PASSPORT & express-session config e models

app.js

const passport = require("passport");
const { LocalStrategy } = require("passport-local");
const User = require("./models/user");
const Employee = require("./models/employee");
const session = require('express-session');

passport.use(new LocalStrategy(username, password, done) => {
  User.findOne({ username })
    .then(user => done(null, user && User.isPasswordValid(user, password) ? user : false))
    .then(err => done(err))
});

passport.serializeUser((user, cb) => cb(null, user.id));
passport.deserializeUser((id, cb) => User.findById(id, (err, user) => err ? cb(err) : cb(null, user)));

employee.js

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


    var EmployeeSchema = new mongoose.Schema({
        username:String,
        password:String,
        firstname:String,
        lastname:String,
        birth:String,
        adress:String,
        role:String,
        education:String,
        experience:String

    })

EmployeeSchema.plugin(passportLocalMongoose);
module.exports = mongoose.model("Employee", EmployeeSchema);

user.js

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

    var UserSchema = new mongoose.Schema({
        username:String,
        password:String,
        isAdmin: {type:Boolean, default:false}
    })

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