fix: error when mapping null to existing target (#248)

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * fix: rethrow our exceptions in `writeTargetProperty`, fix confusing error
   message
+* fix: error when mapping null to existing target
 
 ## 1.13.2
 

src/MainTransformer/Exception/TransformerReturnsUnexpectedValueException.php

@@ -14,6 +14,7 @@
 namespace Rekalogika\Mapper\MainTransformer\Exception;
 
 use Rekalogika\Mapper\Context\Context;
+use Rekalogika\Mapper\Debug\TraceableTransformer;
 use Rekalogika\Mapper\Exception\UnexpectedValueException;
 use Rekalogika\Mapper\Transformer\MixedType;
 use Rekalogika\Mapper\Transformer\TransformerInterface;
@@ -29,6 +30,10 @@ public function __construct(
         TransformerInterface $transformer,
         Context $context,
     ) {
+        if ($transformer instanceof TraceableTransformer) {
+            $transformer = $transformer->getDecorated();
+        }
+
         $message = \sprintf(
             'Trying to map source type "%s" to target type "%s", but the assigned transformer "%s" returns an unexpected type "%s".',
             get_debug_type($source),

src/Transformer/Exception/NullSourceButMandatoryTargetException.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Transformer\Exception;
+
+use Rekalogika\Mapper\Context\Context;
+use Rekalogika\Mapper\Exception\RuntimeException;
+use Rekalogika\Mapper\Util\TypeFactory;
+use Rekalogika\Mapper\Util\TypeUtil;
+use Symfony\Component\PropertyInfo\Type;
+
+class NullSourceButMandatoryTargetException extends RuntimeException
+{
+    public function __construct(
+        ?Type $targetType,
+        ?\Throwable $previous = null,
+        ?Context $context = null,
+    ) {
+        parent::__construct(
+            message: \sprintf(
+                'The source is null, the target is mandatory & expected to be of type "%s". But no transformer is able to handle this case.',
+                TypeUtil::getTypeString($targetType ?? TypeFactory::mixed()),
+            ),
+            previous: $previous,
+            context: $context,
+        );
+    }
+}

src/Transformer/Implementation/NullTransformer.php

@@ -15,6 +15,7 @@
 
 use Rekalogika\Mapper\Context\Context;
 use Rekalogika\Mapper\Exception\InvalidArgumentException;
+use Rekalogika\Mapper\Transformer\Exception\NullSourceButMandatoryTargetException;
 use Rekalogika\Mapper\Transformer\TransformerInterface;
 use Rekalogika\Mapper\Transformer\TypeMapping;
 use Rekalogika\Mapper\Util\TypeCheck;
@@ -31,6 +32,21 @@ public function transform(
         ?Type $targetType,
         Context $context,
     ): mixed {
+        // if the source is null & the target is an object, ignore it by
+        // returning the existing target. if the existing target is not already
+        // an object, throw an exception
+
+        if (TypeCheck::isObject($targetType)) {
+            if ($target === null) {
+                throw new NullSourceButMandatoryTargetException(
+                    targetType: $targetType,
+                    context: $context,
+                );
+            }
+
+            return $target;
+        }
+
         if ($target !== null) {
             throw new InvalidArgumentException('Target must be null');
         }
@@ -70,6 +86,7 @@ public function getSupportedTransformation(): iterable
         yield new TypeMapping(TypeFactory::null(), TypeFactory::float());
         yield new TypeMapping(TypeFactory::null(), TypeFactory::bool());
         yield new TypeMapping(TypeFactory::null(), TypeFactory::array());
+        yield new TypeMapping(TypeFactory::null(), TypeFactory::object(), true);
         yield new TypeMapping(TypeFactory::mixed(), TypeFactory::null());
     }
 }

src/Util/TypeUtil.php

@@ -21,6 +21,7 @@
 use Rekalogika\Mapper\Tests\IntegrationTest\MapPropertyPathTest;
 use Rekalogika\Mapper\Tests\UnitTest\Util\TypeUtil2Test;
 use Rekalogika\Mapper\Tests\UnitTest\Util\TypeUtilTest;
+use Rekalogika\Mapper\Transformer\Exception\NullSourceButMandatoryTargetException;
 use Rekalogika\Mapper\Transformer\MixedType;
 use Rekalogika\Mapper\TypeResolver\Implementation\TypeResolver;
 use Symfony\Component\PropertyInfo\Type;
@@ -257,6 +258,7 @@ public static function getDebugType(null|Type|MixedType|array $type): string
         TypeUtilTest::class,
         TraceData::class,
         MapPropertyPathTest::class,
+        NullSourceButMandatoryTargetException::class,
     )]
     public static function getTypeString(Type|MixedType $type): string
     {

tests/config/rekalogika-mapper/generated-mappings.php

@@ -693,6 +693,18 @@
         target: \Rekalogika\Mapper\Tests\Fixtures\Money\ObjectWithIntegerBackedMoneyProperty::class
     );
 
