$toUUID (aggregation)（聚合）

Definition定义

$toUUID

Converts a string value to a UUID. If the input value is not a string, $toUUID errors.将字符串值转换为UUID。如果输入值不是字符串，则$toUUID错误。

Syntax语法

{
   $toUUID: <expression>
}

The $toUUID expression is shorthand for the following $convert expression:$toUUID表达式是以下$convert表达式的简写：

{
   $convert: {
      input: <expression>,
      to: {
         type: "binData",
         subtype: 4 // UUID
      },
      format: "uuid"
   }
}

Example示例

Create a products collection with the following document:使用以下文档创建products集合：

db.products.insertOne(
   {
      name: "laptop",
      price: 400,
      UUID: "0e3b9063-8abd-4eb3-9f9f-f4c59fd30a60"
   }
)

In the example document, the UUID field is a string. To convert the UUID field to a UUID value, run the following $toUUID operation:在示例文档中，UUID字段是一个字符串。要将UUID字段转换为UUID值，请运行以下$toUUID操作：

db.products.aggregate( [
   {
      $project: {
         name: 1,
         price: 1,
         UUID: {
            $toUUID: "$UUID"
         }
      }
   }
] )

Output:输出：

[
   {
      _id: ObjectId('669945ab610b080391a8e2f5'),
      name: 'laptop',
      price: 400,
      UUID: UUID('0e3b9063-8abd-4eb3-9f9f-f4c59fd30a60')
   }
]