[TwigComponent] Defaulted options of a resolver are removed from the passed data when they're not set

[HugoLandrin]

When resolving your data through an OptionsResolver in a PreMount event of a twig component, options that are set to have a default value get erased from the data array passed to the rendered twig template when they have no data attached.

Important

I am not using class props.

The component class:

#[AsTwigComponent('button')]
class Button
{
    #[PreMount]
    public function preMount(array $data): array
    {
        $resolver = (new OptionsResolver());

        $resolver
            ->define('path')
            ->default(null)
            ->allowedTypes('string', 'null')

        return $resolver->resolve($data);
    }
}

The component Twig file:

{% if path is not null %}
    <a href="{{ path }}"
{% else %}
    <button
{% endif %}
    ...
{% if path is not null %}
    </a>
{% else %}
    </button>
{% endif %}

Error: Variable "path" does not exist in _components/button.html.twig

Important

This does not occur when manually setting the parameter when calling the component

Resolved options should retain their defaulted values when they are set to null, just like any other use case of the OptionsResolver.

[Kocal]

Hi, shouldn't you return + $data like shown on https://symfony.com/bundles/ux-twig-component/current/index.html#premount-hook, or did I misunderstand?

[smnandre]

Resolved options should retain their defaulted values when they are set to null

I am not using class props.

Resolved option do retain their defaulted values. But resolved options and mounted props are two different things, and as you said, you have no props, so.... 🤷