We will update the product controller file to add the decreaseQuantity controller method, which will update the stock quantities of all the products purchased in the new order.
mern-marketplace/server/controllers/product.controller.js:
const decreaseQuantity = (req, res, next) => { let bulkOps = req.body.order.products.map((item) => { return { "updateOne": { "filter": { "_id": item.product._id } , "update": { "$inc": {"quantity": -item.quantity} } } } }) Product.bulkWrite(bulkOps, {}, (err, products) => { if(err){ return res.status(400).json({ error: "Could not update product" }) } next() })}
Since the update operation in this case involves a bulk update of multiple products in the collection after matching ...
