如何优化nodejs中的mongodb查询？

Question

I have a code that is running in nodejs in which I have to call the MongoDB query which has some aggregation property and I have called using callbacks but the main issue is that it doesn't be working as I expected. like I want to run the code async but it does not work like that I want that once the MongoDB query is finished then my another function will be called up but currently my another function called up in between the code execution, I am very upset with this approach, I need help please give a solution. here is the code.

        function (done) {
            var count = 0;
            Wine.distinct("_id", {}).exec(function(err,winesList){
                for(var x=0;x < 100;x++){
                    var currentWineId = winesList[x].toString();
                    //wineId should not be object
                    WTHelper.calculateAvgWinePriceAndUpdate(currentWineId, todayDate,'true', function (err, result) {
                        count++;
                        console.log("statusReport.totalCount :", count);
                    })
                } done(null, count);
            })
        }, function (count) {
            console.log("prateek totalCount :", count);
        }
    ])

     //Gets the avergae price of the last 4 Months of the wine
     var totalCount=0;
    purchase_date = getDayEndDate(purchase_date);
    var threeMonthsOldDate = new Date(purchase_date);
    threeMonthsOldDate.setMonth(threeMonthsOldDate.getMonth() - 3);
    var startDate = getDayStartDate(threeMonthsOldDate);
    var purchaseDateString = new Date(
        getDayStartDate(purchase_date)
    ).toDateString();
    console.log(
        "calculateAvgWinePriceAndUpdate: starting date :" +
        startDate +
        " purchase_date: ",
        purchase_date
    );

    console.log(
        "calculateAvgWinePriceAndUpdate: purchaseDateString",
        purchaseDateString
    );
    Transaction.aggregate(
        [
            {
                $match: {
                    transaction_type: "Cr",
                    reason: {
                        $nin: ["Edited", "Deleted"],
                    },
                },
            },
            {
                $unwind: "$details",
            },
            {
                $match: {
                    wine_id: wineId,
                    transaction_type: "Cr",
                    "details.price": {
                        $gt: 0,
                    },
                    purchase_date: {
                       // $gte: startDate,
                        $lte: purchase_date,
                    },
                },
            },
            {
                $group: {
                    _id: {
                        wine_id: "$wine_id",
                    },
                    total_price: {
                        $sum: {
                            $multiply: ["$details.qty", "$details.price_usd"],
                        },
                    },
                    total_qty: {
                        $sum: "$details.qty",
                    },
                },
            },
            {
                $sort: {
                    purchase_date: -1,
                },
            },
            {
                $limit: 50,
            },
            {
                $project: {
                    _id: 0,
                    wine_id: "$_id.wine_id",
                    total_price: "$total_price",
                    total_qty: "$total_qty",
                },
            },
        ],
        function (err, avgWinePriceData) {
            console.log(
                "calculateAvgWinePriceAndUpdate: Aggregate Result:",
                avgWinePriceData
            );
            var purchase_date_price = 0;
            var purchase_date_quantity = 0;

            if (avgWinePriceData.length) {
                // There are transactions
                var purchase_date_price = avgWinePriceData[0].total_price;
                var purchase_date_quantity = avgWinePriceData[0].total_qty;

                console.log(
                    "calculateAvgWinePriceAndUpdate: purchase_date_price ",
                    purchase_date_price
                );
                console.log(
                    "calculateAvgWinePriceAndUpdate: purchase_date_quantity",
                    purchase_date_quantity
                );
                //New Avg. Wine Price.
                var avgWinePrice = parseFloat(
                    purchase_date_price / purchase_date_quantity
                );
                if (isNaN(avgWinePrice)) {
                    avgWinePrice = 0;
                }
                console.log(
                    "calculateAvgWinePriceAndUpdate: Avg. Price for Purchase Date:",
                    avgWinePrice
                );
                console.log(
                    "calculateAvgWinePriceAndUpdate: Purchase Date:",
                    purchaseDateString
                );
                WinePrice.findOne(
                    {
                        wine_id: mongoose.Types.ObjectId(wineId),
                        price_date_string: purchaseDateString,
                    },
                    function (err, winePrice) {
                        //console.log('calculateAvgWinePriceAndUpdate: wine price object ',winePrice)
                     
                        if (winePrice) {
                            winePrice.purchase_date = new Date(purchase_date);
                            winePrice.price = avgWinePrice;
                            winePrice.quantity = purchase_date_quantity;
                        } else {
                            var winePrice = new WinePrice();
                            winePrice.historic_price = {};
                            winePrice.wine_id = mongoose.Types.ObjectId(wineId);
                            winePrice.price = avgWinePrice;
                            winePrice.price_date = new Date(purchase_date);
                            winePrice.price_date_string = purchaseDateString;
                            winePrice.purchase_date = new Date(purchase_date);
                            winePrice.quantity = purchase_date_quantity;
                        }

                        winePrice.save(function (err) {
                            if (err) {
                                console.log(
                                    "calculateAvgWinePriceAndUpdate: Error Saving Wine Price",
                                    err
                                );
                            } else {
                                console.log(
                                    "calculateAvgWinePriceAndUpdate: Price Updated for Purchase Date",purchaseDateString
                                );
                                 if (check == 'true') {
                                    totalCount++
                                    mainCallback(err, totalCount);
                                }
                            }
                        });
                     
                    });
            }
        }
    );
};

Check the output

statusReport.totalCount : 98
calculateAvgWinePriceAndUpdate: Price Updated for Purchase Date Sat Sep 12 2020
statusReport.totalCount : 99
calculateAvgWinePriceAndUpdate: Price Updated for Purchase Date Sat Sep 12 2020
statusReport.totalCount : 100
calculateAvgWinePriceAndUpdate: Price Updated for Purchase Date Sat Sep 12 2020

Second function is missing at the bottom

Answer 1

If you queries are not inter-related the you use promise.all which will parallel execute your queries.

Or they are inter-related or you you want to execute one after another then you can use the async-await approach will execute your db call synchronously in async manner.