Support adding custom parameters

src/Lti/Lti11/Context/DeepLinkingProps.php

@@ -6,6 +6,7 @@
 
 use Cerpus\EdlibResourceKit\Lti\Message\DeepLinking\PresentationDocumentTarget;
 use DateTimeImmutable;
+
 use function array_filter;
 use function array_map;
 use function preg_replace;
@@ -15,6 +16,7 @@ final class DeepLinkingProps
     public const JSONLD_VOCAB = 'http://purl.imsglobal.org/ctx/lti/v1/ContentItem';
 
     public const COPY_ADVICE = 'copyAdvice';
+    public const CUSTOM = 'custom';
     public const EXPIRES_AT = 'expiresAt';
     public const DISPLAY_HEIGHT = 'displayHeight';
     public const DISPLAY_WIDTH = 'displayWidth';
@@ -41,6 +43,7 @@ final class DeepLinkingProps
     public const TYPE_FLOAT = 'http://www.w3.org/2001/XMLSchema#float';
     public const TYPE_INTEGER = 'http://www.w3.org/2001/XMLSchema#integer';
     public const TYPE_NORMALIZED_STRING = 'http://www.w3.org/2001/XMLSchema#normalizedString';
+    public const TYPE_STRING = 'http://www.w3.org/2001/XMLSchema#string';
 
     public static function getCopyAdvice(array $data): bool|null
     {
@@ -116,6 +119,13 @@ public static function getWindowTarget(array $data): string|null
         return self::getOfType($data, self::WINDOW_TARGET, self::TYPE_NORMALIZED_STRING);
     }
 
+    public static function getCustom(array $data): array|null
+    {
+        $custom = self::getArrayOfType($data, self::CUSTOM, self::TYPE_STRING);
+
+        return empty($custom) ? null : $custom;
+    }
+
     public static function getOfType(array $data, string $prop, string $type): mixed
     {
         $value = $data[$prop] ?? null;

src/Lti/Lti11/Mapper/DeepLinking/ContentItemMapper.php

@@ -42,8 +42,8 @@ public function map(array $data): ContentItem
                 $thumbnail,
                 Prop::getTitle($data),
                 Prop::getUrl($data),
-                custom: [], // TODO
-                lineItem: $lineItem,
+                Prop::getCustom($data),
+                $lineItem,
             );
         }
 

src/Lti/Lti11/Serializer/DeepLinking/LtiLinkItemSerializer.php

@@ -10,14 +10,11 @@
 final readonly class LtiLinkItemSerializer implements LtiLinkItemSerializerInterface
 {
     public function __construct(
-        private ContentItemSerializer $serializer = new ContentItemSerializer(),
+        private ContentItemSerializerInterface $serializer = new ContentItemSerializer(),
         private LineItemSerializerInterface $lineItemSerializer = new LineItemSerializer(),
     ) {
     }
 
-    /**
-     * @todo Handle the "custom" property
-     */
     public function serialize(LtiLinkItem $item): array
     {
         $serialized = [
@@ -31,6 +28,10 @@ public function serialize(LtiLinkItem $item): array
                 ->serialize($item->getLineItem());
         }
 
+        if (!empty($item->getCustom())) {
+            $serialized[Prop::CUSTOM] = $item->getCustom();
+        }
+
         return $serialized;
     }
 }

src/Lti/Message/DeepLinking/LtiLinkItem.php

@@ -17,7 +17,7 @@ public function __construct(
         Image|null $thumbnail = null,
         string|null $title = null,
         string|null $url = null,
-        private readonly array $custom = [],
+        private readonly array|null $custom = null,
         private readonly LineItem|null $lineItem = null,
     ) {
         parent::__construct(
@@ -31,7 +31,7 @@ public function __construct(
         );
     }
 
-    public function getCustom(): array
+    public function getCustom(): array|null
     {
         return $this->custom;
     }

tests/Lti/Lti11/Mapper/ContentItemsMapperTest.php

@@ -60,6 +60,10 @@ public function testItMapsAllTheStuff(): void
                             'totalMaximum' => 42.0,
                         ],
                     ],
+                    'custom' => [
+                        'level' => 'expert',
+                        'numericLevel' => 42,
+                    ],
                 ],
                 [
                     '@type' => 'FileItem',
@@ -105,6 +109,11 @@ public function testItMapsAllTheStuff(): void
         $this->assertSame(39.5, $score->getNormalMaximum());
         $this->assertSame(2.5, $score->getExtraCreditMaximum());
         $this->assertSame(42.0, $score->getTotalMaximum());
+
+        $custom = $contentItems[0]->getCustom();
+        $this->assertIsArray($custom);
+        $this->assertSame('expert', $custom['level']);
+        $this->assertSame(42, $custom['numericLevel']);
     }
 
     public function testMapsDataWithAdditionalJsonldContexts(): void

tests/Lti/Lti11/Serializer/ContentItemsSerializerTest.php

@@ -70,6 +70,10 @@ public function testSerializesContentItems(): array
                 text: 'A cool text description of my cool content',
                 title: 'My Cool Content',
                 url: 'https://example.com/lti',
+                custom: [
+                    'level' => 'expert',
+                    'numericLevel' => 42,
+                ],
                 lineItem: new LineItem(
                     new ScoreConstraints(39.5, 2.5)
                 ),
@@ -118,6 +122,10 @@ public function testSerializesContentItems(): array
                             'totalMaximum' => 42.0,
                         ],
                     ],
+                    'custom' => [
+                        'level' => 'expert',
+                        'numericLevel' => 42,
+                    ],
                 ],
                 [
                     '@type' => 'FileItem',