API Platform GraphQL Symfony: Schema, Mutation และคำถามสัมภาษณ์ 2026

# Install GraphQL support
composer require api-platform/graphql

namespace App\Entity;

use ApiPlatform\Metadata\ApiResource;
use ApiPlatform\Metadata\GraphQl\Query;
use ApiPlatform\Metadata\GraphQl\QueryCollection;
use ApiPlatform\Metadata\GraphQl\Mutation;
use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity]
#[ApiResource(
    graphQlOperations: [
        new Query(),
        new QueryCollection(),
        new Mutation(name: 'create'),
        new Mutation(name: 'update'),
        new Mutation(name: 'delete'),
    ]
)]
class Book
{
    #[ORM\Id]
    #[ORM\GeneratedValue]
    #[ORM\Column]
    private ?int $id = null;

    #[ORM\Column(length: 255)]
    private string $title;

    #[ORM\Column(length: 13)]
    private string $isbn;

    #[ORM\Column]
    private \DateTimeImmutable $publishedAt;

    // Getters and setters...
}

# Fetch a single book with specific fields
query GetBook {
  book(id: "/books/42") {
    title
    isbn
    publishedAt
  }
}

# Fetch a collection with pagination
query ListBooks {
  books(first: 10, after: "cursor123") {
    edges {
      node {
        id
        title
      }
      cursor
    }
    pageInfo {
      hasNextPage
      endCursor
    }
  }
}

# Create a new book
mutation CreateBook {
  createBook(input: {
    title: "Domain-Driven Design"
    isbn: "9780321125217"
    publishedAt: "2003-08-30"
    clientMutationId: "create-1"
  }) {
    book {
      id
      title
    }
    clientMutationId
  }
}

# Update an existing book
mutation UpdateBook {
  updateBook(input: {
    id: "/books/42"
    title: "Updated Title"
    clientMutationId: "update-1"
  }) {
    book {
      id
      title
    }
  }
}

namespace App\Resolver;

use ApiPlatform\GraphQl\Resolver\QueryCollectionResolverInterface;
use App\Repository\BookRepository;

final class BookBestSellerResolver implements QueryCollectionResolverInterface
{
    public function __construct(
        private readonly BookRepository $bookRepository
    ) {}

    /**
     * @param iterable<Book> $collection
     * @return iterable<Book>
     */
    public function __invoke(iterable $collection, array $context): iterable
    {
        // Access GraphQL arguments from context
        $limit = $context['args']['limit'] ?? 10;
        $period = $context['args']['period'] ?? 'month';

        return $this->bookRepository->findBestSellers($limit, $period);
    }
}

#[ApiResource(
    graphQlOperations: [
        new QueryCollection(
            name: 'bestSellers',
            resolver: BookBestSellerResolver::class,
            args: [
                'limit' => ['type' => 'Int', 'default_value' => 10],
                'period' => ['type' => 'String', 'default_value' => 'month'],
            ]
        ),
    ]
)]
class Book
{
    // ...
}

use ApiPlatform\Metadata\GraphQl\Query;
use ApiPlatform\Metadata\GraphQl\Mutation;

#[ApiResource(
    graphQlOperations: [
        new Query(
            security: "is_granted('ROLE_USER')"
        ),
        new QueryCollection(
            security: "is_granted('ROLE_USER')"
        ),
        new Mutation(
            name: 'create',
            security: "is_granted('ROLE_EDITOR')"
        ),
        new Mutation(
            name: 'update',
            security: "is_granted('ROLE_EDITOR') and object.getAuthor() == user",
            securityMessage: "Only the author can update this book."
        ),
        new Mutation(
            name: 'delete',
            security: "is_granted('ROLE_ADMIN')"
        ),
    ]
)]
class Book
{
    // ...
}

namespace App\Security\Voter;

use App\Entity\Book;
use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
use Symfony\Component\Security\Core\Authorization\Voter\Voter;
use Symfony\Component\Security\Core\User\UserInterface;

class BookVoter extends Voter
{
    public const EDIT = 'BOOK_EDIT';
    public const DELETE = 'BOOK_DELETE';

    protected function supports(string $attribute, mixed $subject): bool
    {
        return in_array($attribute, [self::EDIT, self::DELETE])
            && $subject instanceof Book;
    }

    protected function voteOnAttribute(
        string $attribute,
        mixed $subject,
        TokenInterface $token
    ): bool {
        $user = $token->getUser();
        if (!$user instanceof UserInterface) {
            return false;
        }

