@derrabus You're probably very busy, but I'm really curious to hear your feedback on this 😊

@mtarld @nicolas-grekas Friendly ping to pick your brain on this topic, since you worked on the discriminator mapping in #52681. I'm curious to hear if my approach makes sense, or that I should investigate time in finding an alternative solution. Any advice is much appreciated, thanks 😊

Thanks for the help @mtarld and @nicolas-grekas 🎉

The failing test is unrelated to these changes.

Thank you @ruudk.

Hi @nicolas-grekas

I probably got similar problem at symfony 7.1.5

Test Case:

<?php

declare(strict_types=1);

namespace App\Test;

use Symfony\Component\Serializer\Attribute\DiscriminatorMap;
use Symfony\Component\Serializer\Attribute\Ignore;

#[DiscriminatorMap(
    typeProperty: 'type',
    mapping: [
        'base_payload' => BasePayload::class,
        'new_payload' => ExamplePayload::class,
    ],
)]
readonly class BasePayload
{
    public function __construct(
        protected string $a,
    ) {
    }

    public function getA(): string
    {
        return $this->a;
    }

    #[Ignore]
    public function isAString(): bool
    {
        return is_string($this->a);
    }

}

<?php

declare(strict_types=1);

namespace App\Test;

final readonly class ExamplePayload extends BasePayload
{
    public function __construct(
        string $a,
        protected string $b,
    ) {
        parent::__construct($a);
    }

    public function getB(): string
    {
        return $this->b;
    }
}

Runs this:
$payload = new BasePayload('string');

$serialized = $this->serializer->serialize($payload, 'json');

    I got 

But then i drop Ignore attribute - it passes!!

{"type":"base_payload","a":"string","aString":true}

@VitekSkrip please give this PR a try and create a new issue if it doesn't fix it for you then.

@VitekSkrip please give this PR a try and create a new issue if it doesn't fix it for you then.

what version of symfony or symfony/serializer should i use then?

@VitekSkrip This was just merged to 6.4.x.dev. It will take some time before it is merged to 7.2 and 7.3. Since you are on 7.1 you won't get it, unless you upgrade.