$strLenCP (aggregation)
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Definition
$strLenCP
New in version 3.4.
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.ExampleResults{ $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 } ]