Map object to an array/JSON

[oprypkhantc]

Hey.

I'm writing an API SDK and would love to use Valinor to map requests/responses from JSON to objects and vice-versa. Mapping responses is trivial - specify a type, use JsonSource and you're done. Mapping requests is not - there are no mentions of mapping objects to JSON in the documentation, nor do I see any tests or code to support this use case.

Taking the README example, this is what I mean:

final class Country
{
    public function __construct(
        /** @var non-empty-string */
        public readonly string $name,
        
        /** @var list<City> */
        public readonly array $cities,
    ) {}
}

final class City
{
    public function __construct(
        /** @var non-empty-string */
        public readonly string $name,
        
        public readonly DateTimeZone $timeZone,
    ) {}
}

$json = <<<JSON
    {
        "name": "France",
        "cities": [
            {"name": "Paris", "timeZone": "Europe/Paris"},
            {"name": "Lyon", "timeZone": "Europe/Paris"}
        ]
    }
JSON;

$result = (new \CuyZ\Valinor\MapperBuilder())
    ->mapper()
    ->map(
        Country::class, // specify a type for generics or other non-native types
        new Country('France', [
            new City('Paris', 'Europe/Paris'), 
            new City('Lyon', 'Europe/Paris')
        ]), 
        \CuyZ\Valinor\Mapper\Source\Source::json()
    );

assert($json === $result);

I suppose this is a somewhat common use case. Most of the time when you're trying to statically type your code, you want it to be typed for both client-server and server-client communication. In case of an SDK, that's converting request DTOs to JSON to send to an external API and converting responses from JSON to DTOs. In case of an HTTP API, that's converting request JSON to DTOs and response DTOs back to JSON.

It makes sense to me that a single library would consistently (i.e. using the same mappers, the same formats, the same naming rules, the same annotations/attributes and the same logic) convert objects both to and from other formats. At least that's how other languages' competitors do it - say Java's serializer libraries all allow bi-directional conversion.

How feasible is this to implement? This issue is forcing me to use one of the overall worse alternatives which I would love not to be doing. I can help with the implementation, but only if there's a real chance for it to be merged. That looks like a good chunk of work that I really don't want to go to waste :)

Thanks.

[romm]

Hello @oprypkhantc, I've just submitted a discussion in the repository, I'd love to have your input on it, to better understand what people need. 😊