$isoWeek (aggregation)

Definition定义

$isoWeek

Returns the week number in ISO 8601 format, ranging from 1 to 53. 以ISO 8601格式返回周数，范围从1到53。Week numbers start at 1 with the week (Monday through Sunday) that contains the year's first Thursday.周数从1开始，周（周一到周日）包含一年的第一个星期四。

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

{ $isoWeek: <dateExpression> }

The argument can be:参数可以是：

• An expression that resolves to a Date, a Timestamp, or an ObjectID.。

• 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奥尔森时区标识符或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

{ $isoWeek: { date: new Date("Jan 4, 2016") } }

{ $isoWeek: new Date("2016-01-01") }

{ $isoWeek: {
    date: new Date("August 14, 2011"),
    timezone: "America/Chicago"
} }

{ $isoWeek: ISODate("1998-11-02T00:00:00Z") }

{ $isoWeek: {
    date: ISODate("1998-11-02T00:00:00Z"),
    timezone: "-0500"
} }

{ $isoWeek: "March 28, 1976" }

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

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

Example示例

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

{ "_id" : 1, "date" : ISODate("2006-10-24T00:00:00Z"), "city" : "Boston" }
{ "_id" : 2, "date" : ISODate("2011-08-18T00:00:00Z"), "city" : "Detroit" }

The following operation returns the week number for each date field.以下操作返回每个date字段的周数。

db.deliveries.aggregate( [
  {
    $project: {
      _id: 0,
      city: "$city",
      weekNumber: { $isoWeek: "$date" }
    }
  }
] )

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

{ "city" : "Boston", "weekNumber" : 43 }
{ "city" : "Detroit", "weekNumber" : 33 }