如何使用node.js在mysql数据库上实现推送通知系统

Question

I'm totally new to node.js and I want to implement push notification system on a MySql database. 我是node.js新手，我想在MySql数据库上实现推送通知系统。 I have a notification table in my database. 我的数据库中有一个通知表。 In this table I have store recipient_id that specify the recipient of the notification. 在此表中，我有recipient_id ，用于指定通知的收件人。 Now I want when a new notification with recipient_id is equal to current logged in user's id notify that user. 现在我想要一个带有recipient_id的新通知等于当前登录用户的id通知该用户。 Something like Stackoverflow If you are in the for example java tagged questions, every time a new question with java tag create, a notification appear on top of the page : 1 question with new activity. 像Stackoverflow这样的东西如果您在例如java标记的问题中，每次创建带有java标记的新问题时，页面顶部都会显示一条通知： 1 question with new activity. Sorry for my poor English. 抱歉我的英语不好。 Please help me to implement this system, because I'm new to it. 请帮我实现这个系统，因为我是新手。

Answer 1

I have made a simple app like your requirement. 我已经制作了一个像你的要求的简单应用程序

You can get help from following lines of code.You need to understand the basics of code. 您可以从以下代码行获得帮助。您需要了解代码的基础知识。 after that you will easily achieve your target. 之后，您将轻松实现目标。 most of things from your requirement covered in this demo app. 本演示应用程序中涵盖了您的要求中的大部分内容。

Its not a exact but you will meet your target through this. 它不是一个确切的但你会通过这个达到你的目标。

In this example a status post by any user will emit to all other users also at same time. 在此示例中，任何用户的状态帖子也将同时向所有其他用户发出。 we can manipulate it to achieve "1 new status". 我们可以操纵它来实现“1新状态”。

make a table in database where your entries to be saved CREATE TABLE status 在数据库中创建一个表，在其中保存要保存的条目CREATE TABLE status

(
    `status_id` INT NOT NULL AUTO_INCREMENT,
    `s_text` TEXT,
    `t_status` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     PRIMARY KEY ( `status_id` )
);

//server.js //server.js

var app = require("express")();
var mysql = require("mysql");
var http = require('http').Server(app);
var io = require("socket.io")(http);

/* Creating POOL MySQL connection.*/

var pool = mysql.createPool({
    connectionLimit: 100,
    host: 'localhost',
    user: 'root',
    password: '',
    database: 'fbstatus',
    debug: false
});

app.get("/", function(req, res) {
    res.sendFile(__dirname + '/index.html');
});


io.on('connection', function(socket) {
    console.log("A user is connected");

    socket.on('status added', function(status) {
        add_status(status, function(res) {
            if (res) {
                io.emit('new status', status);
            } else {
                io.emit('error');
            }
        });
    });
});

var add_status = function(status, callback) {
    pool.getConnection(function(err, connection) {
        if (err) {
            connection.release();
            callback(false);
            return;
        }
        connection.query("INSERT INTO `status` (`s_text`) VALUES ('" + status + "')", function(err, rows) {
            connection.release();
            if (!err) {
                callback(true);
            }
        });
        connection.on('error', function(err) {
            callback(false);
            return;
        });
    });
}

http.listen(3000, function() {
    console.log("Listening on 3000");
});

//index.html //index.html

<html>
  <head>
    <title>Socket.io</title>
    <script src="/socket.io/socket.io.js"></script>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
    <link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css">
    <script src = "http://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/js/bootstrap.min.js"></script>
    <script>
    $(document).ready(function(){
          var socket = io();
          $("#add_status").click(function(){
            socket.emit('status added',$("#comment").val());
          });

          socket.on('new status',function(msg){
              var count = $('#count_status').text();
              var valCount = parseInt(count);
              if(valCount>=1) {
                  valCount = valCount+1;
              } else {
                  valCount = 1;
              }
              var showMsg = '<div id="count_status"> '+valCount+' </div>  new status';
              $("#show_comments").html(showMsg);

          });
    });
    </script>
  </head>
  <body>
    <div id="comment_box" style = "padding:5%;">
      <textarea id="comment" rows="5" cols="70"></textarea><br /><br />
      <input type="button" id="add_status" value="Add">
    </div>
      <div id= "show_comments"  class = "jumbotron"></div>
  </body>
</html>

Run the app with following command node Server.js 使用以下命令节点Server.js运行应用程序

Now run http://localhost:3000/ in browser and to see the result open a new window in which you post a status and see your new status notification in both the window. 现在在浏览器中运行http：// localhost：3000 /并查看结果，打开一个新窗口，在该窗口中发布状态并在窗口中查看新状态通知。

Thanks 谢谢

Edited: This a great startup tutorial. 编辑：这是一个很棒的启动教程。 a few thing needs modification. 有些事情需要修改。

connection.release() code ends up unreadable and not working. connection.release（）代码最终无法读取且无法正常工作。 you should comets or remove it. 你应该彗星或删除它。

2.The actual output in my case: 2.我案例中的实际输出：

Answer 2

You can do it 2 ways: 你可以通过两种方式做到：

Query the server every n seconds for any new messages. 每隔n秒查询服务器以获取任何新消息。 Pass a timestamp of the last time you checked as a parameter and if any notification since the last check, return as json and display them in the client. 将上次检查的时间戳作为参数传递，如果上次检查后有任何通知，则返回json并在客户端显示。 This is called a pull strategy. 这被称为拉动策略。
Or you can use websockets which maintains a permanent connection between your client and server, and then you can send notifications to the client from your server code in real-time. 或者，您可以使用websockets来维护客户端和服务器之间的永久连接，然后您可以通过服务器代码实时向客户端发送通知。 See socket.io tutorials. 请参阅socket.io教程。 This is called a push strategy. 这称为推送策略。

如何使用node.js在mysql数据库上实现推送通知系统

问题描述

2 个解决方案

解决方案1
6 2015-03-30 13:03:53

解决方案2
2 2015-03-29 11:08:06

如何使用node.js在mysql数据库上实现推送通知系统

问题描述

2 个解决方案

解决方案1 6 2015-03-30 13:03:53

解决方案2 2 2015-03-29 11:08:06

解决方案1
6 2015-03-30 13:03:53

解决方案2
2 2015-03-29 11:08:06