From 2443187bebd6c569b212df7a36cb76fdce21b5be Mon Sep 17 00:00:00 2001
From: Alan Poulain <contact@alanpoulain.eu>
Date: Wed, 9 Jul 2025 09:36:52 +0200
Subject: [PATCH] feat(serializer): handle defaultType for DiscriminatorMap

---
 src/Serializer/AbstractItemNormalizer.php | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/Serializer/AbstractItemNormalizer.php b/src/Serializer/AbstractItemNormalizer.php
index ae8475058ee..cd1f08ddc49 100644
--- a/src/Serializer/AbstractItemNormalizer.php
+++ b/src/Serializer/AbstractItemNormalizer.php
@@ -399,11 +399,13 @@ protected function getClassDiscriminatorResolvedClass(array $data, string $class
             return $class;
         }
 
-        if (!isset($data[$mapping->getTypeProperty()])) {
+        // @phpstan-ignore-next-line function.alreadyNarrowedType
+        $defaultType = method_exists($mapping, 'getDefaultType') ? $mapping->getDefaultType() : null;
+        if (!isset($data[$mapping->getTypeProperty()]) && null === $defaultType) {
             throw NotNormalizableValueException::createForUnexpectedDataType(\sprintf('Type property "%s" not found for the abstract object "%s".', $mapping->getTypeProperty(), $class), null, ['string'], isset($context['deserialization_path']) ? $context['deserialization_path'].'.'.$mapping->getTypeProperty() : $mapping->getTypeProperty());
         }
 
-        $type = $data[$mapping->getTypeProperty()];
+        $type = $data[$mapping->getTypeProperty()] ?? $defaultType;
         if (null === ($mappedClass = $mapping->getClassForType($type))) {
             throw NotNormalizableValueException::createForUnexpectedDataType(\sprintf('The type "%s" is not a valid value.', $type), $type, ['string'], isset($context['deserialization_path']) ? $context['deserialization_path'].'.'.$mapping->getTypeProperty() : $mapping->getTypeProperty(), true);
         }