MongoDB $floor Operator

MongoDB provides different types of arithmetic expression operators that are used in the aggregation pipeline stages and $floor operator is one of them. This operator is used to find the largest integer less than or equal to the specified number.

Syntax: 

{ $floor: <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 $floor operator:

In this example, we are going to find the largest integer less than or equal to the value of the perfoPoint field in the development department.

db.employee.aggregate([{$match: {department: "Development"}},
... {$project: {perfoPoint: 1, 
      floorPoint: {$floor: "$perfoPoint"}}}])

Using $floor operator in the embedded document: 

In this example, we are going to find the largest integer less than or equal to the value of the details.perfoPoint field in the HR department.

db.employee.aggregate([{$match: {department: "HR"}},
... {$project: {"details.perfoPoint": 1,
      floorPoint: {$floor: "$details.perfoPoint"}}}])