I start exploring NodeJS and working on API's sample. I am able to get req.body in post request and it is working fine but when i create function to put, my req.body come empty like {}. 
My code as below:
Post request which is working:
router.post('/',  function(req, res) {
   const name = req.body.username
   const address = req.body.address
   const phone = req.body.phone
   const values = [name, address, phone]
   const sql = "INSERT INTO userInfo (username, address, phone) VALUES (?, ?, ?)";
   res.locals.connection.query(sql, values, function (error, results, fields) {
            if(error){
                res.send(JSON.stringify({"status": 500, "error": error, "response": null}));
            } else {
                const value = {"status":"success", "userId": results.insertId}
                res.send(JSON.stringify({"status": 200, "error": null, "response": value}));
            }
        });
});
My put request which is not working:
router.put('/',  function(req, res) {
   const userId = req.body.userId
   const name = req.body.username
   const address = req.body.address
   const phone = req.body.phone
   const values = [name, address, phone, userId]
   console.log(req.body);
   const sql = "UPDATE userInfo set username =?, address = ?, phone = ?  WHERE userId = ?";
   res.locals.connection.query(sql, values, function (error, results, fields) {
            if(error){
                res.send(JSON.stringify({"status": 500, "error": error, "response": null}));
            } else {
                const value = {"status":"success", "userId": results.insertId}
                res.send(JSON.stringify({"status": 200, "error": null, "response": value}));
            }
        });
});
Please suggest me, what is wrong in that and how can i get req.body.
 
     
    