In MongoDB, the $year aggregation pipeline operator returns the year portion of a given date.
When using the $year operator, you can optionally specify a timezone to use for the result.
The $year operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $isoWeekYear aggregation pipeline operator returns the ISO week-numbering year for a given date value. This is the year number in ISO 8601 format.
When using the $isoWeekYear operator, you can optionally specify a timezone to use for the result.
The $isoWeekYear operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $isoWeek aggregation pipeline operator returns the week number in ISO 8601 format, ranging from 1 to 53.
When using the $isoWeek operator, you can optionally specify a timezone to use for the result.
The $isoWeek operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $isoDayOfWeek aggregation pipeline operator returns the weekday number in ISO 8601 format, ranging from 1 (for Monday) to 7 (for Sunday).
You can optionally specify a timezone to use for the result.
The $isoDayOfWeek operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $dayOfWeek aggregation pipeline operator returns the day of the week for a date as a number between 1 (Sunday) and 7 (Saturday).
You can optionally specify a timezone to use for the result.
The $dayOfWeek operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $dayOfMonth aggregation pipeline operator returns the day of the month for a date as a number between 1 and 31.
You can optionally specify a timezone to use for the result.
The $dayOfMonth operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $dayOfYear aggregation pipeline operator returns the day of the year for a date as a number between 1 and 366.
You can optionally specify a timezone to use for the result.
The $dayOfYear operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $currentDate operator 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.
$currentDate is an update operator, and can only be used when updating documents, not when inserting them (although it can be used in upsert operations).
In MongoDB, the $toDate aggregation operator converts a value to a date
$toDate takes any valid expression. If the expression can’t be converted to a date, it returns an error. If the expression is null or missing, it returns null.
I thought it would be interesting to run a few quick queries to see how various formatting strings affect the formatting of date/time values.