$currentDate

Definition

$currentDate

The $currentDate operator sets the value of a field to the current date, either as a Date or a timestamp. The default type is Date.

Compatibility

You can use $currentDate for deployments hosted in the following environments:

• MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

• MongoDB Enterprise: The subscription-based, self-managed version of MongoDB

• MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

Syntax

The $currentDate operator has the form:

{ $currentDate: { <field1>: <typeSpecification1>, ... } }

<typeSpecification> can be either:

• a boolean true to set the field value to the current date as a Date, or

• a document { $type: "timestamp" } or { $type: "date" } which explicitly specifies the type. The operator is case-sensitive and accepts only the lowercase "timestamp" or the lowercase "date".

To specify a <field> in an embedded document or in an array, use dot notation.

Behavior

In MongoDB 4.4 and earlier, update operators process document fields in lexicographic order. See Update Operators Behavior for details.

$currentDate sets the specified field to the date when $currentDate was run.

If the field does not exist, $currentDate adds the field to a document.

Example

Create a sample collection customers with the following document:

db.customers.insertOne(
   { _id: 1, status: "a", lastModified: ISODate("2013-10-02T01:11:18.965Z") }
)

The following operation updates the lastModified field to the current date, the "cancellation.date" field to the current timestamp as well as updating the status field to "D" and the "cancellation.reason" to "user request".

db.customers.updateOne(
   { _id: 1 },
   {
     $currentDate: {
        lastModified: true,
        "cancellation.date": { $type: "timestamp" }
     },
     $set: {
        "cancellation.reason": "user request",
        status: "D"
     }
   }
)

$currentDate sets the specified field to the date when $currentDate was run.

To verify the update:

db.customers.find().pretty()

The updated document resembles:

{
   "_id" : 1,
   "status" : "D",
   "lastModified" : ISODate("2020-01-22T21:21:41.052Z"),
   "cancellation" : {
      "date" : Timestamp(1579728101, 1),
      "reason" : "user request"
   }
}

The lastModified field is set to the date when $currentDate was run in the update example shown earlier.

db.customers.updateOne(
  { _id: 1 },
  [
   { $set: { lastModified: "$$NOW", cancellation: {date: "$$CLUSTER_TIME", reason: "user request"}, status: "D" } }
  ]
)

db.customers.find().pretty()

{
   "_id" : 1,
   "status" : "D",
   "lastModified" : ISODate("2020-01-22T21:02:18.994Z"),
   "cancellation" : {
      "date" : Timestamp(1579726934, 2),
      "reason" : "user request"
   }
}