Convert string to number mongodb

Converts a value to an integer. If the value cannot be converted to an integer, $toInt errors. If the value is null or missing, $toInt returns null.

$toInt has the following syntax:

The $toInt takes any valid expression.

The $toInt is a shorthand for the following $convert expression:

{ $convert: { input: , to: "int" } }

Tip

See also:

The following table lists the input types that can be converted to an integer:

Input Type

Behavior

The following table lists some conversion to integer examples:

Example

Results

Create a collection orders with the following documents:

db.orders.insertMany[ [
   { _id: 1, item: "apple", qty: "5", price: 10 },
   { _id: 2, item: "pie", qty: "10", price: NumberDecimal["20.0"] },
   { _id: 3, item: "ice cream", qty: "2", price: "4.99" },
   { _id: 4, item: "almonds" ,  qty: "5", price: 5 }
] ]

The following aggregation operation:

• converts qty to an integer,

• converts price to a decimal,

• calculates the total price:

// Define stage to add convertedPrice and convertedQty fields with the converted price and qty values
priceQtyConversionStage = {
   $addFields: {
      convertedPrice: { $toDecimal: "$price" },
      convertedQty: { $toInt: "$qty" },
   }
};
// Define stage to calculate total price by multiplying convertedPrice and convertedQty fields
totalPriceCalculationStage = {
   $project: { item: 1, totalPrice: { $multiply: [ "$convertedPrice", "$convertedQty" ] } }
};
db.orders.aggregate[ [
   priceQtyConversionStage,
   totalPriceCalculationStage
] ]

The operation returns the following documents:

{ _id: 1, item: 'apple', totalPrice: Decimal128["50"] },
{ _id: 2, item: 'pie', totalPrice: Decimal128["200.0"] },
{ _id: 3, item: 'ice cream', totalPrice: Decimal128["9.98"] },
{ _id: 4, item: 'almonds', totalPrice: Decimal128["25"] }

Note

If the conversion operation encounters an error, the aggregation operation stops and throws an error. To override this behavior, use $convert instead.