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如何与 `express-session` 一起使用

让我们从一个基本应用程序开始

const express = require("express");
const { createServer } = require("node:http");
const { join } = require("node:path");
const { Server } = require("socket.io");
const session = require("express-session");

const port = process.env.PORT || 3000;

const app = express();
const httpServer = createServer(app);

const sessionMiddleware = session({
  secret: "changeit",
  resave: true,
  saveUninitialized: true,
});

app.use(sessionMiddleware);

app.get("/", (req, res) => {
  res.sendFile(join(__dirname, "index.html"));
});

app.post("/incr", (req, res) => {
  const session = req.session;
  session.count = (session.count || 0) + 1;
  res.status(200).end("" + session.count);
});

const io = new Server(httpServer);

httpServer.listen(port, () => {
  console.log(`application is running at: http://localhost:${port}`);
});

共享会话上下文​

可以通过调用来与 Socket.IO 服务器共享会话上下文

io.engine.use(sessionMiddleware);

就这么简单！您现在可以访问 `session` 对象

io.on("connection", (socket) => {
  const session = socket.request.session;
});

使用会话 ID​

您可以使用会话 ID 来建立 Express 和 Socket.IO 之间的链接

io.on("connection", (socket) => {
  const sessionId = socket.request.session.id;

  // the session ID is used as a room
  socket.join(sessionId);
});

然后，您可以在 `/incr` 处理程序中通知每个连接的客户端

app.post("/incr", (req, res) => {
  const session = req.session;
  session.count = (session.count || 0) + 1;
  res.status(200).end("" + session.count);

  io.to(session.id).emit("current count", session.count);
});

注销流程也是如此

app.post("/logout", (req, res) => {
  const sessionId = req.session.id;

  req.session.destroy(() => {
    // disconnect all Socket.IO connections linked to this session ID
    io.in(sessionId).disconnectSockets();
    res.status(204).end();
  });
});

修改会话​

由于它不绑定到单个 HTTP 请求，因此必须手动重新加载和保存会话

io.on("connection", (socket) => {
  const req = socket.request;

  socket.on("my event", () => {
    req.session.reload((err) => {
      if (err) {
        return socket.disconnect();
      }
      req.session.count++;
      req.session.save();
    });
  });
});

您也可以使用 中间件，它将在每个传入数据包触发

io.on("connection", (socket) => {
  const req = socket.request;

  socket.use((__, next) => {
    req.session.reload((err) => {
      if (err) {
        socket.disconnect();
      } else {
        next();
      }
    });
  });

  // and then simply
  socket.on("my event", () => {
    req.session.count++;
    req.session.save();
  });
});
注意

调用 `req.session.reload()` 会更新 `req.session` 对象

io.on("connection", (socket) => {
  const session = socket.request.session;

  socket.use((__, next) => {
    session.reload(() => {
      // WARNING! "session" still points towards the previous session object
    });
  });
});

处理会话过期​

您可能还想定期重新加载会话，以防会话过期（例如，如果客户端在较长时间内未发送任何事件）

const SESSION_RELOAD_INTERVAL = 30 * 1000;

io.on("connection", (socket) => {
  const timer = setInterval(() => {
    socket.request.session.reload((err) => {
      if (err) {
        // forces the client to reconnect
        socket.conn.close();
        // you can also use socket.disconnect(), but in that case the client
        // will not try to reconnect
      }
    });
  }, SESSION_RELOAD_INTERVAL);

  socket.on("disconnect", () => {
    clearInterval(timer);
  });
});

跨站点请求的说明​

express-session 依赖于 cookie 在浏览器中持久保存会话。因此，如果您的前端域与您的后端域不同（例如，如果您在您的机器上运行 SPA，但在不同的端口上），那么您需要发送适当的 CORS 标头

const cors = require("cors");
    
const corsOptions = {
  origin: ["http://localhost:4200"],
  credentials: true
};

// for Express
app.use(cors(corsOptions));

// for Socket.IO
const io = new Server(httpServer, {
  cors: corsOptions
});

您还需要在客户端设置 `withCredentials` 选项为 `true`

import { io } from "socket.io-client";

const socket = io("http://localhost:3000", {
  withCredentials: true
});

这就是与 `express-session` 的兼容性。感谢您的阅读！

提示

您可以在浏览器中直接运行此示例