`this` is undefined in expressJS route handler : <p><strong>groups.js</strong></p>

<pre><code>class groupsCtrl {
  constructor() {
    this.info = "test";
  }

  get(res, req) {
    console.log("LOG ! ", JSON.stringify(this));
  }
}
module.exports = new groupsCtrl(); //singleton
</code></pre>

<p><strong>routes.js</strong></p>

<pre><code>var express = require('express');
var router = express.Router();

var groupsCtrl = require('controllers/api_admin/groups.js');
router.get('/groups/', groupsCtrl.get);
</code></pre>

<p>This logs <code>LOG ! undefined</code></p>

<p>How can I have access to <code>this</code> in my controller class ?</p>
