Introduction to MongoDB $toInt Operator

MongoDB is a popular NoSQL database that provides multiple operators for better querying and manipulating data. $toInt is one of them, which converts a value to an integer.


The syntax of the $toInt operator is as follows:

{ $toInt: <expression> }

Here, <expression> represents the expression to convert to an integer.

Use Cases

The $toInt operator can be used in many scenarios, such as converting a string to an integer, converting a float to an integer, etc. When performing aggregation operations, it may be necessary to convert the values of certain fields to integers for better grouping and calculation.


Suppose we have a students collection that contains the names and ages of students. The age is stored as a string, and we need to convert it to an integer. Here is an example:

Data Preparation

  { name: "Alice", age: "18" },
  { name: "Bob", age: "20" },
  { name: "Charlie", age: "22" },
  { name: "David", age: "25" }


Now, we can use the $toInt operator to convert the age field to an integer:

db.students.aggregate([{ $project: { name: 1, age: { $toInt: "$age" } } }])

The above code will return the following result:

{ "_id" : ObjectId("..."), "name" : "Alice", "age" : 18 }
{ "_id" : ObjectId("..."), "name" : "Bob", "age" : 20 }
{ "_id" : ObjectId("..."), "name" : "Charlie", "age" : 22 }
{ "_id" : ObjectId("..."), "name" : "David", "age" : 25 }


The $toInt operator is very convenient for quickly converting values to integers for better querying and manipulating data. It is particularly useful in aggregation operations, especially when performing numeric calculations or grouping operations.