$bitNot (bitwise expression)

APPLIES TO: MongoDB vCore

The $bitNot operator performs a bitwise NOT operation on integer values. It inverts all the bits of the operand, turning 1s into 0s and 0s into 1s. The result is the bitwise complement of the input value.

Syntax

The syntax for the $bitNot operator is as follows:

{
  $bitNot: <expression>
}

Parameters

Description
expression An expression that evaluates to an integer. The $bitNot operator performs a bitwise NOT operation on this value.

Example

Let's understand the usage with sample json from stores dataset.

{
  "_id": "26afb024-53c7-4e94-988c-5eede72277d5",
  "name": "First Up Consultants | Microphone Bazaar - South Lexusland",
  "location": {
    "lat": -29.1866,
    "lon": -112.7858
  },
  "staff": {
    "totalStaff": {
      "fullTime": 14,
      "partTime": 8
    }
  },
  "sales": {
    "totalSales": 83865,
    "salesByCategory": [
      {
        "categoryName": "Lavalier Microphones",
        "totalSales": 44174
      },
      {
        "categoryName": "Wireless Microphones",
        "totalSales": 39691
      }
    ]
  },
  "promotionEvents": [
    {
      "eventName": "Incredible Savings Showcase",
      "promotionalDates": {
        "startDate": {
          "Year": 2024,
          "Month": 9,
          "Day": 21
        },
        "endDate": {
          "Year": 2024,
          "Month": 9,
          "Day": 29
        }
      },
      "discounts": [
        {
          "categoryName": "Condenser Microphones",
          "discountPercentage": 20
        },
        {
          "categoryName": "Microphone Stands",
          "discountPercentage": 17
        }
      ]
    }
  ]
}

Example 1: Basic bitwise NOT operation

Perform a bitwise NOT operation on staff numbers to create inverted flags.

db.stores.aggregate([
  { $match: {"_id": "26afb024-53c7-4e94-988c-5eede72277d5"} },
  {
    $project: {
      name: 1,
      fullTimeStaff: "$staff.totalStaff.fullTime",
      partTimeStaff: "$staff.totalStaff.partTime",
      invertedFullTime: {
        $bitNot: "$staff.totalStaff.fullTime"
      },
      invertedPartTime: {
        $bitNot: "$staff.totalStaff.partTime"
      }
    }
  }
])

This produces the following output:

[
  {
    _id: '26afb024-53c7-4e94-988c-5eede72277d5',
    name: 'First Up Consultants | Microphone Bazaar - South Lexusland',
    fullTimeStaff: 14,
    partTimeStaff: 8,
    invertedFullTime: -15,
    invertedPartTime: -9
  }
]

The bitwise NOT of 14 results in -15, and the bitwise NOT of 8 results in -9. This is due to two's complement representation where ~n = -(n+1).

Example 2: Using $bitNot with Discount Percentages

Apply bitwise NOT operations on discount percentages.

db.stores.aggregate([
  { $match: {"_id": "26afb024-53c7-4e94-988c-5eede72277d5"} },
  { $unwind: "$promotionEvents" },
  { $match: {"promotionEvents.eventName": "Incredible Savings Showcase"} },
  { $unwind: "$promotionEvents.discounts" },
  {
    $project: {
      name: 1,
      eventName: "$promotionEvents.eventName",
      categoryName: "$promotionEvents.discounts.categoryName",
      discountPercentage: "$promotionEvents.discounts.discountPercentage",
      invertedDiscount: {
        $bitNot: "$promotionEvents.discounts.discountPercentage"
      }
    }
  }
])

This produces the following output:

[
  {
    _id: '26afb024-53c7-4e94-988c-5eede72277d5',
    name: 'First Up Consultants | Microphone Bazaar - South Lexusland',
    eventName: 'Incredible Savings Showcase',
    categoryName: 'Condenser Microphones',
    discountPercentage: 20,
    invertedDiscount: -21
  },
  {
    _id: '26afb024-53c7-4e94-988c-5eede72277d5',
    name: 'First Up Consultants | Microphone Bazaar - South Lexusland',
    eventName: 'Incredible Savings Showcase',
    categoryName: 'Microphone Stands',
    discountPercentage: 17,
    invertedDiscount: -18
  }
]

The bitwise NOT operation inverts all bits: 20 becomes -21 and 17 becomes -18.

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