如何使用 mongoose 在 nodejs 中转换日期格式

Question

I have a document like this

{
            "_id": "5c2326cb5d558f6693577119",
            "date": "08/02/16 00:00",
            "symbol": "WLTW",
            "open": "113.300003",
            "close": 111.160004,
            "low": 110.459999,
            "high": 113.300003,
            "volume": 1200500,
            "createdAt": "2018-12-26T06:59:23.901Z",
            "updatedAt": "2018-12-26T06:59:23.901Z"
        }

I am doing a query something like this

const getStockBySymbol = (data) => {
    console.log('Hitting Stock Model fine!!')
    return Stock.find({symbol: data})
        .then((stocks) => {
            console.log(stocks)
            if (stocks) { return stocks }
        })
}

I need to convert the date format to Year-month-date format

So current format is dd\\mm\\yy in date property I want to convert that to yyyy-mm-dd

I am new with MongoDB would be great if anyone could help

Thanks

Answer 1

you need to map results after fetching your data :

const getStockBySymbol = (data) => {
    return Stock.find({symbol: data})
        .then((stocks) => {
            if (stocks) { 
            var newStocks=stocks.map(function(stock){
             let formattedDate=moment(stock.date,"dd/mm/YY hh:mm").format("YYYY-mm-dd");
             stock.date=formattedDate;
             return stock;
            });
            return newStocks;
            }
        })
}

Answer 2

You're best option here would be to use momentjs library. It's a no-brainer solution for time format conversion :

moment(new Date(date)).format('YYYY-MM-DD');

This should yield '2016-08-02'.

Answer 3

You can parse string to ISODate using $dateFromString operator. The problem is that all formats for year expect four digits so it will parse your year to 0016 instead of expected 2016 . To fix that you can use $dateToParts and $dateFromParts and manually add 2000 . Then you can use $dateToString to convert it to your format, try:

Stockdb.aggregate([
    {
        $match: { symbol: "WLTW" }
    },
    {
        $addFields: {
            date: {
                $dateToParts: {
                    date: { $dateFromString: { dateString: "$date", format: "%d/%m/%Y %H:%M" } }
                }
            }
        }
    },
    {
        $addFields: {
            date: {
                $dateToString: {
                    date: {
                        $dateFromParts: {
                            day: "$date.day",
                            month: "$date.month",
                            year: { $add: [ 2000, "$date.year" ] }
                        }
                    },
                    format: "%Y-%m-%d"
                }
            }
        }
    }
])

$addFields overwrites existing fields in this case

EDIT: for lower MongoDB versions you can use $substr and $concat operators assuming your date has fixed length:

Stockdb.aggregate([
    {
        $match: { symbol: "WLTW" }
    },
    {
        $addFields: {
            date: {
                $concat: [
                    '20',
                    { $substr: [ "$date", 6, 2 ] },
                    '-',
                    { $substr: [ "$date", 3, 2 ] },
                    '-',
                    { $substr: [ "$date", 0, 2 ] },
                ]
            }
        }
    }
])