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$isoWeek (aggregation)

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  • Definition
  • Behavior
  • Example
$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:

  • A Date, a Timestamp, or an ObjectID.
  • A document of the following form:

    New in version 3.6.

    { date: <dateExpression>, timezone: <tzExpression> }
    Field
    Description
    date
    The date to which the operator is applied. <dateExpression> must be a valid expression that resolves to a Date, a Timestamp, or an ObjectID.
    timezone

    Optional. 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"
Example
Result
{ $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.

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 }
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