$add
The $add operator returns the sum of two numbers or the sum of a date and numbers.
$add
The $add operator adds numbers together or adds numbers and dates. When adding numbers and dates, the numbers are interpreted as milliseconds.
Parameters
| Parameter | Description |
|---|---|
<listOfExpressions> | Any valid expressions that resolve to numbers or dates. The expressions can be any combination of numbers and dates. |
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 the current and project staff count
To calculate the total staff and project the total staff looking forward, use the $add operator on the nested totalStaff object to return the desired results.
db.stores.aggregate([{
$match: {
_id: "40d6f4d7-50cd-4929-9a07-0a7a133c2e74"
}
}, {
$project: {
name: 1,
currentTotalStaff: {
$add: ["$staff.totalStaff.fullTime", "$staff.totalStaff.partTime"]
},
projectedNextYearStaff: {
$add: ["$staff.totalStaff.fullTime", "$staff.totalStaff.partTime", 2]
}
}
}])This query returns the following result:
[
{
"_id": "40d6f4d7-50cd-4929-9a07-0a7a133c2e74",
"name": "Proseware, Inc. | Home Entertainment Hub - East Linwoodbury",
"currentTotalStaff": 39,
"projectedNextYearStaff": 41
}
]