$strLenCP (aggregation)

定義

$strLenCP

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

$strLenCPには次の演算子式の構文があります。

{ $strLenCP: <string expression> }

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

引数が null 値に解決されるか、欠落しているフィールドを参照する場合、$strLenCP はエラーを返します。

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

動作

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.

例

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" }
] )

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

[
   { _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 }
]