如何使用node-js和socket.io在mysql数据库中插入新记录时通知和更新客户端

Question

无法使用mysql节点js和socket.io 更新客户端中的记录列表

大家好，我想在mysql数据库中插入新记录时更新客户端，我使用node-js和socket.io.

我能为这个问题做些什么，我是nodejs和socket的新手，如果我的代码太混乱，请原谅我。我找了很多，但什么也没找到。任何建议都将是有益的。这是我的server.js文件：

var mysql = require('mysql') ;
var io = require('socket.io').listen(3000) ;
var db = mysql.createConnection({
host:'localhost',
user:'root',
database:'mygame'
});
db.connect(function(err){
if(err) console.log(err);
console.log("Connected Successfully To The Database");
});
// Here We Need List Of Competitions To Emit To All Clients 
var Competitions = [] ;
var isInitCompetitions = false ;
var socketCount = 0 ;
//
io.sockets.on('connection',function(socket){
Competitions = [];
db.query("SELECT * FROM comps WHERE compstatus='1'").on(
'result',function(data) {
Competitions.push(data) ;
}
).on(
'end',function(){
socket.emit('all competitions',Competitions);
}
) ;
socketCount++ ;
io.sockets.emit('Another User Is Connected : ' ,socketCount);
console.log('One User Is Connected');
socket.on('disconnect',function() {
io.sockets.emit('One User Left : ' ,socketCount);
});
function checkNewCompetitions() {
socket.on('newcomp',function(){
db.query("SELECT * FROM comps WHERE compstatus='1'").on(
'result',function(data) {
Competitions = [];
Competitions.push(data) ; 
}
).on(
'end',function(){
socket.emit('all competitions',Competitions);
console.log('Number Of Competitions in Flow : ' , Competitions.length) ;
}
) ;
});
}
setInterval(checkNewCompetitions,3000);

});

这是我的index.html文件：

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script src="http://localhost:3000/socket.io/socket.io.js"></script>
<script>
$(document).ready(function() {
var socket = io.connect('http://localhost:3000');
socket.on('all competitions',function(data) {
var html = ''  ;
for(var i = 0 ;i < data.length; i++){
html += '<li>'+data[i].id + '</li>';
}
$('#competitions').html(html);
});
socket.on('newcomp',function(data) {
var html = ''  ;
for (let index = 0; index < data.length; index++) {
const element = data[index];
html += '<li>' + data[index].id + '</li>';
}
$('#competitions').html(html);
});
});
</script>
<p>This is List Of Competitions</p>
<ul id="competitions"></ul>

我运行了这个代码，但我得到了这个错误：

(node:8628) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 newcomp listeners added. Use emitter.setMaxListeners() to increase limit

多亏了这个伟大的社区，我能为这个问题做些什么呢。

Answer 1

每3秒添加一个新的事件侦听器，从而发生MaxListenersExceedWarning。每3秒调用checkNewComputions是可以的。如果有新的comp，你必须用socket.emit('newComp')发出一个新的comp事件

socketCount++ ;
io.sockets.emit('Another User Is Connected : ' ,socketCount);
console.log('One User Is Connected');
socket.on('disconnect',function() {
io.sockets.emit('One User Left : ' ,socketCount);
});
function checkNewCompetitions() {
/// Every 3 seconds you check the database for new comps
db.query("SELECT * FROM comps WHERE compstatus='1'").on(
'result',function(data) {
Competitions = [];
Competitions.push(data) ; 
}
).on(
'end',function(){
// here you have to call socket.emit('newComp') 
// so the client gets the event a new comp is inserted in database. 
socket.emit('all competitions',Competitions);
console.log('Number Of Competitions in Flow : ' , Competitions.length) ;
}
) ;
}
setInterval(checkNewCompetitions,3000);
});

我找不到你在哪里发出"newcomp"事件。所以('newcomp'..)上的套接字永远不会被称为