vendor/symfony/ux-live-component/src/EventListener/InterceptChildComponentRenderSubscriber.php line 47

  1. <?php
  3. /*
  4.  * This file is part of the Symfony package.
  5.  *
  6.  * (c) Fabien Potencier <fabien@symfony.com>
  7.  *
  8.  * For the full copyright and license information, please view the LICENSE
  9.  * file that was distributed with this source code.
  10.  */
  12. namespace Symfony\UX\LiveComponent\EventListener;
  14. use Symfony\Component\EventDispatcher\EventSubscriberInterface;
  15. use Symfony\UX\LiveComponent\LiveComponentHydrator;
  16. use Symfony\UX\LiveComponent\Twig\DeterministicTwigIdCalculator;
  17. use Symfony\UX\LiveComponent\Util\FingerprintCalculator;
  18. use Symfony\UX\LiveComponent\Util\JsonUtil;
  19. use Symfony\UX\LiveComponent\Util\TwigAttributeHelper;
  20. use Symfony\UX\TwigComponent\ComponentFactory;
  21. use Symfony\UX\TwigComponent\ComponentStack;
  22. use Symfony\UX\TwigComponent\Event\PreCreateForRenderEvent;
  24. /**
  25.  * Responsible for rendering children as empty elements during a re-render.
  26.  *
  27.  * @author Ryan Weaver <ryan@symfonycasts.com>
  28.  *
  29.  * @experimental
  30.  *
  31.  * @internal
  32.  */
  33. class InterceptChildComponentRenderSubscriber implements EventSubscriberInterface
  34. {
  35.     public const CHILDREN_FINGERPRINTS_METADATA_KEY = 'children_fingerprints';
  37.     public function __construct(
  38.         private ComponentStack $componentStack,
  39.         private DeterministicTwigIdCalculator $deterministicTwigIdCalculator,
  40.         private FingerprintCalculator $fingerprintCalculator,
  41.         private TwigAttributeHelper $twigAttributeHelper,
  42.         private ComponentFactory $componentFactory,
  43.         private LiveComponentHydrator $liveComponentHydrator,
  44.     ) {
  45.     }
  47.     public function preComponentCreated(PreCreateForRenderEvent $event): void
  48.     {
  49.         // if there is already a component, that's a parent. Else, this is not a child.
  50.         if (!$this->componentStack->getCurrentComponent()) {
  51.             return;
  52.         }
  54.         $parentComponent = $this->componentStack->getCurrentComponent();
  55.         if (!$parentComponent->hasExtraMetadata(self::CHILDREN_FINGERPRINTS_METADATA_KEY)) {
  56.             return;
  57.         }
  59.         $childFingerprints = $parentComponent->getExtraMetadata(self::CHILDREN_FINGERPRINTS_METADATA_KEY);
  61.         // get the deterministic id for this child, but without incrementing the counter yet
  62.         $deterministicId = $this->deterministicTwigIdCalculator->calculateDeterministicId(increment: false);
  63.         if (!isset($childFingerprints[$deterministicId])) {
  64.             // child fingerprint wasn't set, it is likely a new child, allow it to render fully
  65.             return;
  66.         }
  68.         // increment the internal counter now to keep "counter" consistency if we're
  69.         // in a loop of children being rendered on the same line
  70.         // we need to do this because this component will *not* ever hit
  71.         // AddLiveAttributesSubscriber where the counter is normally incremented
  72.         $this->deterministicTwigIdCalculator->calculateDeterministicId(increment: true);
  74.         $newPropsFingerprint = $this->fingerprintCalculator->calculateFingerprint($event->getProps());
  76.         if ($childFingerprints[$deterministicId] === $newPropsFingerprint) {
  77.             // the props passed to create this child have *not* changed
  78.             // return an empty element so the frontend knows to keep the current child
  80.             $rendered = sprintf(
  81.                 '<div data-live-id="%s"></div>',
  82.                 $this->twigAttributeHelper->escapeAttribute($deterministicId)
  83.             );
  84.             $event->setRenderedString($rendered);
  86.             return;
  87.         }
  89.         /*
  90.          * The props passed to create this child HAVE changed.
  91.          * Send back a fake element with:
  92.          *      * data-live-id
  93.          *      * data-live-fingerprint-value (new fingerprint)
  94.          *      * data-live-props-value (new dehydrated props)
  95.          */
  96.         $mounted = $this->componentFactory->create($event->getName(), $event->getProps());
  97.         $dehydratedComponent = $this->liveComponentHydrator->dehydrate($mounted);
  99.         $rendered = sprintf(
  100.             '<div data-live-id="%s" data-live-fingerprint-value="%s" data-live-props-value="%s"></div>',
  101.             $this->twigAttributeHelper->escapeAttribute($deterministicId),
  102.             $this->twigAttributeHelper->escapeAttribute($newPropsFingerprint),
  103.             $this->twigAttributeHelper->escapeAttribute(JsonUtil::encodeObject($dehydratedComponent->getProps()))
  104.         );
  105.         $event->setRenderedString($rendered);
  106.     }
  108.     public static function getSubscribedEvents(): array
  109.     {
  110.         return [
  111.             PreCreateForRenderEvent::class => 'preComponentCreated',
  112.         ];
  113.     }
  114. }