Node Mongodb Native Versions Save

6.6.2 (2024-05-15)

The MongoDB Node.js team is pleased to announce version 6.6.2 of the mongodb package!

Release Notes

Server Selection performance regression due to incorrect RTT measurement

Starting in version 6.6.0, when using the stream server monitoring mode, heartbeats were incorrectly timed as having a duration of 0, leading to server selection viewing each server as equally desirable for selection.

Bug Fixes

• NODE-6171: RTT set to zero when serverMonitoringMode=stream (#4110) (7a7ec5b)

Documentation

• Reference
• API
• Changelog

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

6.6.1 (2024-05-06)

The MongoDB Node.js team is pleased to announce version 6.6.1 of the mongodb package!

Release Notes

ref()-ed timer keeps event loop running until client.connect() resolves

When the MongoClient is first starting up (client.connect()) monitoring connections begin the process of discovering servers to make them selectable. The ref()-ed serverSelectionTimeoutMS timer keeps Node.js' event loop running as the monitoring connections are created. In the last release we inadvertently unref()-ed this initial timer which would allow Node.js to close before the monitors could create connections.

Bug Fixes

• NODE-6151: MongoClient connect does not keep Node.js running (#4101) (7e0d9e6)

Documentation

• Reference
• API
• Changelog

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

6.6.0 (2024-05-02)

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

Example:

// collection has no schema
collection.update(
    $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

[!Important]
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

[!Important]
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.

Summary

Features

• 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)
• NODE-6149: upgrade bson to ^6.7.0 (#4099) (7f191cf)

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)

Documentation

• Reference
• API
• Changelog

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

6.5.0 (2024-03-11)

The MongoDB Node.js team is pleased to announce version 6.5.0 of the mongodb package!

Release Notes

Bulk Write Operations Generate Ids using pkFactory

When performing inserts, the driver automatically generates _ids for each document if there is no _id present. By default, the driver generates ObjectIds. An option, pkFactory, can be used to configure the driver to generate _ids that are not object ids.

For a long time, only Collection.insert and Collection.insertMany actually used the pkFactory, if configured. Notably, Collection.bulkWrite(), Collection.initializeOrderedBulkOp() and Collection.initializeOrderedBulkOp() always generated ObjectIds, regardless of what was configured on collection.

The driver always generates _ids for inserted documents using the pkFactory.

[!CAUTION] If you are using a pkFactory and performing bulk writes, you may have inserted data into your database that does not have _ids generated by the pkFactory.

Fixed applying read preference to commands depending on topology

When connecting to a secondary in a replica set with a direct connection, if a read operation is performed, the driver attaches a read preference of primaryPreferred to the command.

Fixed memory leak in Connection layer

The Connection class has recently been refactored to operate on our socket operations using promises. An oversight how we made async network operations interruptible made new promises for every operation. We've simplified the approach and corrected the leak.

Query SRV and TXT records in parallel

When connecting using a convenient SRV connection string (mongodb+srv://) hostnames are obtained from an SRV dns lookup and some configuration options are obtained from a TXT dns query. Those DNS operations are now performed in parallel to reduce first-time connection latency.

Container and Kubernetes Awareness

The Node.js driver now keeps track of container metadata in the client.env.container field of the handshake document.

If space allows, the following metadata will be included in client.env.container:

env?: { 
  container?: {
    orchestrator?: 'kubernetes' // if process.env.KUBERNETES_SERVICE_HOST is set
    runtime?: 'docker' // if the '/.dockerenv' file exists
  } 
}

Note: If neither Kubernetes nor Docker is present, client.env will not have the container property.

Add property errorResponse to MongoServerError

The MongoServer error maps keys from the error document returned by the server on to itself. There are some use cases where the original error document is desirable to obtain in isolation. So now, the mongoServerError.errorResponse property stores a reference to the error document returned by the server.

Deprecated unused CloseOptions interface

The CloseOptions interface was unintentionally made public and was only intended for use in the driver's internals. Due to recent refactoring (NODE-5915), this interface is no longer used in the driver. Since it was marked public, out of an abundance of caution we will not be removing it outside of a major version, but we have deprecated it and will be removing it in the next major version.

