Fix/4372 skip null values in hal

src/Hal/Serializer/ItemNormalizer.php

@@ -305,14 +305,16 @@ private function populateRelation(array $data, object $object, ?string $format,
 
             $attributeValue = $this->getAttributeValue($object, $relation['name'], $format, $childContext);
 
-            if (empty($attributeValue)) {
+            if (empty($attributeValue) && ($context[self::SKIP_NULL_TO_ONE_RELATIONS] ?? $this->defaultContext[self::SKIP_NULL_TO_ONE_RELATIONS] ?? true)) {
                 continue;
             }
 
             if ('one' === $relation['cardinality']) {
                 if ('links' === $type) {
-                    $data[$key][$relationName]['href'] = $this->getRelationIri($attributeValue);
-                    continue;
+                    if (null !== $attributeValue) {
+                        $data[$key][$relationName]['href'] = $this->getRelationIri($attributeValue);
+                        continue;
+                    }
                 }
 
                 $data[$key][$relationName] = $attributeValue;

src/Serializer/AbstractItemNormalizer.php

@@ -65,6 +65,11 @@ abstract class AbstractItemNormalizer extends AbstractObjectNormalizer
     use ContextTrait;
     use InputOutputMetadataTrait;
     use OperationContextTrait;
+    /**
+     * Flag to control whether to one relation with the value `null` should be output
+     * when normalizing or omitted.
+     */
+    public const SKIP_NULL_TO_ONE_RELATIONS = 'skip_null_to_one_relations';
 
     protected PropertyAccessorInterface $propertyAccessor;
     protected array $localCache = [];

src/Serializer/SerializerContextBuilder.php

@@ -60,6 +60,7 @@ public function createFromRequest(Request $request, bool $normalization, ?array
         $context['operation'] = $operation;
         $context['resource_class'] = $attributes['resource_class'];
         $context['skip_null_values'] ??= true;
+        $context[AbstractItemNormalizer::SKIP_NULL_TO_ONE_RELATIONS] ??= true;
         $context['iri_only'] ??= false;
         $context['request_uri'] = $request->getRequestUri();
         $context['uri'] = $request->getUri();

src/Serializer/Tests/SerializerContextBuilderTest.php

@@ -67,42 +67,42 @@ public function testCreateFromRequest(): void
     {
         $request = Request::create('/foos/1');
         $request->attributes->replace(['_api_resource_class' => 'Foo', '_api_operation_name' => 'get', '_api_format' => 'xml', '_api_mime_type' => 'text/xml']);
-        $expected = ['foo' => 'bar', 'operation_name' => 'get',  'resource_class' => 'Foo', 'request_uri' => '/foos/1', 'uri' => 'http://localhost/foos/1', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['foo' => 'bar', 'operation_name' => 'get',  'resource_class' => 'Foo', 'request_uri' => '/foos/1', 'uri' => 'http://localhost/foos/1', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest($request, true));
 
         $request = Request::create('/foos');
         $request->attributes->replace(['_api_resource_class' => 'Foo', '_api_operation_name' => 'get_collection', '_api_format' => 'xml', '_api_mime_type' => 'text/xml']);
-        $expected = ['foo' => 'bar', 'operation_name' => 'get_collection',  'resource_class' => 'Foo', 'request_uri' => '/foos', 'uri' => 'http://localhost/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation->withName('get_collection'), 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata',  'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['foo' => 'bar', 'operation_name' => 'get_collection',  'resource_class' => 'Foo', 'request_uri' => '/foos', 'uri' => 'http://localhost/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation->withName('get_collection'), 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata',  'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest($request, true));
 
         $request = Request::create('/foos/1');
         $request->attributes->replace(['_api_resource_class' => 'Foo', '_api_operation_name' => 'get', '_api_format' => 'xml', '_api_mime_type' => 'text/xml']);
-        $expected = ['bar' => 'baz', 'operation_name' => 'get',  'resource_class' => 'Foo', 'request_uri' => '/foos/1', 'api_allow_update' => false, 'uri' => 'http://localhost/foos/1', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['bar' => 'baz', 'operation_name' => 'get',  'resource_class' => 'Foo', 'request_uri' => '/foos/1', 'api_allow_update' => false, 'uri' => 'http://localhost/foos/1', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest($request, false));
 
