从零开始构建 PHP GraphQL 后端：一步一步教你-编程学习网

1. 前提条件

在开始构建 PHP GraphQL 后端之前，您需要确保已经满足以下前提条件：

- PHP 7.2+
- Composer
- GraphQL PHP 库

2. 初始化项目

首先，使用 Composer 创建一个新的 PHP 项目。

composer create-project --prefer-dist laravel/laravel your-project-name

接下来，安装 GraphQL PHP 库。

composer require graphql/graphql:^0.14

3. 创建 GraphQL Schema

GraphQL Schema 定义了您的 API 的结构，包括数据类型、查询和突变。在 app/GraphQL/Types 目录下创建一个新的文件 UserType.php，内容如下：

namespace AppGraphQLTypes;

use GraphQLTypeDefinitionType;
use GraphQLTypeDefinitionObjectType;

class UserType extends ObjectType
{
    public function __construct()
    {
        $config = [
            "name" => "User",
            "description" => "A user",
            "fields" => [
                "id" => [
                    "type" => Type::string(),
                    "description" => "The ID of the user"
                ],
                "name" => [
                    "type" => Type::string(),
                    "description" => "The name of the user"
                ],
                "email" => [
                    "type" => Type::string(),
                    "description" => "The email of the user"
                ],
            ]
        ];

        parent::__construct($config);
    }
}

同样的方法，分别在 app/GraphQL/Types 目录下创建 QueryType.php 和 MutationType.php 文件，定义查询和突变类型。

4. 定义查询和突变解析器

接下来，需要定义查询和突变解析器，这些解析器将处理 GraphQL 请求并返回数据。在 app/GraphQL/Resolvers 目录下创建文件 UserResolver.php，内容如下：

namespace AppGraphQLResolvers;

use AppUser;
use GraphQLTypeDefinitionResolveInfo;

class UserResolver
{
    /**
     * 获取所有用户
     *
     * @param mixed $rootValue
     * @param array $args
     * @param mixed $context
     * @param ResolveInfo $info
     * @return mixed
     */
    public function all($rootValue, array $args, $context, ResolveInfo $info)
    {
        return User::all();
    }

    /**
     * 获取单个用户
     *
     * @param mixed $rootValue
     * @param array $args
     * @param mixed $context
     * @param ResolveInfo $info
     * @return mixed
     */
    public function find($rootValue, array $args, $context, ResolveInfo $info)
    {
        return User::find($args["id"]);
    }

    /**
     * 创建一个用户
     *
     * @param mixed $rootValue
     * @param array $args
     * @param mixed $context
     * @param ResolveInfo $info
     * @return mixed
     */
    public function create($rootValue, array $args, $context, ResolveInfo $info)
    {
        $user = new User();
        $user->name = $args["name"];
        $user->email = $args["email"];
        $user->save();

        return $user;
    }

    /**
     * 更新一个用户
     *
     * @param mixed $rootValue
     * @param array $args
     * @param mixed $context
     * @param ResolveInfo $info
     * @return mixed
     */
    public function update($rootValue, array $args, $context, ResolveInfo $info)
    {
        $user = User::find($args["id"]);
        $user->name = $args["name"];
        $user->email = $args["email"];
        $user->save();

        return $user;
    }

    /**
     * 删除一个用户
     *
     * @param mixed $rootValue
     * @param array $args
     * @param mixed $context
     * @param ResolveInfo $info
     * @return mixed
     */
    public function delete($rootValue, array $args, $context, ResolveInfo $info)
    {
        $user = User::find($args["id"]);
        $user->delete();

        return $user;
    }
}

5. 创建 GraphQL 服务提供者

创建一个 GraphQL 服务提供者 app/Providers/GraphQLServiceProvider.php，内容如下：

namespace AppProviders;

use IlluminateSupportServiceProvider;
use GraphQLTypeSchema;
use GraphQLServerServerConfig;
use GraphQLServerStandardServer;
use NuwaveLighthouseSchemaTypeRegistry;
use NuwaveLighthouseGraphQL;

class GraphQLServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap the application services.
     *
     * @return void
     */
    public function boot()
    {
        $this->app->singleton(
            Schema::class,
            function () {
                $schema = new Schema([
                    "query" => TypeRegistry::get(GraphQL::TYPE_QUERY),
                    "mutation" => TypeRegistry::get(GraphQL::TYPE_MUTATION)
                ]);

                return $schema;
            }
        );

        $this->app->singleton(
            StandardServer::class,
            function () {
                $config = ServerConfig::create();

                return new StandardServer($config);
            }
        );
    }

    /**
     * Register the application services.
     *
     * @return void
     */
    public function register()
    {
        $this->app->make(GraphQL::class);
    }
}

6. 注册 GraphQL 服务提供者

在 config/app.php 文件中注册 GraphQL 服务提供者：

"providers" => [
    // Other providers

    AppProvidersGraphQLServiceProvider::class,
]

7. 设置 GraphQL 路由

在 routes/api.php 文件中设置 GraphQL 路由：

use GraphQLServerStandardServer;

Route::post("/graphql", function (StandardServer $server) {
    return $server->process();
});

8. 启动 GraphQL 服务

在 public/index.php 文件中启动 GraphQL 服务：

define("LARAVEL_START", microtime(true));

require __DIR__."/../bootstrap/autoload.php";

$app = require_once __DIR__."/../bootstrap/app.php";

$server = $app->make(StandardServer::class);

$server->process();