How do I properly update my Postgres Database in Node.js? - node.js

Question

The Problem: syntax error at or near "$"
The Context: My App does two CRUD operations - Update & Read Data from a Postgres database. It successfully reads data from the database and displays on the frontend. However, it fails to update the database when I query it to do so. It throws an error that 'syntax error at or near "$"'.
So far, I have failed to debug the error successfully.
The Stacks: Postgres, Node.js, React
The Query (BackEnd):
//burrow a book
app.post("/books/:id", async (req, res) => {
try {
const { id } = req.params;
const copies = await pool.query('SELECT copies FROM books WHERE book_id = $id', [id]);
const stock = copies - 1;
const updateBook = await pool.query("UPDATE books SET copies = $1 WHERE book_id = $2", [stock, id]);
const allBooks = await pool.query("SELECT * FROM books");
res.json(allBooks.rows);
} catch (err) {
console.error(err.message);
}
});
The Function(FrontEnd):
async function burrowbook(id) {
try {
const res = await fetch(`http://localhost:5000/books/${id}` , {method: "POST"});
console.log(res);
// setbooks(jsonData);
// console.log(jsonData);
} catch (err) {
console.error(err.message);
}
}
The Full React Component(FrontEnd):
import React, { Fragment, useEffect, useState } from 'react';
const ListBooks = () => {
const [books, setbooks] = useState([]);
async function burrowbook(id) {
try {
const res = await fetch(`http://localhost:5000/books/${id}` , {method: "POST"});
console.log(res);
// setbooks(jsonData);
// console.log(jsonData);
} catch (err) {
console.error(err.message);
}
}
const getBooks = async () => {
try {
const response = await fetch("http://localhost:5000/books");
const jsonData = await response.json();
setbooks(jsonData);
// console.log(jsonData);
} catch (err) {
console.error(err.message);
}
}
useEffect(() => {
getBooks();
}, []);
return (<Fragment>
<div class="container ">
<h1 class="text-center mt-5">Wakanda Library</h1>
</div>
<table class="table table-hover table-dark text-center mt-5">
<thead>
<tr>
<th scope="col">Book ID</th>
<th scope="col">Title</th>
<th scope="col">Author</th>
<th scope="col">Year</th>
<th scope="col">Stock</th>
<th scope="col">Burrow</th>
<th scope="col">Return</th>
</tr>
</thead>
<tbody>
{books.map(book => (
<tr key={book.book_id}>
<td>{book.book_id} </td>
<td>{book.title} </td>
<td>{book.author} </td>
<td>{book.publish_year} </td>
<td>{book.copies} </td>
<td><button
className="btn btn-success btn-circle btn-md"
onClick={() => burrowbook(book.book_id)}
>
Burrow
</button></td>
<td><button
className="btn btn-primary btn-circle btn-md"
// onClick={() => returnBook(book.book_id)}
>
Return
</button></td>
</tr>
))}
</tbody>
</table>
</Fragment>);
};
export default ListBooks;
The Full index.js script(BackEnd):
const express = require("express");
const app = express();
const cors = require('cors');
const pool = require('./db');
//middleware
app.use(cors());
app.use(express.json()); //req.body
//ROUTES//
//login user
//register user
//list of books in library
app.get("/books", async (req, res) => {
try {
const allBooks = await pool.query("SELECT * FROM books");
res.json(allBooks.rows);
} catch (err) {
console.error(err.message);
}
});
//burrow a book
app.post("/books/:id", async (req, res) => {
try {
const { id } = req.params;
console.log(id);
const copies = await pool.query('SELECT copies FROM books WHERE book_id = $id', [id]);
console.log("b");
const stock = copies - 1;
console.log("c")
const updateBook = await pool.query("UPDATE books SET copies = $1 WHERE book_id = $2", [stock, id]);
console.log("d")
const allBooks = await pool.query("SELECT * FROM books");
console.log("heee")
res.json(allBooks.rows);
} catch (err) {
console.error(err.message);
}
});
//return a book
app.put("/booksreturn/:id", async (req, res) => {
try {
const { id } = req.params;
const { copies } = req.body;
const returnBook = await pool.query(
"UPDATE books SET copies = $copies WHERE book_id = $id",
[copies = parseFloat(copies) + 1, id]
);
res.json("Book was returned!");
} catch (err) {
console.error(err.message);
}
});
//list of books in users possession
app.listen(5000, () => {
console.log("Baba... server don start on top port 5000.")
});