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$dateFromParts (aggregation)

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Definition

$dateFromParts

New in version 3.6.

Constructs and returns a Date object given the date’s constituent properties.

The $dateFromParts expression has the following syntax:

{
    $dateFromParts : {
        'year': <year>, 'month': <month>, 'day': <day>,
        'hour': <hour>, 'minute': <minute>, 'second': <second>,
        'milliseconds': <ms>, 'timezone': <tzExpression>
    }
}

You can also specify your constituent date fields in ISO week date format using the following syntax:

{
    $dateFromParts : {
        'isoWeekYear': <year>, 'isoWeek': <week>, 'isoDayOfWeek': <day>,
        'hour': <hour>, 'minute': <minute>, 'second': <second>,
        'milliseconds': <ms>, 'timezone': <tzExpression>
    }
}

The $dateFromParts takes a document with the following fields:

Field Required/Optional Description Possible Values
year Required if not using isoWeekYear Calendar year. 0-9999
isoWeekYear Required if not using year ISO Week Date Year. 0-9999
month Optional. Can only be used with year. Month. Defaults to 1. 1-12
isoWeek Optional. Can only be used with isoWeekYear. Week of year. Defaults to 1. 1-53
day Optional. Can only be used with year. Day of month. Defaults to 1. 1-31
isoDayOfWeek Optional. Can only be used with isoWeekYear. Day of week (Monday 1 - Sunday 7). Defaults to 1. 1-7
hour Optional Hour. Defaults to 0. 0-23
minute Optional Minute. Defaults to 0. 0-59
second Optional Second. Defaults to 0. 0-59
millisecond Optional Millisecond. Defaults to 0. 0-999
timezone Optional

<timezone> can be any expression that evaluates to a string whose value is either:

  • an Olson Timezone Identifier, such as "Europe/London" or "America/New_York", or
  • a UTC offset in the form:
    • +/-[hh]:[mm], e.g. "+04:45", or
    • +/-[hh][mm], e.g. "-0530", or
    • +/-[hh], e.g. "+03".

For more information on expressions, see Expressions.

Timezone expression

Important

You cannot combine the use of calendar dates and ISO week date fields when constructing your $dateFromParts input document.

Behavior

When using an Olson Timezone Identifier in the <timezone> field, MongoDB applies the DST offset if applicable for the specified timezone.

For example, consider a sales collection with the following document:

{
   "_id" : 1,
   "item" : "abc",
   "price" : 20,
   "quantity" : 5,
   "date" : ISODate("2017-05-20T10:24:51.303Z")
}

The following aggregation illustrates how MongoDB handles the DST offset for the Olson Timezone Identifier. The example uses the $hour and $minute operators to return the corresponding portions of the date field:

db.sales.aggregate([
{
   $project: {
      "nycHour": {
         $hour: { date: "$date", timezone: "-05:00" }
       },
       "nycMinute": {
          $minute: { date: "$date", timezone: "-05:00" }
       },
       "gmtHour": {
          $hour: { date: "$date", timezone: "GMT" }
       },
       "gmtMinute": {
          $minute: { date: "$date", timezone: "GMT" } },
       "nycOlsonHour": {
          $hour: { date: "$date", timezone: "America/New_York" }
       },
       "nycOlsonMinute": {
          $minute: { date: "$date", timezone: "America/New_York" }
       }
   }
}])

The operation returns the following result:

{
   "_id": 1,
   "nycHour" : 5,
   "nycMinute" : 24,
   "gmtHour" : 10,
   "gmtMinute" : 24,
   "nycOlsonHour" : 6,
   "nycOlsonMinute" : 24
}

Example

The following aggregation uses $dateFromParts to construct three date objects from the provided input fields:

db.sales.aggregate([
{
   $project: {
      date: {
         $dateFromParts: {
            'year' : 2017, 'month' : 2, 'day': 8, 'hour' : 12
         }
      },
      date_iso: {
         $dateFromParts: {
            'isoWeekYear' : 2017, 'isoWeek' : 6, 'isoDayOfWeek' : 3, 'hour' : 12
         }
      },
      date_timezone: {
         $dateFromParts: {
            'year' : 2016, 'month' : 12, 'day' : 31, 'hour' : 23,
            'minute' : 46, 'second' : 12, 'timezone' : 'America/New_York'
         }
      }
   }
}])

The operation returns the following result:

{
  "_id" : 1,
  "date" : ISODate("2017-02-08T12:00:00Z"),
  "date_iso" : ISODate("2017-02-08T12:00:00Z"),
  "date_timezone" : ISODate("2017-01-01T04:46:12Z")
}