无法使用multer和mongose更新数据库

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

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

const upload = multer({ storage: storage });

const mongoose = require('mongoose');

const userSchema = new mongoose.Schema({
  name: String,
  email: String,
  profilePicture: String
});

const User = mongoose.model('User', userSchema);

const express = require('express');
const router = express.Router();

router.post('/update-profile', upload.single('profilePicture'), async (req, res) => {
  try {
    const { name, email } = req.body;
    const profilePicture = req.file.path;

    const user = await User.findByIdAndUpdate(req.user._id, { name, email, profilePicture }, { new: true });
    res.status(200).json(user);
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
});

const fileFilter = (req, file, cb) => {
  const allowedTypes = ['image/jpeg', 'image/png', 'image/gif'];
  if (allowedTypes.includes(file.mimetype)) {
    cb(null, true);
  } else {
    cb(new Error('Invalid file type'), false);
  }
};

const upload = multer({ storage: storage, fileFilter: fileFilter });

mongoose.connect('mongodb://localhost:27017/mydatabase', {
  useNewUrlParser: true,
  useUnifiedTopology: true,
  useFindAndModify: false,
  useCreateIndex: true
}).then(() => console.log('MongoDB connected'))
  .catch(err => console.log(err));