error-handling - 如果已经存在，则返回实体-API平台

Question

我有实体Tag，它具有唯一的属性tagValue。当我用已经存在的POST制作tagValue时，我想获得它作为响应。
config/validator/tag.yaml:

App\Entity\Tag:
  constraints:
    - Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity: tagValue
  properties:
    tagValue:
      - NotBlank: ~

src/Entity/Tag.php:

<?php

namespace App\Entity;

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;
use DateTimeInterface;
use DateTime;
use Exception;

/**
 * @ORM\Table(name="tag")
 * @ORM\Entity(repositoryClass="App\Repository\TagRepository")
 * @ORM\HasLifecycleCallbacks
 */
class Tag
{
    /**
     * @var int
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @var string
     * @ORM\Column(type="string", length=255)
     */
    private $tagValue;

    // ...
}

当我制作 POST时:

curl --request POST \
  --url http://127.0.0.1:8888/api/tags \
  --header 'accept: application/json' \
  --header 'content-type: application/json' \
  --header 'x-auth-token: xxxxxxxxxxxxxxxx' \
  --data '{
    "tagValue": "test"
}'

我得到了刚创建的实体和代码201的响应。一切正常，但是，如果我如预期的那样再次发出此请求，我将获得带有响应主体的响应代码400:

{
  "type": "https:\/\/tools.ietf.org\/html\/rfc2616#section-10",
  "title": "An error occurred",
  "detail": "tagValue: This value is already used.",
  "violations": [
    {
      "propertyPath": "tagValue",
      "message": "This value is already used."
    }
  ]
}

但是我希望存在实体对此做出回应。

有什么想法如何做到这一点而不破坏REST规则？

(Symfony 4.2.5，api-platform/api-pack 1.2.0)

Answer 1

最终，我从maks-rafalko在GitHub上得到了一个答案(对此我非常感激)，如果有人坚持同样的问题，这里是his solution:

You are lucky man, we have just implemented it inside our application. There is no built in functionality in API-Platform for this feature, we had to override some classes in order to add it.

首先，这是当唯一性约束无效时我们的响应现在的样子:

{
  "type": "https://tools.ietf.org/html/rfc2616#section-10",
  "title": "An error occurred",
  "detail": "number: This Usage Reference already exists with the same number and channel.",
  "violations": [
    {
      "propertyPath": "number",
      "message": "This Usage Reference already exists with the same number and channel."
    }
  ],
  "existingUniqueEntities": [
    {
      "uniquePropertyPaths": [
        "number",
        "channel"
      ],
      "entity": {
        "id": 1101,
        "number": "23423423435",
        "channel": "/api/channels/1",
        "createdAt": "2019-07-17T07:25:50.721Z"
      }
    }
  ]
}

请注意，您可能有很多独特的违规行为，这种模式可以返回许多已经存在并与提供的请求冲突的实体(例如，实体可以具有两对唯一键，一对通过电子邮件，另一对通过引用) )

此外，我们的实现完全使用执行GET/resource时将使用的序列化组，其中resource是您要创建的资源。我们从api平台元数据中获得那些序列化组

所以这是代码:

<?php

declare(strict_types=1);

namespace App\Serializer;

use ApiPlatform\Core\Metadata\Resource\Factory\ResourceMetadataFactoryInterface;
use ApiPlatform\Core\Serializer\AbstractConstraintViolationListNormalizer;
use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;
use Symfony\Component\Serializer\NameConverter\NameConverterInterface;
use Symfony\Component\Serializer\Normalizer\NormalizerAwareInterface;
use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
use Symfony\Component\Serializer\SerializerInterface;
use Symfony\Component\Validator\ConstraintViolation;
use Symfony\Component\Validator\ConstraintViolationListInterface;

/**
 * This class completely overrides `ApiPlatform\Core\Problem\Serializer\ConstraintViolationListNormalizer` class
 * since it's final
 *
 * Goal of overriding is to add `existingUniqueEntities` key when ViolationList contains unique entity violations
 *
 * @see \ApiPlatform\Core\Problem\Serializer\ConstraintViolationListNormalizer
 */
class ConstraintViolationListNormalizer extends AbstractConstraintViolationListNormalizer implements NormalizerAwareInterface
{
    public const FORMAT = 'jsonproblem';
    public const TYPE = 'type';
    public const TITLE = 'title';

