Symfony反序列化时如何校验对象属性初始化并抛出异常

现有如下DTO类：

class SimpleDto implements GetPhoneInterface
{
    public string $name;

    public int $value;
}

对应JSON数据：

{"name":"Jane"}

执行反序列化操作：

$serializer = self::getContainer()->get(SerializerInterface::class);
$dto = $serializer->deserialize($json, $dtoClass);

得到的$dto中$value处于未初始化状态，需要实现：反序列化时若存在未初始化属性则抛出异常；同时询问是否可通过Validator组件实现校验。

另外尝试继承ObjectNormalizer实现，但该类为final无法继承，需更优方案。

方案一：通过序列化组件的服务装饰器实现 #

由于ObjectNormalizer是final类无法继承，可采用服务装饰器模式包装原有逻辑，在反序列化完成后添加未初始化属性校验：

1. 编写装饰器类 #

use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
use Symfony\Component\Serializer\Exception\NotNormalizableValueException;

class InitializedPropertiesValidatorNormalizer implements DenormalizerInterface, NormalizerInterface
{
    private DenormalizerInterface&NormalizerInterface $decorated;

    public function __construct(DenormalizerInterface&NormalizerInterface $decorated)
    {
        $this->decorated = $decorated;
    }

    public function denormalize(mixed $data, string $type, ?string $format = null, array $context = [])
    {
        // 先执行原有反序列化逻辑
        $object = $this->decorated->denormalize($data, $type, $format, $context);

        // 校验所有属性是否初始化
        $reflection = new \ReflectionObject($object);
        $errors = [];

        foreach ($reflection->getProperties() as $property) {
            if (!$property->isInitialized($object)) {
                $errors[] = sprintf('属性 "%s" 未初始化', $property->getName());
            }
        }

        if (!empty($errors)) {
            throw new NotNormalizableValueException(implode('; ', $errors));
        }

        return $object;
    }

    public function supportsDenormalization(mixed $data, string $type, ?string $format = null, array $context = []): bool
    {
        return $this->decorated->supportsDenormalization($data, $type, $format, $context);
    }

    // 序列化相关方法直接委托给被装饰的normalizer
    public function normalize(mixed $object, ?string $format = null, array $context = [])
    {
        return $this->decorated->normalize($object, $format, $context);
    }

    public function supportsNormalization(mixed $data, ?string $format = null, array $context = []): bool
    {
        return $this->decorated->supportsNormalization($data, $format, $context);
    }

    public function getSupportedTypes(?string $format): array
    {
        return $this->decorated->getSupportedTypes($format);
    }
}

2. 配置服务装饰器 #

在services.yaml中注册装饰器，替换原有ObjectNormalizer的调用链：

services:
    App\Serializer\InitializedPropertiesValidatorNormalizer:
        decorates: Symfony\Component\Serializer\Normalizer\ObjectNormalizer
        arguments: ['@.inner']

配置完成后，所有反序列化操作都会自动触发未初始化属性校验，存在问题时直接抛出异常。

方案二：使用Validator组件自定义约束校验 #

若希望更灵活地控制校验规则（比如区分必填/可选属性），可通过Validator组件实现：

1. 自定义Initialized约束 #

use Symfony\Component\Validator\Constraint;

#[\Attribute]
class Initialized extends Constraint
{
    public string $message = '属性 "{{ property }}" 未初始化';

    public function getTargets(): string
    {
        return self::PROPERTY_CONSTRAINT;
    }
}

2. 编写约束验证器 #

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

class InitializedValidator extends ConstraintValidator
{
    public function validate(mixed $value, Constraint $constraint): void
    {
        if (!$constraint instanceof Initialized) {
            return;
        }

        $property = $this->context->getProperty();
        $object = $this->context->getObject();

        if (!$property || !$object) {
            return;
        }

        $reflectionProperty = new \ReflectionProperty($object::class, $property->getName());
        if (!$reflectionProperty->isInitialized($object)) {
            $this->context->buildViolation($constraint->message)
                ->setParameter('{{ property }}', $property->getName())
                ->addViolation();
        }
    }
}

3. 给DTO属性添加约束 #

use App\Validator\Constraints as AppAssert;

class SimpleDto implements GetPhoneInterface
{
    #[AppAssert\Initialized]
    public string $name;

    #[AppAssert\Initialized]
    public int $value;
}

4. 反序列化后执行校验 #

$serializer = self::getContainer()->get(SerializerInterface::class);
$validator = self::getContainer()->get(ValidatorInterface::class);

$dto = $serializer->deserialize($json, $dtoClass);
$violations = $validator->validate($dto);

if (count($violations) > 0) {
    // 处理校验错误，示例：抛出异常
    throw new \RuntimeException((string) $violations);
}

方案对比 #

• 装饰器方案：无需手动触发校验，逻辑嵌入序列化流程，适合全局强制校验场景。
• Validator方案：可针对单个属性配置规则，灵活性更高，适合需要区分必填/可选属性的场景。

内容的提问来源于stack exchange，提问作者sveta600