Symfony与GraphQL分页查询

在Symfony中结合GraphQL实现分页查询，你可以使用一些流行的库，如graphql-bundle和knp-paginator-bundle。下面是一个简单的示例，展示如何在Symfony中使用GraphQL进行分页查询。

首先，确保你已经安装了graphql-bundle和knp-paginator-bundle。你可以通过Composer来安装它们：

composer require friendsofsymfony/graphql-bundle knp/paginator-bundle

接下来，配置这些包。在config/packages/graphql.yaml中配置GraphQL：

framework:
    graphql:
        enabled: true
        schema_path: src/GraphQL/Schema/schema.graphql
        resolvers:
            App\GraphQL\Resolver\QueryResolver: ~

在config/packages/knp_paginator.yaml中配置分页：

knp_paginator:
    page_size: 10
    default_page_number: 1

现在，创建一个GraphQL schema文件src/GraphQL/Schema/schema.graphql，定义你的查询和分页类型：

type Query {
    items(page: Int = 1, pageSize: Int = 10): ItemsConnection!
}

type ItemsConnection {
    totalCount: Int!
    pageInfo: PageInfo!
    edges: [ItemEdge!]!
}

type ItemEdge {
    node: Item!
    cursor: String!
}

type Item {
    id: ID!
    name: String!
}

type PageInfo {
    hasNextPage: Boolean!
    hasPreviousPage: Boolean!
    startCursor: String
    endCursor: String
}

接下来，创建一个解析器src/GraphQL/Resolver/QueryResolver.php，实现分页查询：

namespace App\GraphQL\Resolver;

use App\Entity\Item;
use GraphQL\Error\Error;
use GraphQL\Object\Source;
use GraphQL\Type\Definition\ResolveInfo;
use GraphQL\Type\Definition\Type;
use Knp\Component\Pager\PaginatorInterface;
use Symfony\Component\HttpFoundation\RequestStack;

class QueryResolver
{
    private $paginator;
    private $requestStack;

    public function __construct(PaginatorInterface $paginator, RequestStack $requestStack)
    {
        $this->paginator = $paginator;
        $this->requestStack = $requestStack;
    }

    public function items(int $page = 1, int $pageSize = 10): ItemsConnection
    {
        $request = $this->requestStack->getCurrentRequest();
        $queryParams = $request->query->all();

        $items = $this->paginator->paginate(
            Item::class,
            $queryParams['page'] ?? $page,
            $queryParams['pageSize'] ?? $pageSize,
            ['defaultSort' => ['id' => 'ASC']]
        );

        return new ItemsConnection(
            $items->getTotalCount(),
            new PageInfo($items->hasNextPage(), $items->hasPreviousPage(), $items->startCursor(), $items->endCursor()),
            $this->createEdges($items)
        );
    }

    private function createEdges(iterable $items): array
    {
        $edges = [];

        foreach ($items as $item) {
            $edges[] = new ItemEdge(
                $item,
                $item->getId()
            );
        }

        return $edges;
    }
}

最后，确保你的Item实体已经正确设置，并且你已经配置了GraphQL和分页组件。现在，你可以通过GraphQL查询进行分页：

query {
  items(page: 1, pageSize: 5) {
    totalCount
    pageInfo {
      hasNextPage
      hasPreviousPage
      startCursor
      endCursor
    }
    edges {
      node {
        id
        name
      }
      cursor
    }
  }
}

这个示例展示了如何在Symfony中使用GraphQL实现分页查询。你可以根据自己的需求进行调整和扩展。