$isoWeek (aggregation)

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Definition

  • $isoWeek
    • New in version 3.4.

Returns the week number in ISO 8601 format, ranging from 1 to 53 . Week numbers start at 1 with the week (Monday through Sunday) that contains the year’s first Thursday.

The $isoWeek expression has the following operator expression syntax:

{ $isoWeek: <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.

{ date: <dateExpression>, timezone: <tzExpression> }
FieldDescription
dateThe date to which the operator is applied. <dateExpression> must be a valid expression that resolves to a Date, a Timestamp, or an ObjectID.
timezoneOptional. The timezone of the operation result. <tzExpression> must be a valid expression that resolves to a string formatted as either an Olson Timezone Identifier or a UTC Offset. If no timezone is provided, the result is displayed in UTC .
| Format | Examples |
| 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

ExampleResult
{ $isoWeek: { date: new Date("Jan 4, 2016") } }1
{ $isoWeek: new Date("2016-01-01") }53
{ $isoWeek: {
date: new Date("August 14, 2011"),
timezone: "America/Chicago"
} }
32
{ $isoWeek: ISODate("1998-11-02T00:00:00Z") }45
{ $isoWeek: {
date: ISODate("1998-11-02T00:00:00Z"),
timezone: "-0500"
} }
44
{ $isoWeek: "March 28, 1976" }error
{ $isoWeek: Date("2016-01-01") }error
{ $isoWeek: "2009-04-09" }error

Note

$isoWeek cannot take a string as an argument.

Example

A collection called deliveries contains the following documents:

{ "_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.

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

The operation returns the following results:

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