Throw LogicException when readOnly is used with toOne associations

Author: JanTvrdik

README.md

@@ -101,7 +101,7 @@ foreach ($categories as $category) {
 
 - **Batch Size:** Set a custom batch size for preloading to optimize memory usage.
 - **Max Fetch Join Same Field Count:** Define the maximum number of join fetches allowed per field.
-- **Read Only:** Mark preloaded entities as read-only to disable change tracking and improve performance.
+- **Read Only:** Mark preloaded entities as read-only to disable change tracking and improve performance (only supported for `#[OneToMany]` and `#[ManyToMany]` associations).
 
 ```php
 $preloader->preload(

src/EntityPreloader.php

@@ -64,22 +64,26 @@ public function preload(
             throw new LogicException('Preloading of indexed associations is not supported');
         }
 
+        $isToOne = $associationMapping['type'] === ClassMetadata::ONE_TO_ONE
+            || $associationMapping['type'] === ClassMetadata::MANY_TO_ONE;
+
+        if ($readOnly && $isToOne) {
+            throw new LogicException('The readOnly option is not supported for toOne associations');
+        }
+
         $maxFetchJoinSameFieldCount ??= 1;
         $sourceEntities = $this->loadProxies(
             $sourceClassMetadata,
             $sourceEntities,
             $batchSize ?? self::PRELOAD_ENTITY_DEFAULT_BATCH_SIZE,
             $maxFetchJoinSameFieldCount,
-            $readOnly,
         );
 
-        $preloader = match ($associationMapping['type']) {
-            ClassMetadata::ONE_TO_ONE, ClassMetadata::MANY_TO_ONE => $this->preloadToOne(...),
-            ClassMetadata::ONE_TO_MANY, ClassMetadata::MANY_TO_MANY => $this->preloadToMany(...),
-            default => throw new LogicException("Unsupported association mapping type {$associationMapping['type']}"),
-        };
+        if ($isToOne) {
+            return $this->preloadToOne($sourceEntities, $sourceClassMetadata, $sourcePropertyName, $targetClassMetadata, $batchSize, $maxFetchJoinSameFieldCount);
+        }
 
-        return $preloader($sourceEntities, $sourceClassMetadata, $sourcePropertyName, $targetClassMetadata, $batchSize, $maxFetchJoinSameFieldCount, $readOnly);
+        return $this->preloadToMany($sourceEntities, $sourceClassMetadata, $sourcePropertyName, $targetClassMetadata, $batchSize, $maxFetchJoinSameFieldCount, $readOnly);
     }
 
     /**
@@ -122,7 +126,6 @@ private function loadProxies(
         array $entities,
         int $batchSize,
         int $maxFetchJoinSameFieldCount,
-        bool $readOnly,
     ): array
     {
         $identifierAccessor = $this->getSingleIdPropertyAccessor($classMetadata); // e.g. Order::$id reflection
@@ -146,7 +149,7 @@ private function loadProxies(
         }
 
         foreach (array_chunk($uninitializedIds, $batchSize) as $idsChunk) {
-            $this->loadEntitiesBy($classMetadata, $identifierName, $classMetadata, $idsChunk, $maxFetchJoinSameFieldCount, readOnly: $readOnly);
+            $this->loadEntitiesBy($classMetadata, $identifierName, $classMetadata, $idsChunk, $maxFetchJoinSameFieldCount);
         }
 
         return array_values($uniqueEntities);
@@ -383,7 +386,6 @@ private function preloadToOne(
         ClassMetadata $targetClassMetadata,
         ?int $batchSize,
         int $maxFetchJoinSameFieldCount,
-        bool $readOnly,
     ): array
     {
         $sourcePropertyAccessor = $this->getPropertyAccessor($sourceClassMetadata, $sourcePropertyName); // e.g. Item::$order reflection
@@ -405,7 +407,7 @@ private function preloadToOne(
             $targetEntities[] = $targetEntity;
         }
 
-        return $this->loadProxies($targetClassMetadata, $targetEntities, $batchSize, $maxFetchJoinSameFieldCount, $readOnly);
+        return $this->loadProxies($targetClassMetadata, $targetEntities, $batchSize, $maxFetchJoinSameFieldCount);
     }
 
     /**

tests/EntityPreloadBlogManyHasManyTest.php

@@ -125,6 +125,12 @@ public function testManyHasManyWithPreloadReadOnly(DbalType $primaryKey): void
 
         self::assertCount(25, $tags);
 
+        // Verify that preloaded tags are marked as read-only
+        $unitOfWork = $this->getEntityManager()->getUnitOfWork();
+        foreach ($tags as $tag) {
+            self::assertTrue($unitOfWork->isReadOnly($tag), 'Tag should be marked as read-only');
+        }
+
         self::assertAggregatedQueries([
             ['count' => 1, 'query' => 'SELECT * FROM article t0'],
             ['count' => 1, 'query' => 'SELECT * FROM article a0_ INNER JOIN article_tag a2_ ON a0_.id = a2_.article_id INNER JOIN tag t1_ ON t1_.id = a2_.tag_id WHERE a0_.id IN (?, ?, ?, ?, ?)'],

tests/EntityPreloadBlogManyHasOneTest.php

@@ -119,19 +119,17 @@ public function testManyHasOneWithPreload(DbalType $primaryKey): void
     }
 
     #[DataProvider('providePrimaryKeyTypes')]
-    public function testManyHasOneWithPreloadReadOnly(DbalType $primaryKey): void
+    public function testManyHasOneWithPreloadReadOnlyThrowsException(DbalType $primaryKey): void
     {
         $this->createDummyBlogData($primaryKey, categoryCount: 5, articleInEachCategoryCount: 5);
 
         $articles = $this->getEntityManager()->getRepository(Article::class)->findAll();
-        $categories = $this->getEntityPreloader()->preload($articles, 'category', readOnly: true);
 
-        self::assertCount(5, $categories);
-
-        self::assertAggregatedQueries([
-            ['count' => 1, 'query' => 'SELECT * FROM article t0'],
-            ['count' => 1, 'query' => 'SELECT * FROM category c0_ WHERE c0_.id IN (?, ?, ?, ?, ?)'],
-        ]);
+        self::assertException(
+            \LogicException::class,
+            'The readOnly option is not supported for toOne associations',
+            fn () => $this->getEntityPreloader()->preload($articles, 'category', readOnly: true),
+        );
     }
 
     /**

tests/EntityPreloadBlogOneHasManyTest.php

@@ -149,6 +149,12 @@ public function testOneHasManyWithPreloadReadOnly(DbalType $primaryKey): void
 
         self::assertCount(25, $articles);
 
+        // Verify that preloaded articles are marked as read-only
+        $unitOfWork = $this->getEntityManager()->getUnitOfWork();
+        foreach ($articles as $article) {
+            self::assertTrue($unitOfWork->isReadOnly($article), 'Article should be marked as read-only');
+        }
+
         self::assertAggregatedQueries([
             ['count' => 1, 'query' => 'SELECT * FROM category t0'],
             ['count' => 1, 'query' => 'SELECT * FROM article a0_ WHERE a0_.category_id IN (?, ?, ?, ?, ?)'],