         $request = Request::create('/foos', 'POST');
         $request->attributes->replace(['_api_resource_class' => 'Foo', '_api_operation_name' => 'post', '_api_format' => 'xml', '_api_mime_type' => 'text/xml']);
-        $expected = ['bar' => 'baz', 'operation_name' => 'post',  'resource_class' => 'Foo', 'request_uri' => '/foos', 'api_allow_update' => false, 'uri' => 'http://localhost/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation->withName('post'), 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['bar' => 'baz', 'operation_name' => 'post',  'resource_class' => 'Foo', 'request_uri' => '/foos', 'api_allow_update' => false, 'uri' => 'http://localhost/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation->withName('post'), 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest($request, false));
 
         $request = Request::create('/foos', 'PUT');
         $request->attributes->replace(['_api_resource_class' => 'Foo', '_api_operation_name' => 'put', '_api_format' => 'xml', '_api_mime_type' => 'text/xml']);
-        $expected = ['bar' => 'baz', 'operation_name' => 'put', 'resource_class' => 'Foo', 'request_uri' => '/foos', 'api_allow_update' => true, 'uri' => 'http://localhost/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => (new Put(name: 'put'))->withOperation($this->operation), 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['bar' => 'baz', 'operation_name' => 'put', 'resource_class' => 'Foo', 'request_uri' => '/foos', 'api_allow_update' => true, 'uri' => 'http://localhost/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => (new Put(name: 'put'))->withOperation($this->operation), 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest($request, false));
 
         $request = Request::create('/bars/1/foos');
         $request->attributes->replace(['_api_resource_class' => 'Foo', '_api_operation_name' => 'get', '_api_format' => 'xml', '_api_mime_type' => 'text/xml']);
-        $expected = ['bar' => 'baz', 'operation_name' => 'get', 'resource_class' => 'Foo', 'request_uri' => '/bars/1/foos', 'api_allow_update' => false, 'uri' => 'http://localhost/bars/1/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['bar' => 'baz', 'operation_name' => 'get', 'resource_class' => 'Foo', 'request_uri' => '/bars/1/foos', 'api_allow_update' => false, 'uri' => 'http://localhost/bars/1/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest($request, false));
 
         $request = Request::create('/foowithpatch/1', 'PATCH');
         $request->attributes->replace(['_api_resource_class' => 'FooWithPatch', '_api_operation_name' => 'patch', '_api_format' => 'json', '_api_mime_type' => 'application/json']);
-        $expected = ['operation_name' => 'patch', 'resource_class' => 'FooWithPatch', 'request_uri' => '/foowithpatch/1', 'api_allow_update' => true, 'uri' => 'http://localhost/foowithpatch/1', 'output' => null, 'input' => null, 'deep_object_to_populate' => true, 'skip_null_values' => true, 'iri_only' => false, 'operation' => $this->patchOperation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['operation_name' => 'patch', 'resource_class' => 'FooWithPatch', 'request_uri' => '/foowithpatch/1', 'api_allow_update' => true, 'uri' => 'http://localhost/foowithpatch/1', 'output' => null, 'input' => null, 'deep_object_to_populate' => true, 'skip_null_values' => true, 'iri_only' => false, 'operation' => $this->patchOperation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest($request, false));
 
         $request = Request::create('/bars/1/foos');
         $request->attributes->replace(['_api_resource_class' => 'Foo', '_api_operation_name' => 'get', '_api_format' => 'xml', '_api_mime_type' => 'text/xml', 'id' => '1']);
-        $expected = ['bar' => 'baz', 'operation_name' => 'get', 'resource_class' => 'Foo', 'request_uri' => '/bars/1/foos', 'api_allow_update' => false, 'uri' => 'http://localhost/bars/1/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'operation' => $this->operation, 'skip_null_values' => true, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['bar' => 'baz', 'operation_name' => 'get', 'resource_class' => 'Foo', 'request_uri' => '/bars/1/foos', 'api_allow_update' => false, 'uri' => 'http://localhost/bars/1/foos', 'output' => null, 'input' => null, 'iri_only' => false, 'operation' => $this->operation, 'skip_null_values' => true, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest($request, false));
     }
 
@@ -115,7 +115,7 @@ public function testThrowExceptionOnInvalidRequest(): void
 
     public function testReuseExistingAttributes(): void
     {
-        $expected = ['bar' => 'baz', 'operation_name' => 'get', 'resource_class' => 'Foo', 'request_uri' => '/foos/1', 'api_allow_update' => false, 'uri' => 'http://localhost/foos/1', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id']];
+        $expected = ['bar' => 'baz', 'operation_name' => 'get', 'resource_class' => 'Foo', 'request_uri' => '/foos/1', 'api_allow_update' => false, 'uri' => 'http://localhost/foos/1', 'output' => null, 'input' => null, 'iri_only' => false, 'skip_null_values' => true, 'operation' => $this->operation, 'exclude_from_cache_key' => ['root_operation', 'operation', 'object', 'data', 'property_metadata', 'circular_reference_limit_counters', 'debug_trace_id'], 'skip_null_to_one_relations' => true];
         $this->assertEquals($expected, $this->builder->createFromRequest(Request::create('/foos/1'), false, ['resource_class' => 'Foo', 'operation_name' => 'get']));
     }
 