Features

• NODE-5968: container and Kubernetes awareness in client metadata (#4005) (28b7040)
• NODE-5988: Provide access to raw results doc on MongoServerError (#4016) (c023242)
• NODE-6008: deprecate CloseOptions interface (#4030) (f6cd8d9)

Bug Fixes

• NODE-5636: generate _ids using pkFactory in bulk write operations (#4025) (fbb5059)
• NODE-5981: read preference not applied to commands properly (#4010) (937c9c8)
• NODE-5985: throw Nodejs' certificate expired error when TLS fails to connect instead of CERT_HAS_EXPIRED (#4014) (057c223)
• NODE-5993: memory leak in the Connection class (#4022) (69de253)

Performance Improvements

• NODE-5986: parallelize SRV/TXT resolution (#4012) (eab8f23)

Documentation

• Reference
• API
• Changelog

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

6.4.0 (2024-02-29)

The MongoDB Node.js team is pleased to announce version 6.4.0 of the mongodb package!

Release Notes

Server selection will use a different Mongos on retry

When retrying reads or writes on a sharded cluster, the driver will attempt to select a different mongos for the retry if multiple are present. This should heuristically avoid encountering the original error that caused the need to retry the operation.

Caching AWS credentials provider per client

Instead of creating a new AWS provider for each authentication, we cache the AWS credentials provider per client to prevent overwhelming the auth endpoint and ensure that cached credentials are not shared with other clients.

BSON upgraded to ^6.4.0

BSON has had a number of performance increases in the last two releases (6.3.0 and 6.4.0). Small basic latin (ASCII) only strings, small memory allocations (ObjectId and Decimal128) and numeric parsing operations (int32, doubles, and longs) have all had optimizations applied to them.

For details check out the release notes here: BSON 6.3.0 and BSON 6.4.0 :racehorse:

ExceededTimeLimit was made a retryable reads error

Read operations will be retried after receiving an error with the ExceededTimeLimit label.

Fixed unresolved request issue in KMS requester

Internal to the field-level encryption machinery is a helper that opens a TLS socket to the KMS provider endpoint and submits a KMS request. The code neglected to add a 'close' event listener to the socket, which had the potential to improperly leave the promise pending indefinitely if no error was encountered.

The base64 padding is now preserved in the saslContinue command

The authentication was rejected by the saslContinue command from mongosh due to missing "=" padding from the client. We fixed the way we parse payload to preserve trailing "="s.

countDocuments now types the filter using the collection Schema

Previously, countDocuments had a weakly typed Document type for the filter allowing any JS object as input. The filter is now typed as Filter<Schema> to enable autocompletion, and, hopefully, catch minor bugs.

Thank you to @pashok88895 for contributing to this improvement.

The type error with $addToSet in bulkWrite was fixed

Previously the following code sample would show a type error:

interface IndexSingatureTestDocument extends Document {
    readonly myId: number;
    readonly mySet: number[];
  }
const indexSingatureCollection = undefined as unknown as Collection<IndexSingatureTestDocument>;
indexSingatureCollection.bulkWrite([
  {
    updateOne: {
      filter: { myId: 0 },
      update: {
        $addToSet: { mySet: 0 } // The type error! Type 'number' is not assignable to type 'never'.
      }
    }
  }
]);

It happened because the driver's Document type falls back to any, and internally we could not distinguish whether or not this assignment was intentional and should be allowed.

After this change, users can extend their types from Document/any, or use properties of any type and we skip the $addToSet validation in those cases.

Fixed heartbeat duration including socket creation

The ServerHeartbeatSucceeded and ServerHeartbeatFailed event have a duration property that represents the time it took to perform the hello handshake with MongoDB. The Monitor responsible for issuing heartbeats mistakenly included the time it took to create the socket in this field, which inflates the value with the time it takes to perform a DNS lookup, TCP, and TLS handshakes.

Errors on cursor transform streams are now properly propagated.

