index.ts

import express, { Request } from "express";
import orderRepository from "../data";

const itemRouter = express.Router();

itemRouter
	.route("/:id/item")
	.post(async (req: Request<{ id: string }, {}, { product_id: number; quantity: number }, {}>, res) => {
		const { body, params } = req;
		const { product_id, quantity } = body;
		const { id } = params;
		const order = orderRepository.addOrderItem(Number(id), product_id, quantity);

		res.status(200).send(order);
	});

export default itemRouter;