authentication error with passport-local in mongoose

Question

I made a simple application with my course attendant in js and ejs i followed all the steps with him but i get error when i put the middle ware of a get route

     var    express                 = require('express'),
        mongoose                = require('mongoose'),
        passport                = require("passport"),
        bodyParser              = require("body-parser"),
        User                    = require("./models/user.js");
        LocalStrategy           = require("passport-local"),
        passportLocalMongoose   = require("passport-local-mongoose"),
        app = express()
;        
mongoose.connect("mongodb://localhost:27017/auth_demo_app", {
useUnifiedTopology: true,
useNewUrlParser: true,
useFindAndModify: false
});
 app.set("view engine", 'ejs');
 app.use(require("express-session")({
    secret: "Rusty is thajaodjo asdoj ofadsj",
    resave: false,
    saveUninitialized: false
}));
 app.use(passport.initialize());
 app.use(passport.session());
 app.use(bodyParser.urlencoded({extended: true}));

passport.use(new LocalStrategy(User.authenticate()));
passport.serializeUser(User.serializeUser());
passport.serializeUser(User.deserializeUser());
// ===================
//      ROUTES
// ===================
app.get("/", function(req, res){
     res.render("home");
});
app.get("/register", function(req, res){
    res.render("register");
});
app.post("/register", function(req, res){
    var userName = req.body.username;
    var password = req.body.password;
    User.register(new User({username: userName}), password, function(err, user){
        if(err){
            console.log(err);
            return res.render('register');
        }
        passport.authenticate("local")(req, res, function(){
            res.redirect("/secret");
        });
    });
});
app.get("/logout", function(req, res){
    req.logout();
    res.redirect("/");
});
app.get("/login", function(req, res){
    res.render("login");
});
// app.get("/secret", isLoggedIn, function(req, res){
//     res.render("secret");
// });
app.get("/secret", isLoggedIn, function(req, res){
    // res.render("secret");
    console.log("logged in");
});
app.post("/login", passport.authenticate("local", {
    successRedirect: "/secret",
    failureRedirect: "/login"
}), function(req, res){
    console.log("success");
});
function isLoggedIn(req, res, next){
    if(req.isAuthenticated()){
        return next();
    }
    res.redirect("/login");
}
function serverStarted(){
    console.log("Server Started Successfully.");
}
 app.listen(3000, serverStarted);

the ./models/user.js:

    var mongoose = require("mongoose");
var passportLocalMongoose = require("passport-local-mongoose");



var UserSchema = new mongoose.Schema({
    username: String,
    password: String
});

UserSchema.plugin(passportLocalMongoose);

module.exports = mongoose.model("User", UserSchema);

and this is the error:

 Error: Failed to deserialize user out of session
        at pass (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\passport\lib\authenticator.js:344:19)
        at Authenticator.deserializeUser (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\passport\lib\authenticator.js:362:5)
        at SessionStrategy.authenticate (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\passport\lib\strategies\session.js:60:10)
        at attempt (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\passport\lib\middleware\authenticate.js:366:16)
        at authenticate (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\passport\lib\middleware\authenticate.js:367:7)
        at Layer.handle [as handle_request] (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\layer.js:95:5)
        at trim_prefix (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\index.js:317:13)
        at C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\index.js:284:7
        at Function.process_params (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\index.js:335:12)
        at next (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\index.js:275:10)
        at initialize (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\passport\lib\middleware\initialize.js:53:5)
        at Layer.handle [as handle_request] (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\layer.js:95:5)
        at trim_prefix (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\index.js:317:13)
        at C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\index.js:284:7
        at Function.process_params (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\index.js:335:12)
        at next (C:\Users\Mohamed Mostafa\Desktop\FTP Synced\Authentication\node_modules\express\lib\router\index.js:275:10)

Note: This error occurs while i am logged in only and when i am not logged in it redirect me to login page so whats the problem anyone solve it for me please

Answer 1

I found the solution which i wasnt calling deserialize user

passport.serializeUser(User.serializeUser());
passport.serializeUser(User.deserializeUser());

The right:

passport.serializeUser(User.serializeUser());
passport.deserializeUser(User.deserializeUser());