This article contains a list of date operators, methods, and variables that you can use when working with dates in MongoDB.

Field Update Operators

Operator	Description
$currentDate	Sets the value of a field to the current date. It can be set as either a Date or a timestamp type. The default is Date.

Date Expression Operators (Aggregation Pipeline)

The following aggregation pipeline operators return date objects or components of a date object. These can be used to construct expressions for use in the aggregation pipeline stages.

Operator	Description
$dateFromParts	Constructs a BSON Date object from the date’s constituent parts.
$dateFromString	Converts a date/time string to a date object.
$dateToParts	Returns a document containing the constituent parts of a date.
$dateToString	Returns the date as a string.
$dayOfMonth	Returns the day of the month for a given date as a number between 1 and 31.
$dayOfWeek	Returns the day of the week for a given date as a number between 1 (Sunday) and 7 (Saturday).
$dayOfYear	Returns the day of the year for a given date as a number between 1 and 366 (leap year).
$hour	Returns the hour for a given date as a number between 0 and 23.
$isoDayOfWeek	Returns the weekday number of a given date in ISO 8601 format, ranging from 1 (for Monday) to 7 (for Sunday).
$isoWeek	Returns the week number of a given date in ISO 8601 format, ranging from 1 to 53.
$isoWeekYear	Returns the year number for a given date in ISO 8601 format.
$millisecond	Returns the milliseconds of a given date as a number between 0 and 999.
$minute	Returns the minute for a given date as a number between 0 and 59.
$month	Returns the month for a given date as a number between 1 (January) and 12 (December).
$second	Returns the seconds for a given date as a number between 0 and 60 (leap seconds).
$toDate	Converts a value to a Date.
$week	Returns the week number for a given date as a number between 0 (the partial week that precedes the first Sunday of the year) and 53 (leap year).
$year	Returns the year for a given date as a number (e.g. 2021).

Methods

The following method can be used to return either a date/time string or a Date object.

Method	Description
Date()	Returns either a date/time string or a Date object. You can provide a date. If you don’t , it will return the current date/time.

System Variables

The following system variables can be used to return a datetime or timestamp value when using an aggregation pipeline.

Method	Description
NOW	Returns the current datetime value. This variable was introduced in MongoDB version 4.2.
CLUSTER_TIME	Returns the current timestamp value. Only available on replica sets and sharded clusters. This variable was introduced in MongoDB version 4.2.