Workaround: create constructor for your entity class.

Workaround: create constructor for your entity class.

That's not a solution, cause I want them to be without a value until there is actually something to store. I want to be able to avoid the NULLs all over the place. Or the empty initial value too.

If the field is not set - it should simply be ignored and not throw an error, at least this sound logical - cause this is how it works without the mappings.

A possible 'fix' I mentioned over at api-platform: api-platform/core#3974 (comment), but, as said there, I have a very hard time determining if this is just a 'fix' for the issue at hand, or a constructive fix for the Serializer/Normalizer as a whole?

IIUC using AbstractNormalizer::IGNORED_ATTRIBUTES could work per context?

from a mapping POV, should it work like ignore: {null: false, uninitialized: true}?

I don't know how that could work with mapping directly, because field initialization is dynamic during execution and mappings are static and cached most of the time.

the mapping would simply tell us to ignore must not be accessed before initialization at runtime. Or value null explicitly.

From what I understand, this seems to still be an issue when properties are declared with their type instead of annotations

This WORKS:

/*
 * @var string|null
 */
public $firstName;

This DOESN'T and still gives the error.
public ?string $firstName;

Error happens if DEEP_OBJECT_TO_POPULATE is set.
\Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer::denormalize:

            if ($attributeContext[self::DEEP_OBJECT_TO_POPULATE] ?? $this->defaultContext[self::DEEP_OBJECT_TO_POPULATE] ?? false) {
                try {
                    $attributeContext[self::OBJECT_TO_POPULATE] = $this->getAttributeValue($object, $attribute, $format, $attributeContext);
                } catch (NoSuchPropertyException $e) {
                }
            }