$strLenCP (expression operator)

Definition

$strLenCP

Returns the number of UTF-8 code points in the specified string.

$strLenCP has the following operator expression syntax:

{ $strLenCP: <string expression> }

The argument can be any valid expression that resolves to a string.

If the argument resolves to a value of null or refers to a missing field, $strLenCP returns an error.

Example	Results
`{ $strLenCP: "abcde" }`	`5`
`{ $strLenCP: "Hello World!" }`	`12`
`{ $strLenCP: "cafeteria" }`	`9`
`{ $strLenCP: "cafétéria" }`	`9`
`{ $strLenCP: "" }`	`0`
`{ $strLenCP: "$€λA" }`	`4`
`{ $strLenCP: "寿司" }`	`2`

Behavior

The $strLenCP operator counts the number of code points in the specified string. This behavior differs from the $strLenBytes operator that counts the number of bytes in the string, where each character uses between one and four bytes.

Example

Single-Byte and Multibyte Character Set

Create a food collection:

db.food.insertMany( [   { _id: 1, name: "apple" },   { _id: 2, name: "banana" },   { _id: 3, name: "éclair" },   { _id: 4, name: "hamburger" },   { _id: 5, name: "jalapeño" },   { _id: 6, name: "pizza" },   { _id: 7, name: "tacos" },   { _id: 8, name: "寿司" }] )

The following example uses the $strLenCP operator to calculate the length of each name value:

db.food.aggregate( [   {      $project: {         name: 1,         length: { $strLenCP: "$name" }      }   }] )

Example output:

[   { _id: 1, name: 'apple', length: 5 },   { _id: 2, name: 'banana', length: 6 },   { _id: 3, name: 'éclair', length: 6 },   { _id: 4, name: 'hamburger', length: 9 },   { _id: 5, name: 'jalapeño', length: 8 },   { _id: 6, name: 'pizza', length: 5 },   { _id: 7, name: 'tacos', length: 5 },   { _id: 8, name: '寿司', length: 2 }]

Tip