尝试在“已购买”之后从网页中删除项目，但仍显示在用户已购买项目的历史记录中

const express = require('express');
const mongoose = require('mongoose');
const app = express();

mongoose.connect('mongodb://localhost/mydatabase', { useNewUrlParser: true, useUnifiedTopology: true });

const purchaseSchema = new mongoose.Schema({
  userId: String,
  productId: String,
  date: { type: Date, default: Date.now }
});

const Purchase = mongoose.model('Purchase', purchaseSchema);

app.delete('/api/purchases/:productId', async (req, res) => {
  try {
    await Purchase.deleteOne({ productId: req.params.productId });
    res.status(200).send('Purchase deleted successfully');
  } catch (error) {
    res.status(500).send('Error deleting purchase');
  }
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

const purchases = await Purchase.find({ userId: req.user._id, date: { $lte: new Date() } });