GQL: Handle invalid Item ID and Item not found

Bug: T400473
Change-Id: Iaafd19eb5cc067326862cd3cc0eef4e1ec657e60

Author: jakobw

repo/includes/GraphQLPrototype/InvalidItemId.php

@@ -0,0 +1,14 @@
+<?php declare( strict_types=1 );
+
+namespace Wikibase\Repo\GraphQLPrototype;
+
+use GraphQL\Error\ClientAware;
+
+/**
+ * @license GPL-2.0-or-later
+ */
+class InvalidItemId extends \Exception implements ClientAware {
+	public function isClientSafe(): bool {
+		return true;
+	}
+}

repo/includes/GraphQLPrototype/ItemNotFound.php

@@ -0,0 +1,14 @@
+<?php declare( strict_types=1 );
+
+namespace Wikibase\Repo\GraphQLPrototype;
+
+use GraphQL\Error\ClientAware;
+
+/**
+ * @license GPL-2.0-or-later
+ */
+class ItemNotFound extends \Exception implements ClientAware {
+	public function isClientSafe(): bool {
+		return true;
+	}
+}

repo/includes/GraphQLPrototype/ItemResolver.php

@@ -0,0 +1,33 @@
+<?php declare( strict_types=1 );
+
+namespace Wikibase\Repo\GraphQLPrototype;
+
+use InvalidArgumentException;
+use Wikibase\DataModel\Entity\ItemId;
+use Wikibase\DataModel\Services\Lookup\EntityLookup;
+
+/**
+ * @license GPL-2.0-or-later
+ */
+class ItemResolver {
+	public function __construct( private EntityLookup $entityLookup ) {
+	}
+
+	/**
+	 * @throws InvalidItemId
+	 * @throws ItemNotFound
+	 */
+	public function fetchItem( string $itemId ): array {
+		try {
+			$parsedId = new ItemId( $itemId );
+		} catch ( InvalidArgumentException ) {
+			throw new InvalidItemId( "Invalid Item ID: '$itemId'." );
+		}
+
+		if ( !$this->entityLookup->hasEntity( $parsedId ) ) {
+			throw new ItemNotFound( "Item '$parsedId' does not exist." );
+		}
+
+		return [ 'id' => $parsedId->getSerialization() ];
+	}
+}

repo/includes/GraphQLPrototype/Schema.php

@@ -19,6 +19,7 @@ public function __construct(
 		private ContentLanguages $labelLanguages,
 		private LabelsResolver $labelsResolver,
 		private StatementsResolver $statementsResolver,
+		private ItemResolver $itemResolver,
 	) {
 		parent::__construct( [
 			'query' => new ObjectType( [
@@ -29,7 +30,7 @@ public function __construct(
 						'args' => [
 							'id' => Type::nonNull( Type::string() ),
 						],
-						'resolve' => fn( $rootValue, array $args ) => [ 'id' => $args['id'] ],
+						'resolve' => fn( $rootValue, array $args ) => $this->itemResolver->fetchItem( $args['id'] ),
 					],
 				],
 			] ),

repo/includes/GraphQLPrototype/SpecialWikibaseGraphQL.php

@@ -25,6 +25,7 @@ public function __construct(
 			$termLanguages,
 			new LabelsResolver( $termLookup ),
 			new StatementsResolver( $entityLookup ),
+			new ItemResolver( $entityLookup )
 		) );
 	}
 

repo/tests/phpunit/includes/GraphQLPrototype/GraphQLQueryServiceTest.php

@@ -13,6 +13,7 @@
 use Wikibase\DataModel\Tests\NewItem;
 use Wikibase\DataModel\Tests\NewStatement;
 use Wikibase\Repo\GraphQLPrototype\GraphQLQueryService;
+use Wikibase\Repo\GraphQLPrototype\ItemResolver;
 use Wikibase\Repo\GraphQLPrototype\LabelsResolver;
 use Wikibase\Repo\GraphQLPrototype\Schema;
 use Wikibase\Repo\GraphQLPrototype\StatementsResolver;
@@ -122,11 +123,30 @@ public function testStatementsQueryWithPropertyLabels(): void {
 		);
 	}
 
+	public function testInvalidItemId(): void {
+		$result = $this->newGraphQLService()->query( 'query { item(id: "X123") { id } }' );
+		$this->assertSame(
+			"Invalid Item ID: 'X123'.",
+			$result['errors'][0]['message']
+		);
+	}
+
+	public function testItemNotFound(): void {
+		$result = $this->newGraphQLService()->query( 'query { item(id: "Q999999") { id } }' );
+		$this->assertSame(
+			"Item 'Q999999' does not exist.",
+			$result['errors'][0]['message']
+		);
+	}
+
 	public function newGraphQLService(): GraphQLQueryService {
+		$entityLookup = WikibaseRepo::getEntityLookup();
+
 		return new GraphQLQueryService( new Schema(
 			WikibaseRepo::getTermsLanguages(),
 			new LabelsResolver( WikibaseRepo::getPrefetchingTermLookup() ),
-			new StatementsResolver( WikibaseRepo::getEntityLookup() )
+			new StatementsResolver( $entityLookup ),
+			new ItemResolver( $entityLookup ),
 		) );
 	}