These were previously swallowed and now will be emitted on the error event:

const transform = new Transform({
  transform(data, encoding, callback) {
    callback(null, data);
  },
});
const stream = db.collection('tests').find().sort({ studentId: -1 }).stream({ transform });
stream.on('error', err => {
  // The error will properly be emitted here.
});

The AWS token is now optional

Users may provide an AWS_SESSION_TOKEN as a client option or AWS configuration in addition to a username and password. But if the token is not provided, the driver won't throw an exception and let AWS SDK handle the request.

Features

• NODE-3449: Add serverConnectionId to Command Monitoring Spec (735f7aa)
• NODE-3470: retry selects another mongos (#3963) (84959ee)
• NODE-3689: require hello command for connection handshake to use OP_MSG disallowing OP_QUERY (#3938) (ce7df0f)
• NODE-5717: make ExceededTimeLimit retryable reads error (#3947) (106ab09)
• NODE-5939: Implement 6.x: cache the AWS credentials provider in the MONGODB-AWS auth logic (#3991) (e0a37e5)
• NODE-5978: upgrade BSON to ^6.4.0 (#4007) (90f2f70)
  • NODE-5885: upgrade BSON to ^6.3.0 (#3983) (9401d09)

Bug Fixes

• NODE-5127: implement reject kmsRequest on server close (#3964) (568e05f)
• NODE-5609: node driver omits base64 padding in sasl-continue command (#3975) (b7d28d3)
• NODE-5765: change type for countDocuments (#3932) (22cae0f)
• NODE-5791: type error with $addToSet in bulkWrite (#3953) (b93d405)
• NODE-5840: heartbeat duration includes socket creation (#3973) (a42039b)
• NODE-5901: propagate errors to transformed stream in cursor (#3985) (ecfc615)
• NODE-5944: make AWS session token optional (#4002) (f26de76)

Performance Improvements

• NODE-5771: improve new connection (#3948) (a4776cf)
• NODE-5928: consolidate signal use and abort promise wrap (#3992) (38742c2)

Documentation

• Reference
• API
• Changelog

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

5.9.2 (2023-11-16)

The MongoDB Node.js team is pleased to announce version 5.9.2 of the mongodb package!

Release Notes

Fix connection leak when serverApi is enabled

When enabling serverApi the driver's RTT mesurment logic (used to determine the closest node) still sent the legacy hello command "isMaster" causing the server to return an error. Unfortunately, the error handling logic did not correctly destroy the socket which would cause a leak.

Both sending the correct hello command and the error handling connection clean up logic are fixed in this change.

Bug Fixes

• NODE-5750: RTTPinger always sends legacy hello (#3922) (8e56872)

Documentation

• Reference
• API
• Changelog

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

4.17.2 (2023-11-16)

The MongoDB Node.js team is pleased to announce version 4.17.2 of the mongodb package!

Release Notes

Fix connection leak when serverApi is enabled

When enabling serverApi the driver's RTT mesurment logic (used to determine the closest node) still sent the legacy hello command "isMaster" causing the server to return an error. Unfortunately, the error handling logic did not correctly destroy the socket which would cause a leak.

Both sending the correct hello command and the error handling connection clean up logic are fixed in this change.

Bug Fixes

• NODE-5751: RTTPinger always sends legacy hello (#3923) (bc3d020)

Documentation

• Reference
• API
• Changelog

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

6.3.0 (2023-11-15)

The MongoDB Node.js team is pleased to announce version 6.3.0 of the mongodb package!

Release Notes

New client option serverMonitoringMode

For users that want to control the behaviour of the monitoring connection between each node in the topology, a new option, serverMonitoringMode, has been added. This defaults to auto but can be forced into a specific mode by providing a value of poll or stream. When the setting is auto the monitoring mode will be determined by the environment the driver is running in, specifically, FaaS environments prefer "polling" mode and all others prefer "streaming".

A polling monitor periodically issues a hello command to the node at an interval of heartbeatFrequencyMS. A streaming monitor sends an initial hello and then will automatically get a response from the Node when a change in server configuration occurs or at a maximum time of heartbeatFrequencyMS. The value of that option defaults to 10000 milliseconds.

This new option can be provided in the connection string or as an option to the MongoClient.

