$isoWeek

The $isoWeek operator returns the week number of the year in ISO 8601 format, ranging from 1 to 53. The operator accepts a date expression that resolves to a Date, Timestamp, or ObjectId. In ISO 8601, weeks start on Monday and the first week of the year is the week that contains the first Thursday of the year.

Syntax

{
  $isoWeek: <dateExpression>
}

Parameters

Parameter Description
dateExpression An expression that resolves to a Date, Timestamp, or ObjectId. If the expression resolves to null or is missing, $isoWeek returns null.

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: Get ISO week number for promotion events

This query extracts the ISO week number for promotion event start dates.

db.stores.aggregate([
  { $match: {"_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74"} },
  { $unwind: "$promotionEvents" },
  {
    $project: {
      eventName: "$promotionEvents.eventName",
      startDate: {
        $dateFromParts: {
          year: "$promotionEvents.promotionalDates.startDate.Year",
          month: "$promotionEvents.promotionalDates.startDate.Month",
          day: "$promotionEvents.promotionalDates.startDate.Day"
        }
      }
    }
  },
  {
    $project: {
      eventName: 1,
      startDate: 1,
      isoWeekNumber: { $isoWeek: "$startDate" },
      year: { $year: "$startDate" }
    }
  }
])

This query returns the following results:

[
  {
    "_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74",
    "eventName": "Massive Markdown Mania",
    "startDate": "2023-06-29T00:00:00.000Z",
    "isoWeekNumber": 26,
    "year": 2023
  },
  {
    "_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74",
    "eventName": "Fantastic Deal Days",
    "startDate": "2023-09-27T00:00:00.000Z",
    "isoWeekNumber": 39,
    "year": 2023
  },
  {
    "_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74",
    "eventName": "Discount Delight Days",
    "startDate": "2023-12-26T00:00:00.000Z",
    "isoWeekNumber": 52,
    "year": 2023
  },
  {
    "_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74",
    "eventName": "Super Sale Spectacular",
    "startDate": "2024-03-25T00:00:00.000Z",
    "isoWeekNumber": 13,
    "year": 2024
  },
  {
    "_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74",
    "eventName": "Grand Deal Days",
    "startDate": "2024-06-23T00:00:00.000Z",
    "isoWeekNumber": 25,
    "year": 2024
  },
  {
    "_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74",
    "eventName": "Major Bargain Bash",
    "startDate": "2024-09-21T00:00:00.000Z",
    "isoWeekNumber": 38,
    "year": 2024
  }
]

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