$isoWeekYear (aggregation)

Definition

  • $isoWeekYear

New in version 3.4.

Returns the year number in ISO 8601 format. The year startswith the Monday of week 1 and ends with the Sunday of thelast week.

The $isoWeekYear expression has the followingoperator expression syntax:

  1. { $isoWeekYear: <dateExpression> }

Changed in version 3.6.

The argument must be a valid expression that resolves to one of the following:

New in version 3.6.

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

FieldDescriptiondateThe date to which the operator is applied.<dateExpression> must be a valid expression that resolves to aDate, aTimestamp,or an ObjectID.timezoneOptional. The timezone of the operation result.<tzExpression> must be a valid expression that resolves to a string formatted as eitheran Olson Timezone Identifier or aUTC Offset.If no timezone is provided, the result is displayed in UTC.

FormatExamplesOlson Timezone Identifier

  1. "America/New_York"
  2. "Europe/London"
  3. "GMT"

UTC Offset

  1. +/-[hh]:[mm], e.g. "+04:45"
  2. +/-[hh][mm], e.g. "-0530"
  3. +/-[hh], e.g. "+03"

Behavior

ExampleResult
  1. { $isoWeekYear: new Date("2015-05-26") }
2015
  1. { $isoWeekYear: { date: new Date("Jan 7, 2003") } }
2003
  1. { $isoWeekYear: ISODate("2017-01-02T00:00:00Z") }
2017
  1. { $isoWeekYear: {    date: ISODate("2017-01-02T00:00:00Z"),    timezone: "-0500"} }
2016
  1. { $isoWeekYear: {    date: new Date("April 08, 2024"),    timezone: "America/Chicago"} }
2024
  1. { $isoWeekYear: "March 28, 1976" }
error
  1. { $isoWeekYear: Date("2016-01-01") }
error
  1. { $isoWeekYear: "2009-04-09" }
error

Note

$isoWeekYear cannot take a string as an argument.

Example

A collection called anniversaries contains the following documents:

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

The following operation returns the year number in ISO 8601format for each date field.

  1. db.anniversaries.aggregate( [
  2.   {
  3.     $project: {
  4.       yearNumber: { $isoWeekYear: "$date" }
  5.     }
  6.   }
  7. ] )

The operation returns the following results:

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

See also