UPDATED WITH FIX: Is there a way to loop an object and save/update a mongodb document on each iteration without getting ParallelSaveError? - mongodb

Question

I want to update the mongodb document on every loop but seems not to work. I used map to loop through the object and was getting a
parallelSaveError: Can't save() the same doc multiple times in parallel
So now using async.each to loop through the object but seems mongoose only save once. Code below
const openTrade = await TradeModel.find({
$and: [{ isOpen: true }, { price: { $lte: price } }]
})
.sort("volume")
.where({ userId: { $ne: req.authUser._id } });
trade = async openTrade => {
const buyerInfo = await UserModel.findById(req.authUser._id);
const buyerWallet = await WalletModel.findById(buyerInfo.walletId);
const sellerInfo = await UserModel.findById(openTrade.userId);
const sellerWallet = await WalletModel.findById(sellerInfo.walletId);
buyerWallet.balance = parseInt(buyerWallet.balance) - amountToPay;
sellerWallet.balance = parseInt(sellerWallet.balance) + amountToPay;
await Promise.all([sellerWallet.save(), buyerWallet.save()]);
};
async.forEachOf(openTrade, trade);
So I finally found the issue. I did not make the buyerInfo, sellerInfo and Wallets variable constant. So now it works. Thanks

Answer 1

You can try as below: As according to MongoDB update If the document contains an _id field, then the save() method is equivalent to an update with the upsert option set to true and the query predicate on the _id field.
const openTrade = await TradeModel.find({$and:[{isOpen : true}, {price : {$lte : price}}]}).sort('volume').where({userId : {$ne : req.authUser._id } })
trade = async (openTrade)=>{
buyerInfo = await UserModel.findById(req.authUser._id)
buyerWallet = await WalletModel.findById(buyerInfo.walletId)
sellerInfo = await UserModel.findById(openTrade.userId)
sellerWallet = await WalletModel.findById(sellerInfo.walletId)
delete buyerWallet._id;
delete sellerWallet._id;
buyerWallet.balance = parseInt(buyerWallet.balance) - amountToPay
sellerWallet.balance = parseInt(sellerWallet.balance) + amountToPay
await Promise.all([sellerWallet.save(), buyerWallet.save()])
}
async.forEachOf(openTrade, trade)