Serving files and handling multipart uploads in Express

Serving Static Files and Handling Uploads

Use express.static to serve files from a directory. Use multer for handling file uploads from multipart requests.

app.use('/static', express.static(path.join(__dirname, 'public')));

app.get('/download/report', (req, res) => {
  res.sendFile(path.join(__dirname, 'reports', 'q3.pdf'));
});

File Uploads with Multer

npm install multer

const multer = require('multer');

const storage = multer.diskStorage({
  destination: (req, file, cb) => cb(null, 'uploads/'),
  filename: (req, file, cb) => {
    const ext = path.extname(file.originalname);
    cb(null, Date.now() + '-' + Math.random().toString(36).slice(2) + ext);
  }
});

const upload = multer({
  storage,
  limits: { fileSize: 5 * 1024 * 1024 },
  fileFilter: (req, file, cb) => {
    const allowed = ['image/jpeg', 'image/png', 'image/webp'];
    cb(null, allowed.includes(file.mimetype));
  }
});

app.post('/upload', upload.single('avatar'), (req, res) => {
  if (!req.file) return res.status(400).json({ error: 'No file uploaded' });
  res.json({ path: req.file.path, size: req.file.size });
});