        /** @var Book $book */
        $book = $subject;

        return match($attribute) {
            self::EDIT => $book->getAuthor() === $user,
            self::DELETE => in_array('ROLE_ADMIN', $user->getRoles()),
            default => false,
        };
    }
}

use ApiPlatform\Metadata\GraphQl\Subscription;

#[ApiResource(
    mercure: true,
    graphQlOperations: [
        new Query(),
        new Mutation(name: 'update'),
        new Subscription(),
    ]
)]
class Book
{
    // ...
}

subscription BookUpdates {
  updateBookSubscribe(input: { id: "/books/42" }) {
    book {
      id
      title
      updatedAt
    }
  }
}

// Custom query extension for eager loading
public function applyToCollection(
    QueryBuilder $queryBuilder,
    QueryNameGeneratorInterface $queryNameGenerator,
    string $resourceClass,
    ?Operation $operation = null,
    array $context = []
): void {
    $queryBuilder
        ->addSelect('author')
        ->leftJoin('o.author', 'author');
}

# config/packages/api_platform.yaml
api_platform:
    graphql:
        enabled: true
        graphiql:
            enabled: true

namespace App\GraphQL\Type;

use GraphQL\Type\Definition\ScalarType;

final class DateTimeType extends ScalarType
{
    public string $name = 'DateTime';

    public function serialize($value): string
    {
        return $value->format(\DateTimeInterface::RFC3339);
    }

    public function parseValue($value): \DateTimeImmutable
    {
        return new \DateTimeImmutable($value);
    }

    public function parseLiteral($valueNode, ?array $variables = null): \DateTimeImmutable
    {
        return new \DateTimeImmutable($valueNode->value);
    }
}

# Cursor-based (default)
query {
  books(first: 10, after: "YXJyYXljb25uZWN0aW9uOjk=") {
    edges {
      cursor
      node {
        title
      }
    }
    pageInfo {
      endCursor
      hasNextPage
    }
  }
}

// Enable page-based pagination
#[ApiResource(
    paginationType: 'page',
    graphQlOperations: [
        new QueryCollection(paginationType: 'page'),
    ]
)]
class Book {}

# Page-based
query {
  books(page: 2, itemsPerPage: 20) {
    collection {
      title
    }
    paginationInfo {
      totalCount
      lastPage
    }
  }
}

namespace App\Tests\GraphQL;

use ApiPlatform\Symfony\Bundle\Test\ApiTestCase;
use App\Entity\Book;

class BookTest extends ApiTestCase
{
    public function testQueryBook(): void
    {
        $client = static::createClient();

        // Create test data
        $book = new Book();
        $book->setTitle('Test Book');
        $book->setIsbn('1234567890123');
        $book->setPublishedAt(new \DateTimeImmutable());

        $em = static::getContainer()->get('doctrine')->getManager();
        $em->persist($book);
        $em->flush();

        // Execute GraphQL query
        $response = $client->request('POST', '/graphql', [
            'json' => [
                'query' => '
                    query GetBook($id: ID!) {
                        book(id: $id) {
                            title
                            isbn
                        }
                    }
                ',
                'variables' => [
                    'id' => '/books/' . $book->getId(),
                ],
            ],
        ]);

        $this->assertResponseIsSuccessful();
        $data = $response->toArray();

        $this->assertEquals('Test Book', $data['data']['book']['title']);
        $this->assertEquals('1234567890123', $data['data']['book']['isbn']);
    }

    public function testMutationRequiresAuthentication(): void
    {
        $client = static::createClient();

        $response = $client->request('POST', '/graphql', [
            'json' => [
                'query' => '
                    mutation CreateBook {
                        createBook(input: {
                            title: "Unauthorized Book"
                            isbn: "0000000000000"
                            clientMutationId: "test"
                        }) {
                            book { id }
                        }
                    }
                ',
            ],
        ]);

        $data = $response->toArray();
        $this->assertArrayHasKey('errors', $data);
    }
}