MongoDB NodeJS Driver 6.6.0 Release

The MongoDB Node.js team is pleased to announce version 6.6.0 of the mongodb package!

:seedling: A new release!

6.6.0 (2024-05-01)

The MongoDB Node.js team is pleased to announce version 6.6.0 of the mongodb package!

Release Notes

Aggregation pipelines can now add stages manually

When creating an aggregation pipeline cursor, a new generic method addStage() has been added in the fluid API for users to add aggregation pipeline stages in a general manner.

const documents = await users.aggregate().addStage({ $project: { name: true } }).toArray();

Thank you @prenaissance for contributing this feature!

cause and package name included for MongoMissingDependencyErrors

MongoMissingDependencyErrors now include a cause and a dependencyName field, which can be used to programmatically determine which package is missing and why the driver failed to load it.

For example:

MongoMissingDependencyError: The iHateJavascript module does not exist
    at findOne (mongodb/main.js:7:11)
    at Object.<anonymous> (mongodb/main.js:14:1)
    ... 3 lines matching cause stack trace ...
    at Module._load (node:internal/modules/cjs/loader:1021:12) {
  dependencyName: 'iHateJavascript',
  [Symbol(errorLabels)]: Set(0) {},
  [cause]: Error: Cannot find module 'iHateJavascript'
  Require stack:
  - mongodb/main.js
      at require (node:internal/modules/helpers:179:18)
      at findOne (mongodb/main.js:5:5)
      at Object.<anonymous> (mongodb/main.js:14:1) {
    code: 'MODULE_NOT_FOUND',
    requireStack: [ 'mongodb/main.js' ]

ServerDescription Round Trip Time (RTT) measurement changes

(1) ServerDescription.roundTripTime is now a moving average

Previously, ServerDescription.roundTripTime was calculated as a weighted average of the most recently observed heartbeat duration and the previous duration. This update changes this behaviour to average ServerDescription.roundTripTime over the last 10 observed heartbeats. This should reduce the likelihood that the selected server changes as a result of momentary spikes in server latency.

(2) Added minRoundTripTime to ServerDescription

A new minRoundTripTime property is now available on the ServerDescription class which gives the minimum RTT over the last 10 heartbeats. Note that this value will be reported as 0 when fewer than 2 samples have been observed.

type supported in SearchIndexDescription

It is now possible to specify the type of a search index when creating a search index:

const indexName = await collection.createSearchIndex({
  name: 'my-vector-search-index',
  // new! specifies that a `vectorSearch` index is created
  type: 'vectorSearch',
  definition: {
    mappings: { dynamic: false }

Collection.findOneAndModify’s UpdateFilter.$currentDate no longer throws on collections with limited schema


// collection has no schema
    $currentData: {
       lastModified: true
    } // no longer throws a TS error

TopologyDescription now properly stringifies itself to JSON

The TopologyDescription class is exposed by the driver in server selection errors and topology monitoring events to provide insight into the driver’s current representation of the server’s topology and to aid in debugging. However, the TopologyDescription uses Maps internally, which get serialized to {} when JSON stringified. We recommend using Node’s util.inspect() helper to print topology descriptions because inspect properly handles all JS types and all types we use in the driver. However, if JSON must be used, the TopologyDescription now provides a custom toJSON() hook:

client.on('topologyDescriptionChanged', ({ newDescription }) => {
   // recommended!
	console.log('topology description changed', inspect(newDescription, { depth: Infinity, colors: true }))

    // now properly prints the entire topology description
	console.log('topology description changed', JSON.stringify(newDescription))

Omit readConcern and writeConcern in Collection.listSearchIndexes options argument

readConcern and writeConcern are no longer viable keys in the options argument passed into Collection.listSearchIndexes

This type change is a correctness fix.

Collection.listSearchIndexes is an Atlas specific method, and Atlas’ search indexes do not support readConcern and writeConcern options. The types for this function now reflect this functionality.

Don’t throw error when non-read operation in a transaction has a ReadPreferenceMode other than 'primary'

The following error will now only be thrown when a user provides a ReadPreferenceMode other than primary and then tries to perform a command that involves a read:

new MongoTransactionError('Read preference in a transaction must be primary');

Prior to this change, the Node Driver would incorrectly throw this error even when the operation does not perform a read.
Note: a RunCommandOperation is treated as a read operation for this error.

TopologyDescription.error type is MongoError

The TopologyDescription.error property type is now MongoError rather than MongoServerError.

This type change is a correctness fix.