tests/Fixtures/TestBundle/ApiResource/Issue4372/RelatedEntity.php

@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\Issue4372;
+
+use ApiPlatform\Metadata\ApiProperty;
+use ApiPlatform\Metadata\ApiResource;
+use ApiPlatform\Metadata\Get;
+use ApiPlatform\Metadata\GetCollection;
+use Symfony\Component\Serializer\Annotation\Groups;
+
+#[ApiResource(
+    operations: [
+        new GetCollection(),
+        new Get(),
+    ]
+)]
+class RelatedEntity
+{
+    #[ApiProperty(identifier: true)]
+    #[Groups(['read'])]
+    public ?int $id = null;
+}

tests/Fixtures/TestBundle/ApiResource/Issue4372/ToOneRelationPropertyMayBeNull.php

@@ -0,0 +1,98 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\Issue4372;
+
+use ApiPlatform\Metadata\ApiProperty;
+use ApiPlatform\Metadata\ApiResource;
+use ApiPlatform\Metadata\Get;
+use ApiPlatform\Metadata\GetCollection;
+use ApiPlatform\Metadata\Operation;
+use ApiPlatform\Serializer\AbstractItemNormalizer;
+use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\Collections\Collection;
+use Symfony\Component\Serializer\Annotation\Groups;
+
+#[ApiResource(
+    operations: [
+        new GetCollection(
+            uriTemplate: self::ROUTE.'{._format}',
+        ),
+        new Get(
+            uriTemplate: self::ITEM_ROUTE.'{._format}',
+            normalizationContext: [
+                AbstractItemNormalizer::SKIP_NULL_TO_ONE_RELATIONS => false,
+                'groups' => ['default', 'read'],
+            ],
+            provider: [self::class, 'provide']
+        ),
+        new Get(
+            uriTemplate: self::ITEM_SKIP_NULL_TO_ONE_RELATION_ROUTE.'{._format}',
+            normalizationContext: [
+                'groups' => ['default', 'read'],
+            ],
+            provider: [self::class, 'provide']
+        ),
+    ],
+)]
+class ToOneRelationPropertyMayBeNull
+{
+    public const ROUTE = '/my-route';
+    public const ITEM_ROUTE = self::ROUTE.'/{id}';
+    public const SKIP_NULL_TO_ONE_RELATION_ROUTE = '/skip-null-relation-route';
+    public const ITEM_SKIP_NULL_TO_ONE_RELATION_ROUTE = self::SKIP_NULL_TO_ONE_RELATION_ROUTE.'/{id}';
+    public const ENTITY_ID = 1;
+
+    #[ApiProperty(identifier: true)]
+    #[Groups(['read'])]
+    public ?int $id = null;
+
+    #[ApiProperty]
+    public ?RelatedEntity $relatedEntity = null;
+
+    #[ApiProperty(readableLink: true)]
+    #[Groups(['read'])]
+    public ?RelatedEntity $relatedEmbeddedEntity = null;
+
+    #[ApiProperty]
+    public ?RelatedEntity $relatedEntity2 = null;
+
+    #[ApiProperty(readableLink: true)]
+    #[Groups(['read'])]
+    public ?RelatedEntity $relatedEmbeddedEntity2 = null;
+
+    #[ApiProperty]
+    #[Groups(['read'])]
+    public Collection $collection;
+
+    public function __construct()
+    {
+        $this->collection = new ArrayCollection();
+    }
+
+    public static function provide(Operation $operation, array $uriVariables = [], array $context = []): ?self
+    {
+        $relatedEntity1 = new RelatedEntity();
+        $relatedEntity1->id = 1;
+        $relatedEntity2 = new RelatedEntity();
+        $relatedEntity2->id = 2;
+
+        $toOneRelationPropertyMayBeNull = new self();
+        $toOneRelationPropertyMayBeNull->id = self::ENTITY_ID;
+        $toOneRelationPropertyMayBeNull->relatedEntity2 = $relatedEntity1;
+        $toOneRelationPropertyMayBeNull->relatedEmbeddedEntity2 = $relatedEntity1;
+        $toOneRelationPropertyMayBeNull->collection = new ArrayCollection([$relatedEntity1, $relatedEntity2]);
+
+        return $toOneRelationPropertyMayBeNull;
+    }
+}