如何在单独的文件 Express.js 应用程序中定义 app.js 之外的所有 socket.io 逻辑？

Question

期望的行为

socket.io initialisation docs 提供了这个示例，我目前在app.js 中使用：

import { createServer } from "http";
import { Server } from "socket.io";

const httpServer = createServer();
const io = new Server(httpServer, {
  // ...
});

io.on("connection", (socket) => {
  // ...
});

httpServer.listen(3000);

io 块之前还有三个对象需要在块内引用：

var logged_in_users = {};
var users_in_rooms = {};
var live_edits_occurring = {}; 

如您所见，一切都发生在app.js。

我想重构 app.js 以便：

1. io.on('connection') 功能块中的所有逻辑都在app.js 之外
2. 可以在中间件文件中访问全局对象（logged_in_users 等）

实际行为

我收到此错误：

ReferenceError:logged_in_users 未定义

这意味着我无法从中间件文件访问logged_in_users。

问题

我怎样才能让像logged_in_users 这样的对象可以全局访问？

以便它们可以被所有中间件文件引用和更新？

app.locals 会是一个好方法吗？

// app.js  
app.locals.logged_in_users = {};
app.locals.users_in_rooms = {};
app.locals.live_edits_occurring = {}; 

我之前没有使用过app.locals，也不知道如何在中间件中访问app。

我也不知道你是否可以从中间件更新app.locals，我需要这样做。

我的尝试

关注the docs on application structure，我有：

app.js

const express = require('express');
const { createServer } = require('http');
const { Server } = require('socket.io');
const app = express();
const httpServer = createServer(app);
const io = new Server(httpServer);


const all_socketio_logic = require('./middleware/socketio/all_socketio_logic').all_socketio_logic;    
  
const on_connection = async (socket) => {
  all_socketio_logic(io, socket);
};

io.on('connection', on_connection);

/middleware/socketio/all_socketio_logic.js

import { heres_my_details } from './event_handler_heres_my_details';

const all_socketio_logic = (io, socket) => {

  // i want these available in the middleware defined below     
  var logged_in_users = {};
  var users_in_rooms = {};
  var live_edits_occurring = {};

  // sanity checks - all returning values - GOOD   
  console.log('socket.id is: ' + socket.id);
  console.log('logged_in_users is: ');
  console.log(logged_in_users);
  console.log('users_in_rooms is: ');
  console.log(users_in_rooms);
  console.log('live_edits_occurring is: ');
  console.log(live_edits_occurring);

  // this is being returned to browser - GOOD 
  socket.emit('heres_your_socket_id', socket.id);  

  // this middleware is running - GOOD  
  socket.on('heres_my_details', heres_my_details);

  /*

  i will add other event handlers here:  
  
  socket.on('another_event_01', another_event_01);
  socket.on('another_event_02', another_event_02);

  etc  

  */

};

export { all_socketio_logic };

/middleware/socketio/event_handler_heres_my_details.js

const heres_my_details = (data) => {
  
  console.log('heres_my_details:');
  console.log(data);
  
  var username = data.username;
  
  // if client is logged in
  if (username !== null) {
    var user_email = data.user_email;
  
    /* 
      if the logged_in_users object doesn't already contain 
      the clients socket id (as a property), add the socket 
      id property and define object username and user_email 
    */
  
    if (!logged_in_users.hasOwnProperty(socket.id)) {
      // the error is here - cannot access logged_in_users  
      logged_in_users[socket.id] = {};   
      logged_in_users[socket.id].username = username;
      logged_in_users[socket.id].user_email = user_email;
      console.log('logged_in_users AFTER ADDING new object:');
      console.log(logged_in_users);
    }
  }
};

export { heres_my_details };

我得到以下记录 - 好：

socket.id is: zhWMY0EpkNAWURN3AAAB
logged_in_users is:
{}
users_in_rooms is:
{}
live_edits_occurring is:
{}
heres_my_details:
{
  username: 'my username',
  user_email: 'my@email_address.com',
  logged_in: true
}

来自event_handler_heres_my_details.js 的错误 - 错误：

ReferenceError:logged_in_users 未定义

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环境

节点 v16.13.0
快递：^4.17.1
socket.io: ^4.3.2
socket.io-client: ^4.3.2

Answer 1

一种方法：

app.js

const express = require('express');
const { createServer } = require('http');
const app = express();
const httpServer = createServer(app);

const io = require('./ws.js')(httpServer);

ws.js

module.exports = function ws(httpServer) {

    var logged_in_users = {};
    var users_in_rooms = {};
    var live_edits_occurring = {}; 

    const { Server } = require('socket.io');
    const io = new Server(httpServer);

    httpServer.use(function(req, res, next){
        // attach io, etc. to every req object
        req.ws = {
            io,
            logged_in_users,
            users_in_rooms,
            live_edits_occurring
        };
        // call next to pass req to handler
        next();
    });
    
    io.on('connection', on_connection);

};