+    $mappingCollection->addObjectMapping(
+        // tests/src/IntegrationTest/NullSourceTest.php on line 36
+        source: \Rekalogika\Mapper\Tests\Fixtures\NullSource\Source::class,
+        target: \Rekalogika\Mapper\Tests\Fixtures\NullSource\TargetString::class
+    );
+
+    $mappingCollection->addObjectMapping(
+        // tests/src/IntegrationTest/NullSourceTest.php on line 27
+        source: \Rekalogika\Mapper\Tests\Fixtures\NullSource\Source::class,
+        target: \Rekalogika\Mapper\Tests\Fixtures\NullSource\TargetUuid::class
+    );
+
     $mappingCollection->addObjectMapping(
         // tests/src/IntegrationTest/ObjectKeysTest.php on line 27
         source: \Rekalogika\Mapper\Tests\Fixtures\ObjectKeys\RelationshipMap::class,

tests/src/Fixtures/NullSource/Source.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\NullSource;
+
+final readonly class Source
+{
+    // @phpstan-ignore return.unusedType
+    public function getProperty(): ?string
+    {
+        return null;
+    }
+}

tests/src/Fixtures/NullSource/TargetString.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\NullSource;
+
+use Symfony\Component\Uid\Uuid;
+
+class TargetString
+{
+    private string $property;
+
+    public function __construct()
+    {
+        $this->property = (string) Uuid::v7();
+    }
+
+    public function getProperty(): string
+    {
+        return $this->property;
+    }
+}

tests/src/Fixtures/NullSource/TargetUuid.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\NullSource;
+
+use Symfony\Component\Uid\Uuid;
+
+class TargetUuid
+{
+    private Uuid $property;
+
+    public function __construct()
+    {
+        $this->property = Uuid::v7();
+    }
+
+    public function getProperty(): Uuid
+    {
+        return $this->property;
+    }
+}

tests/src/IntegrationTest/ConstructorTest.php

@@ -13,7 +13,6 @@
 
 namespace Rekalogika\Mapper\Tests\IntegrationTest;
 
-use Rekalogika\Mapper\MainTransformer\Exception\CannotFindTransformerException;
 use Rekalogika\Mapper\Tests\Common\FrameworkTestCase;
 use Rekalogika\Mapper\Tests\Fixtures\Constructor\ObjectWithConstructorAndExtraMandatoryArgumentDto;
 use Rekalogika\Mapper\Tests\Fixtures\Constructor\ObjectWithConstructorAndPropertiesDto;
@@ -25,6 +24,7 @@
 use Rekalogika\Mapper\Tests\Fixtures\Scalar\ObjectWithScalarPropertiesAndAdditionalNullProperty;
 use Rekalogika\Mapper\Transformer\Exception\ClassNotInstantiableException;
 use Rekalogika\Mapper\Transformer\Exception\InstantiationFailureException;
+use Rekalogika\Mapper\Transformer\Exception\NullSourceButMandatoryTargetException;
 
 class ConstructorTest extends FrameworkTestCase
 {
@@ -91,7 +91,7 @@ public function testFromEmptyStdClassToMandatoryArguments(): void
 
     public function testFromEmptyStdClassToMandatoryArgumentsThatCannotBeCastFromNull(): void
     {
-        $this->expectException(CannotFindTransformerException::class);
+        $this->expectException(NullSourceButMandatoryTargetException::class);
         $source = new \stdClass();
         $this->mapper->map($source, ObjectWithMandatoryConstructorThatCannotBeCastFromNullDto::class);
     }

tests/src/IntegrationTest/NullSourceTest.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\IntegrationTest;
+
+use Rekalogika\Mapper\Tests\Common\FrameworkTestCase;
+use Rekalogika\Mapper\Tests\Fixtures\NullSource\Source;
+use Rekalogika\Mapper\Tests\Fixtures\NullSource\TargetString;
+use Rekalogika\Mapper\Tests\Fixtures\NullSource\TargetUuid;
+
+class NullSourceTest extends FrameworkTestCase
+{
+    public function testNullSourceToUuid(): void
+    {
+        $source = new Source();
+        $target = new TargetUuid();
+        $newTarget = $this->mapper->map($source, $target);
+
+        $this->assertSame($target, $newTarget);
+    }
+
+    public function testNullSourceToString(): void
+    {
+        $source = new Source();
+        $target = new TargetString();
+        $newTarget = $this->mapper->map($source, $target);
+
+        $this->assertSame($target, $newTarget);
+    }
+
+}