适用对象：
MongoDB vCore
如果输入表达式是数字类型 （Decimal、Long、Int 或 Double），则 $isNumber 运算符返回 true。 对于任何其他类型的表达式，运算符 $isNumber 返回 false。
语法
运算符的 $isNumber 语法为：
{ "$isNumber": <expression> }
参数
| 参数 | DESCRIPTION |
|---|---|
expression |
"用于检查是否为数字的指定值" |
例子
请查看 StoreData 数据库中 stores 集合的这个示例文档。
{
"_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
}
]
}
]
}
示例 1：检查双精度值是否为数字
db.stores.aggregate([
{
"$match": {
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d"
}
},
{
"$project": {
"originalLatitude": "$location.lat",
"latitudeIsNumber": {
"$isNumber": "$location.lat"
}
}
}])
此查询返回以下结果：
{
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d",
"originalLatitude": 72.8377,
"latitudeIsNumber": true
}
示例 2：检查 Int 值是否为数字
db.stores.aggregate([
{
"$match": {
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d"
}
},
{
"$project": {
"originalTotalSales": "$sales.totalSales",
"totalSalesIsNumber": {
"$isNumber": "$sales.totalSales"
}
}
}])
此查询返回以下结果：
{
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d",
"originalTotalSales": 9366,
"totalSalesIsNumber": true
}
示例 3：检查字符串是否为数字
db.stores.aggregate([
{
"$match": {
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d"
}
},
{
"$project": {
"idIsNumber": {
"$isNumber": "$_id"
}
}
}])
此查询返回以下结果：
{
"_id": "b0107631-9370-4acd-aafa-8ac3511e623d",
"idIsNumber": false
}