length Function in MongoDB

In MongoDB, you can find the length of a string using the $strLenCP aggregation operator. Here's how you can use it with an example:

Suppose you have a collection named data containing documents with a field named text, and you want to find the length of the text field:

db.data.aggregate([

  {

    $project: {

      text: 1,

      text_length: { $strLenCP: "$text" }

    }

  }

])

In this example:

- The $project stage is used to include the text field in the output and to add a new field text_length.

- The $strLenCP operator is applied to the text field to compute the length of the string.

This will return documents with the original text field and an additional text_length field containing the length of each string.

Keep in mind that $strLenCP returns the length of the string in UTF-8 code points, not in bytes. This is important because characters that are represented using multiple bytes in UTF-8 will have a length greater than 1.

Here's an example document from the output:

json

{

  "text": "Hello World",

  "text_length": 11

}

This demonstrates how to find the length of a string in MongoDB using the $strLenCP operator.