Before this change, the following errors that were not instances of MongoServerError were already passed into TopologyDescription.error at runtime:

  • MongoNetworkError (excluding MongoNetworkRuntimeError)
  • MongoError with a MongoErrorLabel.HandshakeError label

indexExists() no longer supports the full option

The Collection.indexExists() helper supported an option, full, that modified the internals of the method. When full was set to true, the driver would always return false, regardless of whether or not the index exists.

The full option is intended to modify the return type of index enumeration APIs (Collection.indexes() and Collection.indexInformation(), but since the return type of Collection.indexExists() this option does not make sense for the Collection.indexExists() helper.

We have removed support for this option.

indexExists(), indexes() and indexInformation() support cursor options in Typescript

These APIs have supported cursor options at runtime since the 4.x version of the driver, but our Typescript has incorrectly omitted cursor options from these APIs.

Index information helpers have accurate Typescript return types

Collection.indexInformation(), Collection.indexes() and Db.indexInformation() are helpers that return index information for a given collection or database. These helpers take an option, full, that configures whether the return value contains full index descriptions or a compact summary:

collection.indexes({ full: true });   // returns an array of index descriptions
collection.indexes({ full: false });  // returns an object, mapping index names to index keys

However, the Typescript return type of these helpers was always Document. Thanks to @prenaissance, these helpers now have accurate type information! The helpers return a new type, IndexDescriptionCompact | IndexDescriptionInfo[], which accurately reflects the return type of these helpers. The helpers also support type narrowing by providing a boolean literal as an option to the API:

collection.indexes();   // returns `IndexDescriptionCompact | IndexDescriptionInfo[]`
collection.indexes({ full: false });  // returns an `IndexDescriptionCompact`
collection.indexes({ full: true });  // returns an `IndexDescriptionInfo[]`

collection.indexInfo();   // returns `IndexDescriptionCompact | IndexDescriptionInfo[]`
collection.indexInfo({ full: false });  // returns an `IndexDescriptionCompact`
collection.indexInfo({ full: true });  // returns an `IndexDescriptionInfo[]`

db.indexInfo();   // returns `IndexDescriptionCompact | IndexDescriptionInfo[]`
db.indexInfo({ full: false });  // returns an `IndexDescriptionCompact`
db.indexInfo({ full: true });  // returns an `IndexDescriptionInfo[]`

AWS credentials with expirations no longer throw when using on-demand AWS KMS credentials

In addition to letting users provide KMS credentials manually, client-side encryption supports fetching AWS KMS credentials on-demand using the AWS SDK. However, AWS credential mechanisms that returned access keys with expiration timestamps caused the driver to throw an error.

The driver will no longer throw an error when receiving an expiration token from the AWS SDK.

ClusterTime interface signature optionality

The ClusterTime interface incorrectly reported the signature field as required, the server may omit it, so the typescript has been updated to reflect reality.



  • NODE-3639: add a general stage to the aggregation pipeline builder (#4079) (8fca1aa)
  • NODE-5678: add options parsing support for timeoutMS and defaultTimeoutMS (#4068) (ddd1e81)
  • NODE-5762: include cause and package name for all MongoMissingDependencyErrors (#4067) (62ea94b)
  • NODE-5825: add minRoundTripTime to ServerDescription and change roundTripTime to a moving average (#4059) (0e3d6ea)
  • NODE-5919: support new type option in create search index helpers (#4060) (3598c23)
  • NODE-6020: upgrade bson to ^6.5.0 (#4035) (8ab2055)

Bug Fixes

  • NODE-3681: Typescript error in Collection.findOneAndModify UpdateFilter.$currentDate (#4047) (a8670a7)
  • NODE-5530: make topology descriptions JSON stringifiable (#4070) (3a0e011)
  • NODE-5745: ignore Read/Write Concern in Atlas Search Index Helpers (#4042) (67d7bab)
  • NODE-5925: driver throws error when non-read operation in a transaction has a ReadPreferenceMode other than primary (#4075) (39fc198)
  • NODE-5971: attach v to createIndexes command when version is specified (#4043) (1879a04)
  • NODE-5999: Change TopologyDescription.error type to MongoError (#4028) (30432e8)
  • NODE-6019: indexExists always returns false when full is set to true (#4034) (0ebc1ac)
  • NODE-6029: update types for collection listing indexes (#4072) (232bf3c)
  • NODE-6051: only provide expected allowed keys to libmongocrypt after fetching AWS KMS credentials (#4057) (c604e74)
  • NODE-6066: ClusterTime.signature can be undefined (#4069) (ce55ca9)

Performance Improvements

  • NODE-6127: move error construction into setTimeout callback (#4094) (6abc074)


We invite you to try the mongodb library immediately, and report any issues to the NODE project.