[LiveComponent] Anonymous component rendering problem ?

[anatoly-pashin-axon21]

Hi. I'm not able to present a minimal reproducer, but we have a problem with an anonymous component rendering.

The problem is happening only for the event handling render (\Symfony\UX\LiveComponent\Attribute\PreReRender -> \Symfony\UX\LiveComponent\ComponentToolsTrait::emit -> POST https://redacted/en/_components/sylius_shop:product:summary/eventNameRedacted)

I have reviewed the code and I see an issue with the anonymous components metadata handling.

\Symfony\UX\LiveComponent\Metadata\LiveComponentMetadataFactory::getMetadata:

public function getMetadata(string $name): LiveComponentMetadata
{
    // some not related code removed

    $componentMetadata = $this->componentFactory->metadataFor($name);

    // here the getClass() is called:
    $reflectionClass = new \ReflectionClass($componentMetadata->getClass());

    // some not related code removed
}

\Symfony\UX\TwigComponent\ComponentFactory::metadataFor:

public function metadataFor(string $name): ComponentMetadata
{
    // some not related code removed

    if ($template = $this->componentTemplateFinder->findAnonymousComponentTemplate($name)) {
        $this->config[$name] = [
            'key' => $name,
            'template' => $template,
        ];

        // here we return the metadata with only two keys in the config (key, template):
        return new ComponentMetadata($this->config[$name]);
    }

As you can see, it tries to read "class", but there is no class defined for the anonymous components. There are only key and template defined for them. I believe the code is missing for the AnonymousComponent special case handling.

We use the latest versions of symfony/ux-live-component symfony/ux-twig-component libs.

[smnandre]

Anonymous component cannot be LiveComponent so not sure what is going on here 🤔

[anatoly-pashin-axon21]

You can see from the trace that there happens a twig component creation (ux-twig/ComponentRenderer). It dispatches an event, that is handled by ux-live/InterceptChildComponentRender that tries to get metadata.class. So it's just an error in the code.

I was able to fix this is our project by adding a missing check for the AnonymousComponent in the method I mentioned earlier.

[smnandre]

@anatoly-pashin-axon21

I am stating - again - that I don't get how and why a LiveComponentMetadataFactory would try to create metadata for a non-live component. Not saying it does not happen. But this is not a scenario I understand right now.

Without a simple reproducer (not just an exception screenshot, where we can see lots of other things coming in play).. we cannot investigate nor find a solution if there is a bug we missed (this is very possible).

I'm sure you can understand that without observing your problem in simple and isolated conditions, we cannot apply the code change you suggest.