Add a denormalizer for fetching entities by id

src/Bundle/ChillMainBundle/Serializer/Normalizer/DoctrineExistingEntityNormalizer.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Chill\MainBundle\Serializer\Normalizer;
+
+use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Component\Serializer\Normalizer\AbstractNormalizer;
+use Doctrine\ORM\Mapping\ClassMetadata;
+
+
+class DoctrineExistingEntityNormalizer implements DenormalizerInterface
+{
+    private EntityManagerInterface $em;
+
+    public function __construct(EntityManagerInterface $em)
+    {
+        $this->em = $em;
+    }
+
+    public function denormalize($data, string $type, string $format = null, array $context = [])
+    {
+        if (\array_key_exists(AbstractNormalizer::OBJECT_TO_POPULATE, $context)) {
+            return $context[AbstractNormalizer::OBJECT_TO_POPULATE];
+        }
+
+        return $this->em->getRepository($type)
+            ->find($data['id']);
+    }
+
+    public function supportsDenormalization($data, string $type, string $format = null)
+    {
+        return \is_array($data)
+            && count($data) === 1 
+            && \array_key_exists('id', $data) 
+            && $this->em->getClassMetadata($type) instanceof ClassMetadata;
+    }
+    
+}