MongoDB collection error undefined - node.js

Question

i am facing an issue while inserting data into collection.it gives an error of cannot read property of collection undefined. provide a solution of it i try my best.
here is my code.
var http = require('http');
var fs = require('fs');
var querystring = require('querystring');
var MongoClient = require('mongodb').MongoClient;
var url ="mongodb://127.0.0.1:27017/college";
var port = 4000;
http.createServer((req,res) => {
if(req.url==="/form")
{
res.writeHead(200,{"Content-Type": "text:html"});
fs.createReadStream("./public/form.html" , "UTF-8").pipe(res);
}
if(req.method==="POST")
{
var data = " ";
req.on("data", function(chunk)
{
data += chunk;
});
req.on("end" , function(chunk){
MongoClient.connect(url , function(err,db){
if(err) throw err;
var q = querystring.parse(data).
db.collection('res').insertOne(q,function(err,res){
if(err) throw err;
console.log("data is insert");
db.close();
});
})
});
}
}).listen(port);
console.log(port);
here is erro i am facing

Answer 1

Well I would suggest your to go this way.
1- Don't use database name in when creating mongodburl i-e
replace
var url ="mongodb://127.0.0.1:27017/college";
with
var url ="mongodb://127.0.0.1:27017/";
And now when you try to connect with mongodb server you'll get mongodb constructor in the callback function so you'll have to add one extra line of code. Something like below
MongoClient.connect(url, function (err, dbC) {
if (err) throw err;
var db = dbC.db("college");
var q = querystring.parse(data).
db.collection('res').insertOne(q, function (err, res) {
if (err) throw err;
console.log("data is insert");
db.close();
});
})
This way you'll get res collection defined for the database college (I am assuming you've already defined that collection in your database with some query like db.createCollection('res')) and then it should work
Thanks