如何将具有嵌套属性的 JSON 对象反序列化为 Symfony 实体？

Question

我正在将 JSON 反序列化为一个 php 类（一个 Symfony 实体），它工作正常，但我的 JSON 中有一个嵌套属性，我不知道如何进入 php 类。

PHP 类：

class Vehicle
{
    private $make:

    /**
     * @SerializedName("meta")
     */
    private $colour;

    // with getters and setters...
}

// These 2 lines let us use the @SerializedName annotation
$metadataAwareNameConverter = new MetadataAwareNameConverter($classMetadataFactory);
$objectNormalizer = new ObjectNormalizer($classMetadataFactory, $metadataAwareNameConverter);

$encoders = [new JsonEncoder()];
$normalizers = [$objectNormalizer];
$serializer = new Serializer($normalizers, $encoders);

$json = '
    {
        "make": "VW Golf",
        "meta": {
            "colour": "red"
        }
    }
';
$carJson = json_encode($json);

$vehicle = $serializer->deserialize(
    $carJson,
    Vehicle::class,
    'json',
);

$vehicle->getMake(); // VW Golf
$vehicle->getColour(); // ['meta' => ['colour' => 'red']]

...但最后一行应该只返回red。

我希望我可以做类似@SerializedName("meta.colour") 或@SerializedName("[meta][colour]") 或@SerializedName("meta[colour]") 之类的事情，但这些都决定为空。

Symfony docs on serialization 看起来无法处理这种（简单）案例。

This Stackoverflow post 也处理嵌套属性，但在他们的示例中，嵌套属性必须反序列化到另一个 php 类，而不是映射到现有的 php 类，所以这对我没有帮助。

在反序列化 JSON 时，如何使 $colour 等于 red？

Answer 1

自定义规范器可以解决问题。代码如下。

<?php

namespace App\Serializer\Denormalizer;

use App\Entity\Vehicle;
use Symfony\Component\PropertyAccess\PropertyAccess;
use Symfony\Component\PropertyAccess\PropertyAccessor;
use Symfony\Component\Serializer\Normalizer\CacheableSupportsMethodInterface;
use Symfony\Component\Serializer\Normalizer\ContextAwareDenormalizerInterface;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;

class VehicleDenormalizer implements CacheableSupportsMethodInterface, ContextAwareDenormalizerInterface
{
    protected ObjectNormalizer $normalizer;
    protected PropertyAccessor $propertyAccessor;

    public function __construct(ObjectNormalizer $normalizer)
    {
        $this->normalizer = $normalizer;
        $this->propertyAccessor = PropertyAccess::createPropertyAccessor();
    }

    public function denormalize($data, $type, $format = null, array $context = []): Vehicle
    {
        /** @var Vehicle */
        $vehicle = $this->normalizer->denormalize($data, $type, $format, $context);

        // It's possible to directly access the values, but that requires error
        // checking. This method will return a null if it doesn't exist.
        $colour = $this->propertyAccessor->getValue($data, '[meta][colour]');
        $vehicle->setColour($colour);

        return $vehicle;
    }

    public function supportsDenormalization($data, $type, $format = null, array $context = [])
    {
        return Vehicle::class == $type;
    }

    public function hasCacheableSupportsMethod(): bool
    {
        return true;
    }
}

要使用此反规范化器，您可以注入 SerializerInterface 或显式创建序列化器（代码如下）。

$json = '
    {
        "make": "VW Golf",
        "meta": {
            "colour": "red"
        }
    }
';
$carJson = json_encode($json);

// These 2 lines let us use the @SerializedName annotation
$metadataAwareNameConverter = new MetadataAwareNameConverter($classMetadataFactory);
$objectNormalizer = new ObjectNormalizer($classMetadataFactory, $metadataAwareNameConverter);

$normalizers = [new VehicleDenormalizer($objectNormalizer)];
$serializer = new Serializer($normalizers);

/** @var Vehicle */
$vehicle = $serializer->denormalize(
    $carJson,
    Vehicle::class,
);

$vehicle->getMake(); // VW Golf
$vehicle->getColour(); // red

我正在显式创建序列化程序，因为由于某种原因，当源数据是字符串而目标数据是整数时，注入方法 not 不会自动转换类型，我得到以下错误：

The type of the "VehicleNo" attribute for class "App\Entity\Vehicle" must be one of "int" ("string" given).

（这个代码示例没有使用VehicleNo，因为我已经对其进行了简化，而是将其包含在此处以显示错误消息的示例，其中Vehicle 具有$vehicleNo 类型的@987654328 属性@)。