TypeError: object is not a function in node Js

I'm a beginner to nodejs and i'm developing a REST api to interact with mongodb. I used express and mongoose as explained in following tutorial :

https://codeforgeek.com/2015/08/restful-api-node-mongodb/

I have setup mongo db and here is my server code in node js :

var express     =   require("express");
var app         =   express();
var bodyParser  =   require("body-parser");
var router      =   express.Router();
var mongoOp     =   require("./models/mongo");
//var user        =   require("./Entities/User");
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({"extended" : false}));
router.get("/",function(req,res){
    res.json({"error" : false,"message" : "Hello World"});
});
router.route("/users")
    .get(function(req,res){
        var response = {};
        mongoOp.find({},function(err,data){
        // Mongo command to fetch all data from collection.
            if(err) {
                response = {"error" : true,"message" : "Error fetching data"};
            } else {
                response = {"error" : false,"message" : data};
            }
            res.json(response);
        });
    })
    .post(function(req,res){
        var db = new mongoOp();
        var response = {};
        // fetch email and password from REST request.
        // Add strict validation when you use this in Production.
        db.userEmail = req.body.email;
        // Hash the password using SHA1 algorithm.
        db.userPassword =  require('crypto')
                          .createHash('sha1')
                          .update(req.body.password)
                          .digest('base64');
        db.save(function(err){
        // save() will run insert() command of MongoDB.
        // it will add new data in collection.
            if(err) {
                response = {"error" : true,"message" : "Error adding data"};
            } else {
                response = {"error" : false,"message" : "Data added"};
            }
            res.json(response);
        });
    });
app.use('/',router);
app.listen(3000);
console.log("Listening to PORT 3000");

and here is my mongo module

var mongoose = require("mongoose");
mongoose.connect("mongodb://localhost:27017/Appdb");
//Create instance of Schema
var mongoSchema = mongoose.schema;
//Create Schema
var userSchema = {
    "userEmail":String,
    "userPassword":String
}
//Create model if not exists.
module.export = mongoose.model('userLogin',userSchema);

When i used RESTClient (an addon in firefox to test REStful application) it gives following error :

TypeError: object is not a function at E:\node\server.js:30:18
at Layer.handle [as handle_request] (E:\node\node_modules\express\lib\router\layer.js:95:5) .........

Can anyone help me please...