Update index.js

routes/index.js

@@ -103,16 +103,28 @@ router.post('/customer_registration', function (req, res, next) {
         Email:email,
         Password:password
      }
-     Farmer.create(newlist,function(err,newone){
+    Customer.findOne({username: req.body.uname}, function(err,uname)    // checked where the entered username is already in customers list
+     {
+       if(uname)
+       {
+         res.send('A customer is already having this username please enter another username');
+ 
+       }
+       else 
+       {
+          Customer.create(newlist,function(err,newlyCreated)
+         {
         if (err) 
         {
-            console.log(err);
+            console.log(err); 
         }
         else
         {
             res.redirect("/");
         }
     });
+    }
 });
+     });
 
 module.exports = router;