// In the connection string.
new MongoClient('mongodb://127.0.0.1:27017/?serverMonitoringMode=stream');

// In the options
new MongoClient('mongodb://127.0.0.1:27017/', { serverMonitoringMode: 'stream' });

Fix connection leak when serverApi is enabled

When enabling serverApi the driver's RTT measurement logic (used to determine the closest node) still sent the legacy hello command "isMaster" causing the server to return an error. Unfortunately, the error handling logic did not correctly destroy the socket which would cause a leak.

Both sending the correct hello command and the error handling connection clean-up logic are fixed in this change.

GridFS fields deprecated

The GridFS contentType and aliases options are deprecated. According to the GridFS spec, applications wishing to store contentType and aliases should add a corresponding field to the metadata document instead.

Remove deprecation warning about punycode

The mongodb-connection-string-url package which parses connection strings relied on Node's punycode module, the package now imports the community package removing the deprecation warning on Node.js 20+.

Features

• NODE-3881: require hello command + OP_MSG when 'loadBalanced=True' (#3907) (fd58eec)
• NODE-5197: add server monitoring mode (#3899) (ae4c94a)
• NODE-5590: deprecate GridFS fields (#3905) (d2225da)

Bug Fixes

• NODE-4863: do not use RetryableWriteError for non-server errors (#3914) (08c9fb4)
• NODE-5709: bump mongodb-connection-string-url to 3.0.0 (#3909) (1c3dc02)
• NODE-5749: RTTPinger always sends legacy hello (#3921) (ebbfb8a)

Documentation

• Reference
• API
• Changelog

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

6.2.0 (2023-10-19)

The MongoDB Node.js team is pleased to announce version 6.2.0 of the mongodb package!

Release Notes

Updated to BSON 6.2.0

BSON now prints in full color! :rainbow: :rocket:

See our release notes for BSON 6.2.0 here for more examples!

insertedIds in bulk write now contain only successful insertions

Prior to this fix, the bulk write error's result.insertedIds property contained the _id of each attempted insert in a bulk operation.

Now, when a bulkwrite() or an insertMany() operation rejects one or more inserts, throwing an error, the error's result.insertedIds property will only contain the _id fields of successfully inserted documents.

Fixed edge case leak in findOne()

When running a findOne against a time series collection, the driver left the implicit session for the cursor un-ended due to the way the server returns the resulting cursor information. Now the cursor will always be cleaned up regardless of the outcome of the find operation.

Removed client-side collection and database name validation

Database and collection name checking will now be in sync with the MongoDB server's naming restrictions. Specifically, users can now create collections that start or end with the '.' character.

Features

• NODE-5613: add awaited field to SDAM heartbeat events (#3895) (b50aadc)
• update bson to 6.2.0 (#3898) (32b7176)

Bug Fixes

• NODE-5496: remove client-side collection and database name check validation (#3873) (98550c6)
• NODE-5628: bulkWriteResult.insertedIds does not filter out _ids that are not actually inserted (#3867) (09f2a67)
• NODE-5706: make findOne() close implicit session to avoid memory leak (#3897) (995d138)

Documentation

• Reference
• API
• Changelog

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

5.9.1 (2023-10-18)

The MongoDB Node.js team is pleased to announce version 5.9.1 of the mongodb package!

Release Notes

insertedIds in bulk write now contain only successful insertions

Prior to this fix, the bulk write error's result.insertedIds property contained the _id of each attempted insert in a bulk operation.

Now, when a bulkwrite() or an insertMany() operation rejects one or more inserts, throwing an error, the error's result.insertedIds property will only contain the _id fields of successfully inserted documents.

Fixed edge case leak in findOne()

When running a findOne against a time series collection, the driver left the implicit session for the cursor un-ended due to the way the server returns the resulting cursor information. Now the cursor will always be cleaned up regardless of the outcome of the find operation.

Bug Fixes

• NODE-5627: BulkWriteResult.insertedIds includes ids that were not inserted (#3870) (d766ae2)
• NODE-5691: make findOne() close implicit session to avoid memory leak (#3889) (0d6c9cd)

Documentation

• Reference
• API
• Changelog

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