <xsd:element name="constraint" type="constraint" minOccurs="1" maxOccurs="unbounded" />
       <xsd:element name="value" type="value" minOccurs="1" maxOccurs="unbounded" />
     </xsd:choice>
-    <xsd:attribute name="key" type="xsd:string" use="optional" /> 
+    <xsd:attribute name="key" type="xsd:string" use="optional" />
   </xsd:complexType>
 </xsd:schema>

Tests/Constraints/GroupSequenceProviderTest.php

@@ -0,0 +1,26 @@
+<?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;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Validator\Constraints\GroupSequenceProvider;
+use Symfony\Component\Validator\Tests\Dummy\DummyGroupProvider;
+
+class GroupSequenceProviderTest extends TestCase
+{
+    public function testCreateAttributeStyle()
+    {
+        $sequence = new GroupSequenceProvider(provider: DummyGroupProvider::class);
+
+        $this->assertSame(DummyGroupProvider::class, $sequence->provider);
+    }
+}

Tests/Dummy/DummyGroupProvider.php

@@ -0,0 +1,23 @@
+<?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\Dummy;
+
+use Symfony\Component\Validator\Constraints\GroupSequence;
+use Symfony\Component\Validator\GroupProviderInterface;
+
+class DummyGroupProvider implements GroupProviderInterface
+{
+    public function getGroups(object $object): array|GroupSequence
+    {
+        return ['foo', 'bar'];
+    }
+}

Tests/Fixtures/Attribute/GroupProviderDto.php

@@ -0,0 +1,22 @@
+<?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\Fixtures\Attribute;
+
+use Symfony\Component\Validator\Constraints as Assert;
+use Symfony\Component\Validator\Tests\Dummy\DummyGroupProvider;
+
+#[Assert\GroupSequenceProvider(provider: DummyGroupProvider::class)]
+class GroupProviderDto
+{
+    public string $firstName = '';
+    public string $lastName = '';
+}

Tests/Mapping/Loader/XmlFileLoaderTest.php

@@ -24,6 +24,8 @@
 use Symfony\Component\Validator\Exception\MappingException;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 use Symfony\Component\Validator\Mapping\Loader\XmlFileLoader;
+use Symfony\Component\Validator\Tests\Dummy\DummyGroupProvider;
+use Symfony\Component\Validator\Tests\Fixtures\Attribute\GroupProviderDto;
 use Symfony\Component\Validator\Tests\Fixtures\ConstraintA;
 use Symfony\Component\Validator\Tests\Fixtures\ConstraintB;
 use Symfony\Component\Validator\Tests\Fixtures\ConstraintWithRequiredArgument;
@@ -126,6 +128,20 @@ public function testLoadGroupSequenceProvider()
         $this->assertEquals($expected, $metadata);
     }
 
+    public function testLoadGroupProvider()
+    {
+        $loader = new XmlFileLoader(__DIR__.'/constraint-mapping.xml');
+        $metadata = new ClassMetadata(GroupProviderDto::class);
+
+        $loader->loadClassMetadata($metadata);
+
+        $expected = new ClassMetadata(GroupProviderDto::class);
+        $expected->setGroupProvider(DummyGroupProvider::class);
+        $expected->setGroupSequenceProvider(true);
+
+        $this->assertEquals($expected, $metadata);
+    }
+
     public function testThrowExceptionIfDocTypeIsSet()
     {
         $loader = new XmlFileLoader(__DIR__.'/withdoctype.xml');