How to Ignore GET requests to /robots.txt file?

I have a Node.js project. This project use local-auth with passport.js, express-session and connect-mongo package to store sessions in MongoDB sessions collection.

Each time when I update page or moving to another page, to sessions collection inserted 6 new items. Thus, across some time sessions collection becomes very large.

Code snippet for use express-session and connect-mongo:

var session = require('express-session')
var MongoStore = require('connect-mongo')(session)
app.use(session({
	resave: true,
	saveUninitialized: true,
	secret: secret.secretKey,
	store: new MongoStore({
		url: secret.database,
		autoReconnect: true
	})
}))

Morgan output in console (this happens for each page and page update):

C:\Users\User\Desktop\Project>node server.js
Node.js listening on port 3000
GET / 200 37.946 ms - 2670
GET /robots.txt 400 23.490 ms - 2328
GET /robots.txt 400 185.459 ms - 2328
GET /robots.txt 400 4.794 ms - 2328
GET /robots.txt 400 6.684 ms - 2328
GET /robots.txt 400 3.966 ms - 2328
GET /favicon.ico 400 7.314 ms - 2328
GET /robots.txt 400 3.713 ms - 2328

So, I think this happens by reason of many requests to non-existent robots.txt URL.

How can I make this file ignored in express-session?

Also I found this; http://codingteam.net/project/tapage/browse/node_modules/express/node_modules/connect/lib/middleware/session.js (lines 84 - 91):

 * Ignore Paths:
 *
 *  By default `/favicon.ico` is the only ignored path, all others
 *  will utilize sessions, to manipulate the paths ignored, use
 * `connect.session.ignore.push('/my/path')`. This works for _full_
 *  pathnames only, not segments nor substrings.
 *
 *     connect.session.ignore.push('/robots.txt');

But that’s does not work in new versions of express and express-session.

[dougwilson]

Looking how that link implements ignore, it’s identical to https://www.npmjs.com/package/ignore-paths so if that’s ehat you need, wrap this middleware with that module to ignore the paths you need.

[dougwilson]

Idk, that was never in this project.