Question:

How to delete documents from a mongoDB collection without an error?

Problem:

I have an inventory management system app that uses React for the front end, express for the backend, and mongoDB. I have a table of products and next to each product there is a delete button. When I click the delete button I want to delete that product from my mongoDB database.

I set up an endpoint in express, and I am passing the correct id for each product, but I keep getting an 500 error. here is the frontend code where the delete button is handled:

import React, { Component } from 'react'

class ProductRow extends Component {

constructor(props) {

super(props)

this.destroy = this.destroy.bind(this)

}

async destroy() {

try {

const productid = this.props.productid

const response = await fetch(`http://localhost:5000/product/delete/${productid}`, {

method: 'DELETE'

});

if (!response.ok) {

throw new Error('Failed to delete product');

}

// Remove the deleted product from the state

const updatedProducts = this.state.products.filter(product => product.id !== productid);

this.setState({ products: updatedProducts });

} catch (error) {

console.error('Error deleting product:', error);

}

render () {

return (

<tr>

<td>{this.props.product.name}</td>

<td>{this.props.product.category}</td>

<td>{this.props.product.price}</td>

<td>{this.props.product.instock.toString()}</td>

<td class="text-right"><button onClick={this.destroy} class="btn btn-info">Delete</button></td>

</tr>

)

}

export default ProductRow

here is the express server code:

var express = require('express')

var bodyParser = require('body-parser')

var app = express()

const cors = require("cors");

app.use(bodyParser.json());

app.use(cors());

var mongoose = require('mongoose')

var dbURL = 'mongodb+srv://mario:tech@nodeproject.azbwi6o.mongodb.net/?retryWrites=true&w=majority'

try {

mongoose.connect(dbURL)

console.log('Mongo connected')

}

catch(error) {

console.log(error)

}

// Create a mongoose model

var Product = mongoose.model('Product', {

"id": Number,

"product": {

"productid": Number,

"category": String,

"price": Number,

"name": String,

"instock": Boolean

}

});

// Endpoint to fetch products

app.get('/product/get/', async (req, res) => {

try {

// Fetch products from the database using Mongoose

const products = await Product.find({});

res.json(products); // Send products as a JSON response

} catch (error) {

res.status(500).json({ message: error.message });

}

});

// Endpoint to handle POST request for creating a product

app.post('/product/create', async (req, res) => {

try {

const {id, name, category, price } = req.body;

const productData = {

id: id,

product: {

productid: id,

category: category,

price: price,

name: name,

instock: true

}

};

const newProduct = new Product(productData);

const savedProduct = await newProduct.save();

res.status(201).json(savedProduct);

} catch (error) {

res.status(500).json({ message: error.message });

}

});

// Endpoint to delete a product by its ID

app.delete('/product/delete/:id', async (req, res) => {

const productId = req.params.id;

try {

const documentToDelete = { _id: `ObjectID(${productId})` };

const deletedProduct = await Product.deleteOne(documentToDelete);

if (!deletedProduct) {

return res.status(404).json({ message: 'Product not found' });

}

res.json({ message: 'Product deleted successfully' });

} catch (error) {

res.status(500).json({ message: error.message });

}

});

var server = app.listen(5000, () => {

console.log('server is listening on port', server.address().port)

})

I believe the error is from this line: const deletedProduct = await Product.deleteOne(documentToDelete); this is the value of documentToDelete: { _id: 'ObjectID(657142d6ad5a5e69a000758d)' } Could I not be using the deleteOne method correctly?

I tried fixing it myself, by looking at other examples and the official MongoDB documentation

Solution:

Try this code to resolve the error you are facing :

app.delete('/product/delete/:id', async (req, res) => {

const productId = req.params.id;

try {

if (!mongoose.Types.ObjectId.isValid(productId)) {

return res.status(400).json({ message: 'Invalid product id' });

}

const deletedProduct = await Product.deleteOne({ _id: productId });

if (deletedProduct.deletedCount == 0) {

return res.status(404).json({ message: 'Product not found' });