Node.js：在express.js路由中使用Socket.io将消息发送到特定客户端

Question

我做了一个非常随意的评论系统，现在我想添加回复。 因此，当某人对他人的评论发表回复时，必须通知该用户某人已回复了他们的评论。 为此，当回复者单击回复按钮时，会向服务器发出AJAX发布请求，然后服务器需要获取第一个评论者的ID，并使用socket.io向他们发送响应文本（socket.io为如果有另一种方法可以通过另一个模块发送回复文本或表达自己，则不需要使用。 到目前为止，这是我的代码：

app.post('/reply', function(req, res){
  var commenterId = req.body.userId; // this is the id of the original commenter, not the replier
  User.findOne({'_id':commenterId}, function(err, user){
    user.send({'replied': req.user._id}); // this is what I need to do, and
  //I don't know if this specific code works and that's why I'm asking if there is a way to do it with socket.io,
  // io.to(socketId).emit('reply', 'some reply text here...'); // but if I do this I don't know how to get the socketId!
  //Is there even a way to do this? Maybe with another module,
  //or some express function I don't know about? And if it is done with express how would
  //the client side code, look like? Thank you!
  });
  res.end();
});

Answer 1

//app.js file   
var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io').listen(server);
var routes = require('./routes/routes')(io);
app.use('/', routes);

//router file
var express = require('express');
var router = express.Router();
var _socket = null;

//list of socket users.once they logout delete the socket by 
//delete users[_socket.userid];
var users = {};

var returnRouter = function(io) {

    io.sockets.on('connection', function (socket) {
        //now _Socket is available inside routes
       _socket =  socket;
    });

    router.post('/login', function(req, res) {
        //authentication logic
        User.findOne({'email': req.body.email}, function (err, user) {

           //userid must be unique
           _socket.userId= user.userId
           //set session variable to store id of the user
           req.session.userId = user.userId;
           //now every user has a socket associated with their id
           users[_socket.userId] = _socket;
        });
    });

    router.post('/reply', function (req, res) {
       var commenterId = req.body.userId;
       User.findOne({'_id': commenterId}, function (err, user) {

       // you can get the id of the logged in user that is the creator
       //of the original post from req.session.userId
       //if you have implemented session store

       //the commenter user object is obtained from findOne method
       users[req.session.userId].emit('notification', {
         notification: user.username+' commented on your post'
       }});
       });
       res.end();
    });

    return router;
};
module.exports = returnRouter;