$convert
The $convert operator converts an expression into the specified type
$convert
The $convert operator converts an expression into a value of the specified type.
Syntax
{
$convert: {
input: < expression > ,
to: < type > ,
format: < binData format > ,
onError: < value to return on error > ,
onNull: < value to return on null >
}
}Parameters
| Parameter | Description |
|---|---|
input | The input value to be converted to the specified type |
to | The type to convert the input value into |
format | (Optional) The binData format of the input or output when converting a value to or from binData |
onError | (Optional) The value to return when the conversion of the input to the specified type fails |
onNull | (Optional) The value to return when the input value to be converted to the specified type is null or missing |
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: Convert an Int value into a String
To convert the fullTime field from an integer to a string, run a query using the $convert operator to make the conversion.
db.stores.aggregate([{
$match: {
_id: "b0107631-9370-4acd-aafa-8ac3511e623d"
}
}, {
$project: {
fulltimeStaff: "$staff.totalStaff.fullTime",
fulltimeStaffAsString: {
$convert: {
input: "$staff.totalStaff.fullTime",
to: "string"
}
}
}
}])This query returns the following result:
[
{
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d",
"fulltimeStaff": 3,
"fulltimeStaffAsString": "3"
}
]Example 2: Convert an Int value into a Boolean value
To convert the fullTime field from an integer to a boolean, run a query using the $convert operator to make the conversion. Any positive value for the fullTime field will be converted to true.
db.stores.aggregate([{
$match: {
_id: "b0107631-9370-4acd-aafa-8ac3511e623d"
}
}, {
$project: {
fulltimeStaff: "$staff.totalStaff.fullTime",
fulltimeStaffAsBool: {
$convert: {
input: "$staff.totalStaff.fullTime",
to: "bool"
}
}
}
}])This query returns the following result:
[
{
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d",
"fulltimeStaff": 3,
"fulltimeStaffAsBool": true
}
]Example 3: Convert an Int value into a Decimal value
To convert the fullTime staff field from an integer to a decimal value, run a query using the $convert operator to make the conversion.
db.stores.aggregate([{
$match: {
_id: "b0107631-9370-4acd-aafa-8ac3511e623d"
}
}, {
$project: {
fulltimeStaff: "$staff.totalStaff.fullTime",
fulltimeStaffAsDecimal: {
$convert: {
input: "$staff.totalStaff.fullTime",
to: "decimal"
}
}
}
}])This query returns the following result:
[
{
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d",
"fulltimeStaff": 3,
"fulltimeStaffAsDecimal": "Decimal128('3')"
}
]