Node.js / Socket.io / Mysql to print as JSON

Question

SOLVED: Answer is: socket.on('clients', function(data) { document.write(JSON.stringify(data)); });

I want to get ouput like this (only the part in bold) on the screen as JSON:

debug - websocket writing 5:::{"name":"clients","args":[[{"id":6,"name":"demo 3"},{"id":7,"name":"demo1"}]]}

I must be missing something cause I just can't understand why it doesn't print as JSON. I have 3 files:

app.js (server) :

var fs = require('fs');
var db = require("./db.js");

var http = require('http').createServer(function handler(req, res) {
    fs.readFile(__dirname + '/index.html', function (err, data) {
        if (err) {
            res.writeHead(500);
            return res.end('Error loading index.html');
        } else {
            res.writeHead(200);
            res.end(data);
        }
    });
}).listen(3000);
// -----------------------------------
var io = require('socket.io').listen(http);
io.sockets.on('connection', function (client) {
    console.log('Client connected');
    db.get_employees(function (employees) {
        io.sockets.emit('clients', employees);
    });
});

db.js (connect to database) :

// -----------------------------------
var mysql = require('mysql');
var client = mysql.createConnection({
    user: 'xxxx',
    password: 'yyyy',
    host: '123.45.67.89',
    database: 'zzzz'
});
// -----------------------------------
exports.get_employees = function (callback) {
    client.query("select id, name from clients", function (err, results, fields) {
        callback(results);
    });
}

And index.html :

<script src="http://192.168.2.25:3000/socket.io/socket.io.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>

<script>
 $(document).ready(function() {
  var socket  = io.connect('http://192.168.2.25:3000');
  socket.on('clients', function(data) {
   $.each(data, function(i, obj) {
        //  document.write(obj);      // Gets me [object Object][object Object]
        //  document.write(obj.name)  // Gets me name column
        //  document.write(obj.email) // Gets me email column
        //  document.write(obj.xxxxx) // Gets me xxxxx column
        //  document.write(JSON.stringify(obj));   //Prints as JSON but structure is   wrong and it is a html string not as JSON output

     });
  });
});
</script>

I am having trouble figuring why I cannot print it as JSON. See index.html commented lines. As well I want it to be a clean JSON output of my database and not as html.

The io.sockets.emit('clients', employees); in the App.js emits a correct json format I want but I can't get it outputted.I get [Object Object] or Undefined. There must be a way to do it because if I have to structure it manually it would make it speed inefficient.

Any help would be appreciated.

JSON.stringify is the correct function to use. What do you mean it prints it as html? Can you provide an example of what it outputs? — Rei Mavronicolas, Jun 25 '13 at 10:22
It outputs: {"id":6,"name":"demo3"}{"id":7,"name":"demo1"} but should output at like this: {"id":6,"name":"demo3"},{"id":7,"name":"demo1"} (with a comma) but idealy I want it like this like the debug emit prints in the console: {"name":"clients","args":[[{"id":6,"name":"demo 3"},{"id":7,"name":"demo1"}]]} however the page is like html text printed. I need it as JSON (how do I change the header of the page too) — Marty Balandis, Jun 25 '13 at 10:29
I can add , manually but then it will add to the end as well so I need to add another function that removes it and then converts it to JSON header. Seems too many workarounds needed, there must be a simpler and less resource consuming way. — Marty Balandis, Jun 25 '13 at 10:31
It's because you're outputting each JSON object on it's own. Try doing stringify on the data variable e.g. socket.on('clients', function(data) { document.write(JSON.stringify(data)); }); — Rei Mavronicolas, Jun 25 '13 at 10:41
The funny thing is that I tried something similar before but didn't work. This actually works! Thank you!. I'll mark this as solved! — Marty Balandis, Jun 25 '13 at 10:48
I'll convert the comment into an answer for the sake of completeness. — Rei Mavronicolas, Jun 25 '13 at 11:49
@MartyBalandis it is better to accept a answer instead of prefixing question with solved so please do that — Gaurav, Jun 26 '13 at 07:04
@Gaurav What answer? The whole answer was in comments which helped, so how could I even accept it? -.- — Marty Balandis, Jun 28 '13 at 13:29
Reinard Mavronicolas posted the answer later so you can accept it now...or still not able to see the answer?? — Gaurav, Jun 30 '13 at 05:18

score 1 · Accepted Answer · answered Jun 25 '13 at 11:49

1

It's because you're outputting each JSON object on it's own. Try doing stringify on the "data" variable e.g.

$(document).ready(function() {
  var socket  = io.connect('http://192.168.2.25:3000');
  socket.on('clients', function(data) {
    document.write(JSON.stringify(data));
  });
});

answered Jun 25 '13 at 11:49

Rei Mavronicolas

1,387
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12

This is giving a circular reference error: TypeError: Converting circular structure to JSON – Sumit Bisht Apr 25 '14 at 05:55
@SumitBisht - the error you're getting is not due to a problem with the above code. It means you have a circular reference in the object (in this case 'data') you're trying to stringify. Do a search for the error and you'll probably get a better explanation. – Rei Mavronicolas Apr 25 '14 at 07:43
Oh,sorry got it.. I was trying to get information about the socket object itself. Getting data is fine, thanks – Sumit Bisht Apr 25 '14 at 10:02

Node.js / Socket.io / Mysql to print as JSON

1 Answers1