server.js

const express = require('express'),
    path = require('path'),
    mongoose = require('mongoose'),
    cors = require('cors'),
    bodyParser = require('body-parser'),
    dbConfig = require('./database/db'),
    morgan = require('morgan');
    require('dotenv').config();

// Connecting with mongo db
mongoose.Promise = global.Promise;
mongoose.connect(dbConfig.db, {
    user: process.env.DB_USER,
    pass: process.env.DB_PASS,
    useFindAndModify: false,
    useNewUrlParser: true,
    useUnifiedTopology: true
}).then(() => {
    console.log('Database sucessfully connected')
},
    error => {
        console.log('Database could not connected: ' + error)
    }
)

//Middelware
const studentRoute = require('./routes/student.route')
const app = express();

app.use(morgan('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: false
}));
app.use(cors());
app.use('/', express.static(path.join(__dirname, 'dist')));
app.use('/api', studentRoute)

// Create port
const port = process.env.PORT || 4000;
const server = app.listen(port, () => {
    console.log('Connected to port ' + port)
})

// Find 404 and hand over to error handler
app.use((req, res, next) => {
    next(createError(404));
});

// error handler
app.use(function (err, req, res, next) {
    console.error(err.message); // Log error message in our server's console
    if (!err.statusCode) err.statusCode = 500; // If err has no specified error code, set error code to 'Internal Server Error (500)'
    res.status(err.statusCode).send(err.message); // All HTTP requests must have a response, so let's send back an error with its status code and message
});