MongoDB $abs operator
MongoDB provides different types of arithmetic expression operators that are used in the aggregation pipeline stages and $abs operator is one of them. This operator is used to find the absolute value of the specified number.
Syntax:
{ $abs: <number> }
Here, the number is a valid expression until it resolves to a number.
- If the entered value is null, then this operator will return null.
- If the entered value is NaN, then this operator will return NaN.
- If the entered value is a missing field, then this operator will return null.
Examples:
In the following examples, we are working with:
Database: w3wiki
Collection: Employee
Document: three documents that contain the details of the employees in the form of field-value pairs.
Using $abs operator:
In this example, we are going to find the total salary of every employee in the development department.
db.Employee.aggregate([{$match: {department: "Development"}}, ... {$project: {name:1, tSalary: {$abs: {$add: ["$firstSalary", "$secondSalary"]}}}}])
Using $abs operator in embedded documents:
In this example, we are going to find a total of three months’ salary of the employee in the HR department.
db.Employee.aggregate([{$match: {department: "HR"}}, ... {$project: {name: 1, tSalary: {$abs: {$add: ["$salary.firstMonth", "$salary.secondMonth", "$salary.thirdMonth"]}}}}])
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