fix(metadata): fix POST on subresource (#5734)

Author: vincentchalamon

CreateProvider.php

@@ -19,6 +19,7 @@
 use ApiPlatform\Metadata\Link;
 use ApiPlatform\Metadata\Operation;
 use ApiPlatform\Metadata\Post;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 use Symfony\Component\PropertyAccess\PropertyAccess;
 use Symfony\Component\PropertyAccess\PropertyAccessorInterface;
 
@@ -59,12 +60,17 @@ public function provide(Operation $operation, array $uriVariables = [], array $c
         }
 
         $relation = $this->decorated->provide(new Get(uriVariables: $relationUriVariables, class: $relationClass), $uriVariables);
+        if (!$relation) {
+            throw new NotFoundHttpException('Not Found');
+        }
+
         try {
             $resource = new ($operation->getClass());
         } catch (\Throwable $e) {
             throw new RuntimeException(sprintf('An error occurred while trying to create an instance of the "%s" resource. Consider writing your own "%s" implementation and setting it as `provider` on your operation instead.', $operation->getClass(), ProviderInterface::class), 0, $e);
         }
-        $this->propertyAccessor->setValue($resource, $key, $relation);
+        $property = $operationUriVariables[$key]->getToProperty() ?? $key;
+        $this->propertyAccessor->setValue($resource, $property, $relation);
 
         return $resource;
     }