API参考：expressMiddleware

此API参考文档了Apollo Server 4的 Express集成，the expressMiddleware函数。

`expressMiddleware`

ⓘ 注意

以下示例中，我们使用顶层 await 调用来异步启动我们的服务器。如果您想了解如何设置，请查看入门指南以获取详细信息。

函数 expressMiddleware 允许您将 Apollo Server 连接到 Express 服务器。

函数 expressMiddleware 预期您为您的 веб 框架设置 HTTP 请求体解析和 CORS 头部。具体来说，您可以使用 Express 本地的 express.json() 函数（自 Express v4.16.0 开始）和 cors 包来设置您的 Express 应用程序，如下所示。

有关配置项目的 CORS 行为的指导，请参阅配置 CORS。

函数 expressMiddleware 接受两个参数。第一个 必需的 参数是一个 ApolloServer 实例，该实例通过调用其 start 方法已启动：

1
import { ApolloServer } from '@apollo/server';
2
import { expressMiddleware } from '@apollo/server/express4';
3
import cors from 'cors';
4
import express from 'express';
5

6
const app = express();
7

8
const server = new ApolloServer<MyContext>({
9
  typeDefs,
10
  resolvers,
11
});
12
// Note you must call `start()` on the `ApolloServer`
13
// instance before passing the instance to `expressMiddleware`
14
await server.start();
15

16
// Specify the path where we'd like to mount our server
17
app.use('/graphql', cors<cors.CorsRequest>(), express.json(), expressMiddleware(server));

1
import { ApolloServer } from '@apollo/server';
2
import { expressMiddleware } from '@apollo/server/express4';
3
import cors from 'cors';
4
import express from 'express';
5

6
const app = express();
7

8
const server = new ApolloServer({
9
  typeDefs,
10
  resolvers,
11
});
12
// Note you must call `start()` on the `ApolloServer`
13
// instance before passing the instance to `expressMiddleware`
14
await server.start();
15

16
// Specify the path where we'd like to mount our server
17
app.use('/graphql', cors(), express.json(), expressMiddleware(server));
18

⚠️ 为确保您的服务器平稳关闭，我们建议您使用 ApolloServerPluginDrainHttpServer 插件。下面是一个示例。。

该 expressMiddleware 函数的第二个可选对象用于配置 ApolloServer，它可以包含以下选项：

名称 / 类型	描述
`上下文` `函数`	一个可选的异步 `context` 初始化函数。该 `context` 函数应该返回一个对象，该对象在执行一个操作时所有服务器的解析器共享。这允许解析器共享有用的上下文值，例如数据库连接。该 `context` 函数接收 `req` 和 `res` 选项，它们是 `express.Request` 和 `express.Response` 对象。

示例

下面是设置 expressMiddleware 的完整示例：

1
// npm install @apollo/server express graphql cors
2
import { ApolloServer } from '@apollo/server';
3
import { expressMiddleware } from '@apollo/server/express4';
4
import { ApolloServerPluginDrainHttpServer } from '@apollo/server/plugin/drainHttpServer';
5
import express from 'express';
6
import http from 'http';
7
import cors from 'cors';
8
import { typeDefs, resolvers } from './schema';
9

10
interface MyContext {
11
  token?: string;
12
}
13

14
// Required logic for integrating with Express
15
const app = express();
16
// Our httpServer handles incoming requests to our Express app.
17
// Below, we tell Apollo Server to "drain" this httpServer,
18
// enabling our servers to shut down gracefully.
19
const httpServer = http.createServer(app);
20

21
// Same ApolloServer initialization as before, plus the drain plugin
22
// for our httpServer.
23
const server = new ApolloServer<MyContext>({
24
  typeDefs,
25
  resolvers,
26
  plugins: [ApolloServerPluginDrainHttpServer({ httpServer })],
27
});
28
// Ensure we wait for our server to start
29
await server.start();
30

31
// Set up our Express middleware to handle CORS, body parsing,
32
// and our expressMiddleware function.
33
app.use(
34
  '/',
35
  cors<cors.CorsRequest>(),
36
  express.json(),
37
  // expressMiddleware accepts the same arguments:
38
  // an Apollo Server instance and optional configuration options
39
  expressMiddleware(server, {
40
    context: async ({ req }) => ({ token: req.headers.token }),
41
  }),
42
);
43

44
// Modified server startup
45
await new Promise<void>((resolve) => httpServer.listen({ port: 4000 }, resolve));
46
console.log(`🚀 Server ready at https://127.0.0.1:4000/`);

1
// npm install @apollo/server express graphql cors
2
import { ApolloServer } from '@apollo/server';
3
import { expressMiddleware } from '@apollo/server/express4';
4
import { ApolloServerPluginDrainHttpServer } from '@apollo/server/plugin/drainHttpServer';
5
import express from 'express';
6
import http from 'http';
7
import cors from 'cors';
8
import { typeDefs, resolvers } from './schema';
9

10
// Required logic for integrating with Express
11
const app = express();
12
// Our httpServer handles incoming requests to our Express app.
13
// Below, we tell Apollo Server to "drain" this httpServer,
14
// enabling our servers to shut down gracefully.
15
const httpServer = http.createServer(app);
16

17
// Same ApolloServer initialization as before, plus the drain plugin
18
// for our httpServer.
19
const server = new ApolloServer({
20
  typeDefs,
21
  resolvers,
22
  plugins: [ApolloServerPluginDrainHttpServer({ httpServer })],
23
});
24
// Ensure we wait for our server to start
25
await server.start();
26

27
// Set up our Express middleware to handle CORS, body parsing,
28
// and our expressMiddleware function.
29
app.use(
30
  '/',
31
  cors(),
32
  express.json(),
33
  // expressMiddleware accepts the same arguments:
34
  // an Apollo Server instance and optional configuration options
35
  expressMiddleware(server, {
36
    context: async ({ req }) => ({ token: req.headers.token }),
37
  }),
38
);
39

40
// Modified server startup
41
await new Promise((resolve) => httpServer.listen({ port: 4000 }, resolve));
42

43
console.log(`🚀 Server ready at https://127.0.0.1:4000/`);

startStandaloneServer

概述

API参考：expressMiddleware

expressMiddleware

上下文

示例

`expressMiddleware`

`上下文`