nodejs server

const express = require('express');
const multer = require('multer');
const path = require('path');
const mongoose = require('mongoose');

// Set up the MongoDB connection
mongoose.connect('mongodb://localhost/file_upload', { useNewUrlParser: true, useUnifiedTopology: true });
const db = mongoose.connection;
db.on('error', console.error.bind(console, 'MongoDB connection error:'));
db.once('open', () => {
  console.log('Connected to MongoDB');
});

// Create a schema for the uploaded files
const fileSchema = new mongoose.Schema({
  filename: String,
  originalname: String,
  mimetype: String,
  size: Number,
  uploadDate: { type: Date, default: Date.now }
});

const File = mongoose.model('File', fileSchema);

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

// Create multer instance
const upload = multer({ storage });

// Create Express app
const app = express();

// Serve static files from the "public" directory
app.use(express.static('public'));

// Route for the file upload form
app.get('/', (req, res) => {
  res.sendFile(path.join(__dirname, 'public', 'index.html'));
});

// Route for handling file upload
app.post('/upload', upload.single('file'), async (req, res) => {
  if (req.file) {
    const uploadedFile = new File({
      filename: req.file.filename,
      originalname: req.file.originalname,
      mimetype: req.file.mimetype,
      size: req.file.size
    });

    try {
      await uploadedFile.save();
      res.send('File uploaded successfully!');
    } catch (error) {
      res.status(500).send('Error saving file to database.');
    }
  } else {
    res.status(400).send('No file uploaded.');
  }
});

// Route for retrieving all uploaded files
app.get('/files', async (req, res) => {
  try {
    const files = await File.find().sort('-uploadDate');
    res.json(files);
  } catch (error) {
    res.status(500).send('Error retrieving files from database.');
  }
});

// Route for retrieving a specific uploaded file
app.get('/files/:id', async (req, res) => {
  try {
    const file = await File.findById(req.params.id);
    res.json(file);
  } catch (error) {
    res.status(500).send('Error retrieving file from database.');
  }
});

// Route for deleting a specific uploaded file
app.delete('/files/:id', async (req, res) => {
  try {
    const file = await File.findByIdAndDelete(req.params.id);
    res.send('File deleted successfully!');
  } catch (error) {
    res.status(500).send('Error deleting file from database.');
  }
});

// Route for updating a specific uploaded file
app.put('/files/:id', async (req, res) => {
  try {
    const fileId = req.params.id;
    const { filename, originalname, mimetype, size } = req.body;

    const updatedFile = await File.findByIdAndUpdate(fileId, {
      filename,
      originalname,
      mimetype,
      size
    });

    if (updatedFile) {
      res.send('File updated successfully!');
    } else {
      res.status(404).send('File not found.');
    }
  } catch (error) {
    res.status(500).send('Error updating file.');
  }
});

// Start the server
const port = 3000;
app.listen(port, () => {
  console.log(`Server is listening on port ${port}`);
});


<!DOCTYPE html>
<html>
  <head>
    <title>File Upload Form</title>
  </head>
  <body>
    <h1>File Upload</h1>
    <form action="/upload" method="post" enctype="multipart/form-data">
      <input type="file" name="file" />
      <input type="submit" value="Upload" />
    </form>

    <h1>Uploaded Files</h1>
    <ul id="fileList"></ul>

    <script>
      // Fetch uploaded files and display them in the list
      fetch('/files')
        .then((response) => response.json())
        .then((data) => {
          const fileList = document.getElementById('fileList');
          data.forEach((file) => {
            const listItem = document.createElement('li');
            listItem.textContent = file.originalname;
            fileList.appendChild(listItem);
          });
        });
    </script>
  </body>
</html>