server.js

const express = require('express');
const app = express();
const port = process.env.PORT || 5000;
var mongoose = require("mongoose");
var bodyParser = require('body-parser');
const morgan = require('morgan');
const session = require('express-session');
const dbConnection = require('./client/src/config/userDataConnection');
const MongoStore = require('connect-mongo')(session);
const passport = require('./client/src/passport');
//const User = require('./client/src/routes/user');
const User = require('./client/src/models/user');


// Require all models
var Sensor = require("./client/src/models/sensorModel");

// Sessions
app.use(
	session({
		secret: 'projectsix', //pick a random string to make the hash that is generated secure
		store: new MongoStore({ mongooseConnection: dbConnection }),
		resave: false, //required
		saveUninitialized: false //required
	})
)

// Passport
app.use(passport.initialize());
app.use(passport.session()); // calls serializeUser and deserializeUser

app.use(morgan('dev'))

// body parser things
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json())

//connect to mongo
mongoose.connect("mongodb+srv://Rebecca:cupboard@cluster0-vfyb8.mongodb.net/test?retryWrites=true&w=majority", { useNewUrlParser: true });

// console.log that your server is up and running
app.listen(port, () => console.log(`Listening on port ${port}`));

// create a GET route
app.get('/express_backend', (req, res) => {
    //res.send({ express: 'YOUR EXPRESS BACKEND IS CONNECTED TO REACT' });
     Sensor.find().then(found => {
        //console.log(found);

         res.send({express: found});
    });
  
});

app.use( (req, res, next) => {
    console.log('req.session', req.session);
    return next();
  });

  /*---- ROUTE TO CREATE NEW SENSOR PRODUCT ----*/
app.post('/new_sensor', (req, res) => {
    // Create a new mongo sensor entry using data
    Sensor.findOneAndUpdate({product:req.body.item}, {reading:100, reorderLink:req.body.link},{upsert:true})
    .then(function(sensorReading) {
        // If saved successfully, send the the new User document to the client
        console.log(sensorReading);
    })
    .catch(function(err) {
        // If an error occurs, send the error to the client
        console.log(err);
    });
})

// app.post('/signup', (req, res) => {
//     // Create a new mongo sensor entry using data
//     User.create({username:req.body.username, password:req.body.password})
//     .then(function(newUser) {
//         // If saved successfully, send the the new User document to the client
//         console.log(newUser);
//     })
//     .catch(function(err) {
//         // If an error occurs, send the error to the client
//         console.log(err);
//     });   
// })

app.post('/signup', (req, res) => {
    console.log('user signup');

    const { username, password } = req.body
    // ADD VALIDATION
    User.findOne({ username: username }, (err, user) => {
        if (err) {
            console.log('User.js post error: ', err)
        } else if (user) {
            res.json({
                error: `Sorry, already a user with the username: ${username}`
            })
        }
        else {
            const newUser = new User({
                username: username,
                password: password
            })
            newUser.save((err, savedUser) => {
                if (err) return res.json(err)
                res.json(savedUser)
            })
        }
    })
})