$currentDate (Stream Processing)

Definition

The $currentDate expression returns the system time of your stream processing workspace each time Atlas Stream Processing evaluates it. This ensures that time fields you add from within a streaming data pipeline remain up-to-date for each processed message.

$currentDate

A $currentDate expression takes the form of an empty object {}.

Syntax

The $currentDate expression is an empty object {} and has no internal syntax.

Behavior

Pass $currentDate: {} as the value of any expression which accepts an ISODate value.

Examples

The following example demonstrates a basic use of the $currentDate expression to ensure accurate timestamps for each output document from a given stream processor.

{  "$addFields": {    "time1": {      "$currentDate": {}    }  }}

{  "a": 1,  "time1": ISODate("2025-01-24T11:57:22.033Z")}

You can use the $currentDate expression multiple times in your stream processing pipeline to generate multiple timestamps for various stages within a stream processor.

{  "$addFields": {    "time1": {      "$currentDate": {}    }  },  "$group": {    "_id": "$time1",    "count": {      "$count": {}    }  },  "$addFields": {    "time1": "$_id",    "time2": {      "$currentDate": {}    }  }}

{  "time1": ISODate("2025-01-24T11:57:22.033Z"),  "time2": ISODate("2025-01-24T11:57:26.036Z"),  "count": 1}