Nodejs change global variable inside mysql query

Question

i'm trying to create a nodejs server but the following code is not working any advice?

var app = require('http').createServer();
var io = require('socket.io')(app);
var mysql = require('mysql');

var dblists = new Array();
pool=mysql.createPool({host : host,user : user,password: pass });   
pool.getConnection(function(err, connection){
    connection.query("use nodejs");
    connection.query('SELECT db_name,domain_name FROM tbl_dblist;',
    function (err, rows,f) {
        rows.forEach(function (entry) {
            dblists[entry["domain_name"]] = entry["db_name"];
        });
    });
});

console.log(dblists);

Thanks in advance] The whole code:

var dblists = new Array();

app.listen(3000);
var xsocket = io.listen(app);
//console.log('Listen On Port 3000');
var pool=mysql.createPool({host : host,user : user,password: pass });   

pool.getConnection(function(err, connection){
    connection.query("use nodejs");
    connection.query('SELECT db_name,domain_name FROM tbl_dblist;',
    function (err, rows,f) {
        rows.forEach(function (entry) {
            dblists[entry["domain_name"]] = entry["db_name"];
        });
    });
});


xsocket.set('authorization', function (handshakeData, callback) {
    callback(null, true);
});


xsocket.on('connection', function (conn) {
    xsocket.emit('list',dblists);
});

Vsevolod Goloviznin · Accepted Answer · 2014-12-26 20:50:57Z

1

getConnection is asynchronous, so your console.log fires before you get any values in your array.

If you put the console.log inside the method, it will work as epxected:

xsocket.on('connection', function (conn) {    
    pool.getConnection(function(err, connection){
        connection.query("use nodejs");
        connection.query('SELECT db_name,domain_name FROM tbl_dblist;',
        function (err, rows,f) {
            rows.forEach(function (entry) {
                dblists[entry["domain_name"]] = entry["db_name"];
            });
            xsocket.emit('list', dblists);
        });
    });        
});

edited Dec 26, 2014 at 20:50

answered Dec 26, 2014 at 20:32

Vsevolod Goloviznin

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10 Comments

Farshid Mehrtash Over a year ago

So there is no way for debugging?

Vsevolod Goloviznin Over a year ago

Why? You will have your values inside the function. If you need a synchronous way, then you should probably look at async library

Farshid Mehrtash Over a year ago

The problem is even if i emit the dblists i'm not getting anythin in my client

Vsevolod Goloviznin Over a year ago

You will need to send the data to the client inside the callback. Can you post the whole code or have you tried my suggestion>

Vsevolod Goloviznin Over a year ago

@FarshidMehrtash I've updated my answer. You will need to emit inside your callback in order to get results.

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