$isoWeekYear (aggregation)

Definition定义

$isoWeekYear

Returns the year number in ISO 8601 format. 以ISO 8601格式返回年份号。The year starts with the Monday of week 1 and ends with the Sunday of the last week.一年从第一周的星期一开始，到最后一周的星期日结束。

The $isoWeekYear expression has the following operator expression syntax:$isoWeekYear表达式具有以下运算符表达式语法：

{ $isoWeekYear: <dateExpression> }

The argument can be:参数可以是：

• An expression that resolves to a Date, a Timestamp, or an ObjectID.解析为Date、Timestamp或ObjectID的表达式。

• A document with this format:具有以下格式的文档：

  { date: <dateExpression>, timezone: <tzExpression> }

  Field字段	Description描述
  date	The date to which the operator is applied. 运算符的应用日期。<dateExpression> must be a valid expression that resolves to a Date, a Timestamp, or an ObjectID.必须是解析为Date、Timestamp或ObjectID的有效表达式。
  timezone	Optional. 可选。The timezone of the operation result. 操作结果的时区。<tzExpression> must be a valid expression that resolves to a string formatted as either an Olson Timezone Identifier or a UTC Offset. 必须是有效的表达式，该表达式可以解析为格式为Olson时区标识符或 UTC偏移量的字符串。If no timezone is provided, the result is displayed in UTC.如果未提供timezone，则结果以UTC显示。 Format格式 Examples示例 Olson Timezone Identifier "America/New_York" "Europe/London" "GMT" UTC Offset +/-[hh]:[mm], e.g. "+04:45" +/-[hh][mm], e.g. "-0530" +/-[hh], e.g. "+03"

Behavior行为

{ $isoWeekYear: new Date("2015-05-26") }

{ $isoWeekYear: { date: new Date("Jan 7, 2003") } }

{ $isoWeekYear: ISODate("2017-01-02T00:00:00Z") }

{ $isoWeekYear: {
    date: ISODate("2017-01-02T00:00:00Z"),
    timezone: "-0500"
} }

{ $isoWeekYear: {
    date: new Date("April 08, 2024"),
    timezone: "America/Chicago"
} }

{ $isoWeekYear: "March 28, 1976" }

{ $isoWeekYear: Date("2016-01-01") }

{ $isoWeekYear: "2009-04-09" }

Example示例

A collection called anniversaries contains the following documents:名为anniversaries的集合包含以下文档：

{ "_id" : 1, "date" : ISODate("2016-01-01T00:00:00Z") }
{ "_id" : 2, "date" : ISODate("2016-01-04T00:00:00Z") }
{ "_id" : 3, "date" : ISODate("2015-01-01T00:00:00Z") }
{ "_id" : 4, "date" : ISODate("2014-04-21T00:00:00Z") }

The following operation returns the year number in ISO 8601 format for each date field.以下操作为每个date字段返回ISO 8601格式的年份号。

db.anniversaries.aggregate( [
  {
    $project: {
      yearNumber: { $isoWeekYear: "$date" }
    }
  }
] )

The operation returns the following results:该操作返回以下结果：

{ "_id" : 1, "yearNumber" : 2015 }
{ "_id" : 2, "yearNumber" : 2016 }
{ "_id" : 3, "yearNumber" : 2015 }
{ "_id" : 4, "yearNumber" : 2014 }