    /**
     * @var array<string, string>
     */
    private $defaultContext = [
        self::TYPE => 'https://tools.ietf.org/html/rfc2616#section-10',
        self::TITLE => 'An error occurred',
    ];

    /**
     * @var ResourceMetadataFactoryInterface
     */
    private $resourceMetadataFactory;

    /**
     * @var SerializerInterface
     */
    private $serializer;

    /**
     * @var NormalizerInterface
     */
    private $normalizer;

    public function __construct(ResourceMetadataFactoryInterface $resourceMetadataFactory, array $serializePayloadFields = null, NameConverterInterface $nameConverter = null, array $defaultContext = [])
    {
        parent::__construct($serializePayloadFields, $nameConverter);

        $this->resourceMetadataFactory = $resourceMetadataFactory;
        $this->defaultContext = array_merge($this->defaultContext, $defaultContext);
    }

    public function setNormalizer(NormalizerInterface $normalizer): void
    {
        $this->normalizer = $normalizer;
    }

    /**
     * @param mixed $object
     * @param string|null $format
     * @param array $context
     *
     * @return array
     */
    public function normalize($object, $format = null, array $context = []): array
    {
        [$messages, $violations] = $this->getMessagesAndViolations($object);

        $response = [
            'type' => $context[self::TYPE] ?? $this->defaultContext[self::TYPE],
            'title' => $context[self::TITLE] ?? $this->defaultContext[self::TITLE],
            'detail' => $messages ? implode("\n", $messages) : (string) $object,
            'violations' => $violations,
        ];

        $existingUniqueEntities = $this->getExistingUniqueEntities($object);

        return \count($existingUniqueEntities) > 0 ?
            array_merge($response, ['existingUniqueEntities' => $existingUniqueEntities])
            : $response;
    }

    private function getExistingUniqueEntities(ConstraintViolationListInterface $constraintViolationList): array
    {
        $existingUniqueEntities = [];

        /** @var ConstraintViolation $violation */
        foreach ($constraintViolationList as $violation) {
            $constraint = $violation->getConstraint();

            if (!$constraint instanceof UniqueEntity) {
                continue;
            }

            $rootEntity = \is_object($violation->getRoot()) ? $violation->getRoot() : null;

            if ($rootEntity === null) {
                continue;
            }

            $existingEntityCausedViolation = $violation->getCause()[0];

            $metadata = $this->resourceMetadataFactory->create(\get_class($existingEntityCausedViolation));

            // get normalization groups for `GET /resource` operation, fallback to global resource groups
            $normalizationContext = $metadata->getItemOperationAttribute('get', 'normalization_context', [], true);
            $groups = $normalizationContext['groups'] ?? [];
            $entityNormalizationContext = \count($groups) > 0 ? ['groups' => $groups] : [];

            $existingUniqueEntities[] = [
                'uniquePropertyPaths' => $constraint->fields,
                'entity' => $this->normalizer->normalize($existingEntityCausedViolation, null, $entityNormalizationContext),
            ];
        }

        return $existingUniqueEntities;
    }
}

一切都在getExistingUniqueEntities内部，但是不幸的是，我们不得不完全重写ApiPlatform \ Core \ Problem \ Serializer \ ConstraintViolationListNormalizer类，因为它是最终的，无法扩展。

我们设法使用Compiler Pass覆盖了它:

# src/Kernel.php

class Kernel extends BaseKernel implements CompilerPassInterface
{

private const CONSTRAINT_VIOLATION_LIST_NORMALIZER_PRIORITY = -780;

...

public function process(ContainerBuilder $container)
{
    ...
    $constraintViolationListNormalizerDefinition = new Definition(
        ConstraintViolationListNormalizer::class,
        [
            $container->getDefinition('api_platform.metadata.resource.metadata_factory.cached'),
            $container->getParameter('api_platform.validator.serialize_payload_fields'),
            $container->hasDefinition('api_platform.name_converter') ? $container->getDefinition('api_platform.name_converter') : null,
            [],
        ]
    );
    $constraintViolationListNormalizerDefinition->addTag('serializer.normalizer', ['priority' => self::CONSTRAINT_VIOLATION_LIST_NORMALIZER_PRIORITY]);

    $container->setDefinition('api_platform.problem.normalizer.constraint_violation_list', $constraintViolationListNormalizerDefinition);
}

So, this solution is based on Symfony Validator and "listens" UniqueEntity vailoations. And if there are such violations, this normalizer adds already existing entity(ies) to the response.

Hope it helps!