Request for help serializing union types

[gijs-blanken]

Hi!

I'm currently working on rewriting the PHP Laravel OpenAPI generator (merge request here). I was planning on using this package to handle serialization and deserialization. However, I'm running into an issue and I was hoping you could help me!

I am generating classes such as this one for OpenAPI schemas which specify an oneOf.

#[Serde\ClassSettings(renameWith: Cases::snake_case)]
class GetClientProducts200Response
{
    public function __construct(
        public \OpenAPI\Server\Model\ClientProduct|\OpenAPI\Server\Model\ClientCustomPackage $getClientProducts200ResponseInner,
    ) {}
}

And in my generated controller I will then try and serialize it using Serde:

if ($apiResult instanceof \OpenAPI\Server\Model\GetClientProducts200Response) {
    return response()->json($this->serde->serialize($apiResult, format: 'array'), 200);
}

However, Serde currently does not support serializing union types. Could you think of a workaround for this use case? I'd really like to use this package in the generator.

Thanks in advance!
Gijs

[Crell]

Union types are currently not supported, primarily because I have no idea how to do so. 😄 On serialization it would probably be feasible (ignore the type of the property, use the type of the value), but for deserialization it opens up a whole can of worms I've not figured out yet.

The preferred alternative is if you can have a property in the serialized data that indicates which class it should serialize from/deserialize to, you can give all the possible objects a common interface and put a TypeMap on it. Eg:

#[StaticTypeMap(key: 'type', map: [
        'product' => ClientProduct::class,
        'package' => ClientCustomPackage::class,
    ])]
interface ClientStuff { ... }

class ClientProduct implements ClientStuff {}
class ClientCustomPackage implements ClientStuff {}

class getClientProducts200Response {
  public ClientStuff $getClientProducts200ResponseInner;
}

Actually now that I'm reading your message again, it is serializing that you're running into. So that should work, as long as you can handle having the extra $type key in the response. (It's not currently possible to omit, I believe.)

Whether the ClientStuff interface actually has any methods or properties on it is irrelevant for Serde's purposes.

Hopefully that helps.

[gijs-blanken]

@Crell Thanks for the reply! I'm going to keep this in mind for a future update of the Laravel OpenAPI generator. I'll omit support for anyOf and oneOf for now. Great work on this package btw, coming from Rust's Serde I feel right at home :)