feat: Avoid eager joining back to the just visited parent

Author: carlobeltrame

src/Core/Bridge/Doctrine/Orm/Extension/EagerLoadingExtension.php

@@ -28,6 +28,7 @@
 use ApiPlatform\Exception\RuntimeException;
 use ApiPlatform\Metadata\ApiProperty;
 use ApiPlatform\Metadata\Resource\Factory\ResourceMetadataCollectionFactoryInterface;
+use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\Mapping\ClassMetadataInfo;
 use Doctrine\ORM\Query\Expr\Join;
 use Doctrine\ORM\QueryBuilder;
@@ -167,7 +168,7 @@ private function apply(bool $collection, QueryBuilder $queryBuilder, QueryNameGe
      *
      * @throws RuntimeException when the max number of joins has been reached
      */
-    private function joinRelations(QueryBuilder $queryBuilder, QueryNameGeneratorInterface $queryNameGenerator, string $resourceClass, bool $forceEager, bool $fetchPartial, string $parentAlias, array $options = [], array $normalizationContext = [], bool $wasLeftJoin = false, int &$joinCount = 0, int $currentDepth = null)
+    private function joinRelations(QueryBuilder $queryBuilder, QueryNameGeneratorInterface $queryNameGenerator, string $resourceClass, bool $forceEager, bool $fetchPartial, string $parentAlias, array $options = [], array $normalizationContext = [], bool $wasLeftJoin = false, int &$joinCount = 0, int $currentDepth = null, string $parentAssociation = null)
     {
         if ($joinCount > $this->maxJoins) {
             throw new RuntimeException('The total number of joined relations has exceeded the specified maximum. Raise the limit if necessary with the "api_platform.eager_loading.max_joins" configuration key (https://api-platform.com/docs/core/performance/#eager-loading), or limit the maximum serialization depth using the "enable_max_depth" option of the Symfony serializer (https://symfony.com/doc/current/components/serializer.html#handling-serialization-depth).');
@@ -232,6 +233,16 @@ private function joinRelations(QueryBuilder $queryBuilder, QueryNameGeneratorInt
                 continue;
             }
 
+            // Avoid joining back to the parent that we just came from, but only on *ToOne relations
+            if (
+                null !== $parentAssociation &&
+                isset($mapping['inversedBy']) &&
+                $mapping['inversedBy'] === $parentAssociation &&
+                $mapping['type'] & ClassMetadata::TO_ONE
+            ) {
+                continue;
+            }
+
             $existingJoin = QueryBuilderHelper::getExistingJoin($queryBuilder, $parentAlias, $association);
 
             if (null !== $existingJoin) {
@@ -276,7 +287,7 @@ private function joinRelations(QueryBuilder $queryBuilder, QueryNameGeneratorInt
                 }
             }
 
-            $this->joinRelations($queryBuilder, $queryNameGenerator, $mapping['targetEntity'], $forceEager, $fetchPartial, $associationAlias, $options, $childNormalizationContext, $isLeftJoin, $joinCount, $currentDepth);
+            $this->joinRelations($queryBuilder, $queryNameGenerator, $mapping['targetEntity'], $forceEager, $fetchPartial, $associationAlias, $options, $childNormalizationContext, $isLeftJoin, $joinCount, $currentDepth, $association);
         }
     }