Question

我创建了一个数据库连接，并从服务器端的db中获取数据。如何将我的数据从服务器端传递到node.js中的客户端javascript。请帮帮我，我读了很多谷歌搜索，但没有找到任何有用的东西。我正在使用Emitter参加我的活动。现在它正在使用serveride，我无法将数据传递给客户端。

这是我的代码：

var dbrows;

// Connecting to Database.
var mysql      = require('mysql');
var connection = mysql.createConnection({
  host     : 'localhost',
  user     : 'root',
  password : ''
});
var  DBName   = 'use ChatDB';

connection.connect();

connection.query(DBName);

connection.query('SELECT * from chat', function(err, rows, fields) {
  if (err) throw err;

  dbrows = rows;

});

connection.end();

// Event Emitter emits out pre-defined events.

var EventEmitter = require("events").EventEmitter;

var Emitter = new EventEmitter();
Emitter.on('ChatUsers', function () {
    console.log(dbrows);
});

Answer 1

如果您不必使用Emitter，建议您使用socket.io等WebSocket库。它使用简单。对于您的代码，您可以编写如下内容：

io.on('connection', function (socket) {
  socket.on('sendUsers', function (data) {
    connection.connect();

    connection.query(DBName);

    connection.query('SELECT * from chat', function(err, rows, fields) {
      if (err) throw err;

      socket.emit('sendUsers', rows);

    });
    connection.end();

  });
});

在客户端：

socket.on('sendUsers', function(data){
    console.log(data); // here you have your db records.
});

此处有更多信息和示例：

Socket.io

Answer 2

这是服务器端代码：

// This file is required by app.js. It sets up event listeners
// for the two main URL endpoints of the application - /create and /chat/:id
// and listens for socket.io messages.

// Use the gravatar module, to turn email addresses into avatar images:

var gravatar = require('gravatar');

// Export a function, so that we can pass 
// the app and io instances from the app.js file:

module.exports = function(app,io){

app.get('/', function(req, res){

    // Render views/home.html
    res.render('home');
});

app.get('/create', function(req,res){

    // Generate unique id for the room
    var id = Math.round((Math.random() * 1000000));

    // Redirect to the random room
    res.redirect('/chat/'+id);
});

app.get('/chat/:id', function(req,res){

    // Render the chat.html view
    res.render('chat');
    Emitter.emit('ChatUsers');

});

// Initialize a new socket.io application, named 'chat'
var chat = io.of('/socket').on('connection', function (socket) {

    // When the client emits the 'load' event, reply with the 
    // number of people in this chat room

    socket.on('load',function(data){

        if(chat.clients(data).length === 0 ) {

            socket.emit('peopleinchat', {number: 0});
            Emitter.emit("ChatUsers");
        }
        else {

            socket.emit('peopleinchat', {
                number: 1,
                user: chat.clients(data)[0].username,
                avatar: chat.clients(data)[0].avatar,
                id: data
            });
        }

    });

// THIS IS YOUR CODE WHAT YOU WROTE FOR ME:
    socket.on('sendUsers', function (data) {

            var mysql      = require('mysql');
    var connection = mysql.createConnection({
          host     : 'localhost',
          user     : 'root',
          password : '',
        });
             var  DBName   = 'use ChatDB';

    connection.connect();

    connection.query(DBName);

    connection.query('SELECT * from chat', function(err, rows, fields) {
      if (err) throw err;

      socket.emit('sendUsers', rows);

    });
    connection.end();

    });

    // When the client emits 'login', save his name and avatar,
    // and add them to the room
    socket.on('login', function(data) {

    console.log(data);

    // Use the socket object to store data. Each client gets
    // their own unique socket object

        socket.username = data.user;
        socket.room = data.id;
        socket.avatar = gravatar.url(data.avatar, {s: '140', r: 'x', d: 'mm'});

        // Tell the person what he should use for an avatar
        socket.emit('img', socket.avatar);


        // Add the client to the room
        socket.join(data.id);

        if(chat.clients(data.id).length >= 2 ) {

            console.log(data.id);

            var usernames = [],
                avatars = [];

            usernames.push(chat.clients(data.id)[0].username);
            usernames.push(chat.clients(data.id)[1].username);

            avatars.push(chat.clients(data.id)[0].avatar);
            avatars.push(chat.clients(data.id)[1].avatar);

            // Send the startChat event to all the people in the
            // room, along with a list of people that are in it.

            chat.in(data.id).emit('startChat', {
                boolean: true,
                id: data.id,
                users: usernames,
                avatars: avatars
            });
        }

    });

    // Somebody left the chat
    socket.on('disconnect', function() {

        // Notify the other person in the chat room
        // that his partner has left

        socket.broadcast.to(this.room).emit('leave', {
            boolean: true,
            room: this.room,
            user: this.username,
            avatar: this.avatar
        });

        // leave the room
        socket.leave(socket.room);
    });


    // Handle the sending of messages
    socket.on('msg', function(data){

        // When the server receives a message, it sends it to the other person in the room.
        socket.broadcast.to(socket.room).emit('receive', {msg: data.msg, user: data.user, img: data.img});
    });
});
};

Node.js将数据从服务器端传递到客户端

2 个答案: