Support multiple product requirements on pieces

src/EventSubscriber/PieceProductSyncSubscriber.php

@@ -0,0 +1,80 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\EventSubscriber;
+
+use App\Entity\Piece;
+use App\Repository\ProductRepository;
+use Doctrine\Common\EventSubscriber;
+use Doctrine\ORM\Event\LifecycleEventArgs;
+use Doctrine\ORM\Event\PreUpdateEventArgs;
+use Doctrine\ORM\Events;
+
+/**
+ * Keep the legacy single product relation in sync with the new productIds array.
+ */
+final class PieceProductSyncSubscriber implements EventSubscriber
+{
+    public function __construct(private readonly ProductRepository $productRepository)
+    {
+    }
+
+    public function getSubscribedEvents(): array
+    {
+        return [
+            Events::prePersist,
+            Events::preUpdate,
+        ];
+    }
+
+    public function prePersist(LifecycleEventArgs $args): void
+    {
+        $entity = $args->getObject();
+        if (!$entity instanceof Piece) {
+            return;
+        }
+
+        $this->syncPrimaryProduct($entity);
+    }
+
+    public function preUpdate(PreUpdateEventArgs $args): void
+    {
+        $entity = $args->getObject();
+        if (!$entity instanceof Piece) {
+            return;
+        }
+
+        $this->syncPrimaryProduct($entity);
+
+        $em = $args->getObjectManager();
+        $meta = $em->getClassMetadata(Piece::class);
+        $em->getUnitOfWork()->recomputeSingleEntityChangeSet($meta, $entity);
+    }
+
+    private function syncPrimaryProduct(Piece $piece): void
+    {
+        $productIds = $piece->getProductIds();
+
+        if ($productIds === []) {
+            // If no explicit list is provided, keep the legacy relation as-is.
+            return;
+        }
+
+        $primaryId = $productIds[0] ?? null;
+        if (!$primaryId) {
+            $piece->setProduct(null);
+
+            return;
+        }
+
+        $currentProductId = $piece->getProduct()?->getId();
+        if ($currentProductId === $primaryId) {
+            return;
+        }
+
+        $primaryProduct = $this->productRepository->find($primaryId);
+        $piece->setProduct($primaryProduct);
+    }
+}
+