Upload file using multer

upload_file_multer.js

const path = require('path')
const fs = require('fs')

const express = require('express')
const bodyParser = require('body-parser')
const multer = require('multer');
const crypto = require('crypto');

const db = require('./db/db.json')

const port = process.env.PORT || 3000
const host = process.env.PORT || 'localhost'
const baseURL = `http://${host}:${port}`
const app = express()

// create application/json parser
app.use(bodyParser.json({ type: 'application/json' }))

// serve www
app.use('/', express.static(path.join(__dirname, 'www')))
// serve upload to access uploaded
app.use('/upload', express.static(path.join(__dirname, 'upload')))

// serve upload middleware
const storage = multer.diskStorage({
    destination: function (req, file, cb) {
      cb(null, 'upload')
    },
    filename: function (req, file, cb) {
        const name = file.fieldname + Date.now()
        const hashed = crypto.createHash('md5').update(name ).digest("hex");
        cb(null, hashed + path.extname(file.originalname))
    }
})
   
const upload = multer({ storage: storage })

app.get('/ping', (req, res) => res.status(200).json({ping: "pong"}))
app.post('/api/users', (req, res) => {
    // get body payload
    const { name, email, npm, fotoURL } = req.body
    const id = (new Date()).getTime()
    const user = { id, name, email, npm, fotoURL }
    // save user to db
    db.users.push(user)
    return res.status(200).json(user)
})

app.post('/api/save/file', upload.single('biodata'), (req, res) => {
    const file = req.file
    if (!file) return res.status(400).json({"error": "not a file"})

    // save file path to db files
    db.files.push({
        id: file.filename,
        path: `/upload/${file.filename}`
    })

    res.status(200).json({ "path": `${baseURL}/upload/${file.filename}` })
})

// perists db on terminate
process.on('SIGINT', function() {
    console.log("\nsave to db...");
    fs.writeFileSync(path.join('db', 'db.json'), JSON.stringify(db, undefined, 2))
    process.exit();
});

app
    .listen(port, () => console.log(`listening at :${port}`))