如何使SymfonySerializer的屬性可以為空

我正在嘗試反序列化為具有屬性的物件，該物件可能將一組物件作為值或為null.

我反序列化陣列沒有問題，但我需要將 null 反序列化為空陣列或 null 本身。

例如 { "items": null }

class A {
    /**
     * @var null|Item[]
     */
    private $items = [];

    /**
     * @return Item[]|null
     */
    public function getItems(): ?array
    {
        return $this->items ?? [];
    }

    /** 
     * @param Item $param
     * @return A
     */
    public function addItem(Item $param)
    {
        if (!is_array($this->items)) $this->items = [];
        if (!in_array($param, $this->items))
            $this->items[] = $param;
        return $this;
    }

//    /** tried with this as well
//     * @param array|null $param
//     * @return A
//     */
//    public function setItems(?array $param)
//    {
//        $this->items = $param ?? [];
//        return $this;
//    }

    /**
     * @param Item $item
     * @return A
     */
    public function removeItem(Item $item): A
    {
        if (!is_array($this->items)) $this->items = [];
        if (in_array($item, $this->items))
            unset($this->items[array_search($item, $this->items)]);
        return $this;
    }

    /**
     * @param Item $item
     * @return bool
     */
    public function hasItem(Item $item): bool
    {
        return in_array($item, $this->items);
    }
}

序列化程式看起來像這樣

        $defaultContext = [
            AbstractNormalizer::CIRCULAR_REFERENCE_HANDLER =>
                function ($articles, $format, $context) {
                    return $articles->getId();
                },
            AbstractObjectNormalizer::SKIP_NULL_VALUES => false
        ];

        $classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
        $metadataAwareNameConverter = new MetadataAwareNameConverter($classMetadataFactory);

        $encoders = [new JsonEncoder()];

       $serializer = new Serializer([
            new ArrayDenormalizer(),
            new DateTimeNormalizer(),
            new ObjectNormalizer($classMetadataFactory, $metadataAwareNameConverter, null,
                new ReflectionExtractor(), null, null, $defaultContext
            ),
        ], $encoders);

    $a = $serializer->deserialize('{ "items": null }', A::class, 'json');

我得到的錯誤items是 null

  [Symfony\Component\Serializer\Exception\InvalidArgumentException]  
  Data expected to be an array, null given.        

是否可以擁有可為空的屬性？

uj5u.com熱心網友回復：

追蹤到 Serializer 源代碼，發現了三個可能的選項來擁有一個可為空的陣列。

選項1

Remove addItem, hasItem,removeItem方法，它允許設定空值、陣列等。在我的情況下，這是不太受歡迎的解決方案。

選項 2

添加建構式也有幫助。https://github.com/symfony/serializer/blob/5.3/Normalizer/AbstractNormalizer.php#L381

    /**
     * A constructor.
     * @param array|null $items
     */
    public function __construct($items)
    {
        $this->items = $items ?? [];
    }

選項 3

處理空值的擴展ArrayDenormalizer和覆寫denormalize方法

    public function denormalize($data, string $type, string $format = null, array $context = []): array
    {
        if (null === $this->denormalizer) {
            throw new BadMethodCallException('Please set a denormalizer before calling denormalize()!');
        }
        if (!\is_array($data) && !is_null($data)) {
            throw new InvalidArgumentException('Data expected to be an array or null, ' . get_debug_type($data) . ' given.');
        }
        if (!str_ends_with($type, '[]')) {
            throw new InvalidArgumentException('Unsupported class: ' . $type);
        }
        if(is_null($data))
            return [];

        $type = substr($type, 0, -2);

        $builtinType = isset($context['key_type']) ? $context['key_type']->getBuiltinType() : null;
        foreach ($data as $key => $value) {
            if (null !== $builtinType && !('is_' . $builtinType)($key)) {
                throw new NotNormalizableValueException(sprintf('The type of the key "%s" must be "%s" ("%s" given).', $key, $builtinType, get_debug_type($key)));
            }

            $data[$key] = $this->denormalizer->denormalize($value, $type, $format, $context);
        }

        return $data;
    }

標籤：symfony json-反序列化

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