NodeJS application doesn't upload files

From the documentation:

In Express 4, req.files is no longer available on the req object by default. To access uploaded files on the req.files object, use multipart-handling middleware like busboy, multer, formidable, multiparty, connect-multiparty, or pez.

… and you don't have any such middleware loaded.

Ah, I have had the problem before.

It's probably the form type that's being sent by the client.

I would look into multer!

https://www.npmjs.com/package/multer

I think you'll find your solution with that package

you have to use multer for file upload

router.post('/upload-file', upload.single('image'))


const multer = require('multer');
const storage = multer.diskStorage({
 destination: function(req, file, cb) {
    cb(null, './uploads');
 },
 filename: function (req, file, cb) {
    cb(null , `${Date.now().toString()}-${file.originalname}`);
 }
});

const upload = multer({ storage: storage, limits: { fieldSize: 10 * 1024 * 1024 } });

Answer extracted from question, added in behalf of the asker

This is the solution and the fixed code.

const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const fs = require('fs');
const sqlite3 = require('sqlite3').verbose();
const multer = require('multer');
const path = require('path');

// Set up multer
const storage = multer.diskStorage({
    destination: './uploads/',
    filename: function (req, file, cb) {
        cb(null, file.fieldname + '-' + Date.now() + path.extname(file.originalname));
    },
});

const upload = multer({
    storage,
    dest: './uploads/',
    limits: {
        fileSize: 1000000
    },
    fileFilter: function (req, file, cb) {
        checkFileType(file, cb);
    }
});

// Check if the file is a txt file
function checkFileType(file, cb) {
    const filetypes = /\.(txt)$/;
    const extname = filetypes.test(path.extname(file.originalname).toLowerCase());
    const mimetypes = 'text/plain'

    mimetype = mimetypes === file.mimetype;

    if (mimetype && extname) {
        return cb(null, true);
    } else {
        cb('Error: Only txt files are allowed!');
    }
}

// Set up express
app.use(express.static('public'));
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());

// Create directories if they don't exist
if (!fs.existsSync('./db')) {
    fs.mkdirSync('./db');
}
if (!fs.existsSync('./uploads')) {
    fs.mkdirSync('./uploads');
}

// Connect to the database
let db = new sqlite3.Database('./db/paragraphs.db', sqlite3.OPEN_READWRITE | sqlite3.OPEN_CREATE, (err) => {
    if (err) {
        console.error(err.message);
    }
    console.log('Connected to the paragraphs database.');
});

// Create the paragraphs table if it doesn't exist
db.run('CREATE TABLE IF NOT EXISTS paragraphs (id INTEGER PRIMARY KEY AUTOINCREMENT, text TEXT, tag TEXT)', (err) => {
    if (err) {
        console.error(err.message);
    }
    console.log('Created paragraphs table.');
});

// Home page
app.get('/', (req, res) => {
    res.sendFile(__dirname + '/index.html');
    /*
    res.write('<h1>Welcome to the Paragraphs App</h1>' +
        '<a href="/file_uploading">Upload a File</a><br>' +
        '<a href="/visualize_paragraphs">Visualize Paragraphs</a><br>' +
        '<a href="/tag_paragraphs">Tag Paragraphs</a>');
    res.end();
     */
});

app.get('/file_uploading', (req, res) => {
    res.sendFile(__dirname + '/file_uploading.html');
});

app.post('/upload_file', upload.single('filetoupload'), async (req, res) => {
    let filename = req.file.filename;

    res.send('File uploaded!<br>' +
        '<a href="/file_uploading">Upload Another File</a><br>' +
        '<a href="/visualize_paragraphs">Visualize Paragraphs</a><br>' +
        '<a href="/tag_paragraphs">Tag Paragraphs</a>');

    fs.readFile('./uploads/' + filename, {encoding: 'utf-8'}, (err, data) => {
        if (err) {
            return console.log(err.message);
        }
        let lines = data.split('\r\n');
        for (let i = 0; i < lines.length; i++) {
            db.run('INSERT INTO paragraphs (text) VALUES (?)', [lines[i]], (err) => {
                if (err) {
                    return console.log(err.message);
                }
            });
        }
    });
});

app.get('/visualize_paragraphs', (req, res) => {
    db.all('SELECT * FROM paragraphs', (err, rows) => {
        if (err) {
            throw err;
        }
        rows.forEach((row) => {
            res.write('<h1>Visualize Paragraphs</h1>');
            res.write(row.text + '<br>');
        });
        res.end();
    });
});

app.get('/tag_paragraphs', (req, res) => {
    let paragraph_id = req.query.paragraph_id;
    let tag = req.query.tag;
    if (paragraph_id && tag) {
        db.run('UPDATE paragraphs SET tag = ? WHERE id = ?', [tag, paragraph_id], function (err) {
            if (err) {
                return console.log(err.message);
            }
            console.log(`Row(s) updated: ${this.changes}`);
        });
        res.send('<h1>Tag Paragraphs</h1>' +
            '<p>Paragraph ' + paragraph_id + ' has been tagged as ' + tag + '</p>');
    } else {
        db.all('SELECT * FROM paragraphs', (err, rows) => {
            if (err) {
                throw err;
            }
            res.write('<h1>Tag Paragraphs</h1>' +
                '<table>');
            rows.forEach((row) => {
                res.write('<tr><td>' + row.id + '</td><td>' + row.text + '</td></tr>');
            });
            res.write('</table>' +
                '<form action="/tag_paragraphs" method="get">' +
                '<label for="paragraph_id">Paragraph ID:</label>' +
                '<input type="text" id="paragraph_id" name="paragraph_id"><br>' +
                '<label for="tag">Tag:</label>' +
                '<input type="text" id="tag" name="tag"><br>' +
                '<input type="submit" value="Submit">' +
                '</form>');
            res.end();
        });
    }
});

app.listen(3000, () => {
    console.log('Example app listening on port 3000!');
});