Insert data in mongodb using Socket.io - node.js

Question

i am developing simple chat application and i want to store messages in mongoDb.
but i am getting error when i run this code.
can not read property '_id 'of undefined. i already create one collection call chat.
var MongoClient= require('mongodb').MongoClient;
var assert=require('assert');
var ObjectId= require('mongodb').ObjectId;
var bodyParser= require('body-parser');
var express = require('express'),
app=express();
server=require('http').createServer(app),
io= require('socket.io').listen(server),
app.use(bodyParser.urlencoded({extended:false}));
var mongo=require('mongodb');
users = {};
url='mongodb://localhost:27017/anant';
server.listen(9000, function(){
var host= server.address().address;
var port=server.address().port;
console.log("save app listen on http://%s:%s", host , port);
});
/*var server = app.listen(9000, function(){
var host= server.address().address;
var port=server.address().port;
console.log("save app listen on http://%s:%s", host , port);
});*/
app.get('/', function(req, res){
res.sendFile(__dirname + '/index.html');
});
io.sockets.on('connection', function(socket){
socket.on('new user', function(data , callback){
if(data in users){
callback(false);
}else{
callback(true);
socket.nickname= data;
users[socket.nickname]= socket;
updatenicknames();
}
});
io.sockets.on('send request', function(data , callback){
var name=data;
console.log(data);
});
socket.on('send message', function(data , callback){
var msg=data.trim();
if(msg.substr(0,3) === '/w '){
msg = msg.substr(3);
var ind = msg.indexOf(' ');
console.log(ind);
console.log("got it after ind ");
if(ind !== -1)
{
var name=msg.substr(0, ind);
var msg=msg.substring(ind + 1);
console.log(name);
console.log(msg);
if(name in users){
console.log("got it in if name condition");
users[name].emit('wishper', {msg: msg , nick: socket.nickname} );
console.log('whisper..! ');
} else
{
callback("enter a vlid user");
}
} else{
callback('please enter message for your wishper');
}
}else {
insertData(data);
io.sockets.emit('new message', {msg: msg , nick: socket.nickname} );
}
});
function updatenicknames(){
io.sockets.emit('usernames', Object.keys(users));
}
function insertData(data)
{
MongoClient.connect(url, function(err, db){
console.log(data);
db.collection('chat').save(data.msg , (err,result)=>{
if(err){
console.log("not inserted");
}else {
console.log("inserted");
}
});
});
}
socket.on('disconnect', function(data){
if(!socket.nickname) return;
delete users[socket.nickname];
updatenicknames();
});
});

Answer 1

It's because you are passing a string data, to your insertData function (judging by your code, I guess you are supposing that data is actually an object).
Then you are giving data.msg, which is obviously undefined, as the first argument of the save methods, which is expecting you to provide a valid object here.
Please also note that you are using the save method on a newly created document, instead of using insertOne.
As you can see in the api documentation, using save is now deprecated. (I guess you are using the last version which is currently 2.1)