$dateFromParts

The $dateFromParts operator constructs a date from individual components such as year, month, day, hour, minute, second, and millisecond. This operator can be useful when dealing with data that stores date components separately.

Syntax

{
    $dateFromParts: {
        year: < year > ,
        month: < month > ,
        day: < day > ,
        hour: < hour > ,
        minute: < minute > ,
        second: < second > ,
        millisecond: < millisecond > ,
        timezone: < timezone >
    }
}

Parameters

Parameter Description
year The year component of the date.
month The month component of the date.
day The day component of the date.
hour The hour component of the date.
minute The minute component of the date.
second The second component of the date.
millisecond The millisecond component of the date.
timezone Optional. A timezone specification.

Examples

Consider this sample document from the stores collection.

{
    "_id": "0fcc0bf0-ed18-4ab8-b558-9848e18058f4",
    "name": "First Up Consultants | Beverage Shop - Satterfieldmouth",
    "location": {
        "lat": -89.2384,
        "lon": -46.4012
    },
    "staff": {
        "totalStaff": {
            "fullTime": 8,
            "partTime": 20
        }
    },
    "sales": {
        "totalSales": 75670,
        "salesByCategory": [
            {
                "categoryName": "Wine Accessories",
                "totalSales": 34440
            },
            {
                "categoryName": "Bitters",
                "totalSales": 39496
            },
            {
                "categoryName": "Rum",
                "totalSales": 1734
            }
        ]
    },
    "promotionEvents": [
        {
            "eventName": "Unbeatable Bargain Bash",
            "promotionalDates": {
                "startDate": {
                    "Year": 2024,
                    "Month": 6,
                    "Day": 23
                },
                "endDate": {
                    "Year": 2024,
                    "Month": 7,
                    "Day": 2
                }
            },
            "discounts": [
                {
                    "categoryName": "Whiskey",
                    "discountPercentage": 7
                },
                {
                    "categoryName": "Bitters",
                    "discountPercentage": 15
                },
                {
                    "categoryName": "Brandy",
                    "discountPercentage": 8
                },
                {
                    "categoryName": "Sports Drinks",
                    "discountPercentage": 22
                },
                {
                    "categoryName": "Vodka",
                    "discountPercentage": 19
                }
            ]
        },
        {
            "eventName": "Steal of a Deal Days",
            "promotionalDates": {
                "startDate": {
                    "Year": 2024,
                    "Month": 9,
                    "Day": 21
                },
                "endDate": {
                    "Year": 2024,
                    "Month": 9,
                    "Day": 29
                }
            },
            "discounts": [
                {
                    "categoryName": "Organic Wine",
                    "discountPercentage": 19
                },
                {
                    "categoryName": "White Wine",
                    "discountPercentage": 20
                },
                {
                    "categoryName": "Sparkling Wine",
                    "discountPercentage": 19
                },
                {
                    "categoryName": "Whiskey",
                    "discountPercentage": 17
                },
                {
                    "categoryName": "Vodka",
                    "discountPercentage": 23
                }
            ]
        }
    ]
}

Example 1: Constructing a start date

This query constructs precise startDate and endDate values from nested fields using $dateFromParts, then calculates the event duration in days. It helps standardize and analyze event timelines stored in fragmented date formats.

db.stores.aggregate([
  { 
    $match: { _id: "e6410bb3-843d-4fa6-8c70-7472925f6d0a" } 
  },
  { 
    $unwind: "$promotionEvents" 
  },
  {
    $project: {
      _id: 1,
      startDate: {
        $dateFromParts: {
          year: "$promotionEvents.promotionalDates.startDate.Year",
          month: "$promotionEvents.promotionalDates.startDate.Month",
          day: "$promotionEvents.promotionalDates.startDate.Day"
        }
      }
    }
  }
])

This query returns the following result.

[
  {
    "_id": "e6410bb3-843d-4fa6-8c70-7472925f6d0a",
    "startDate": "2024-09-21T00:00:00.000Z"
  }
]

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