Release Notes

What's New in 3.2

The 3.2 driver release includes the following new features:

• Adds a new ObjectSerializerAllowedTypesConvention convention that allows you to specify which types are allowed to be serialized and deserialized by the object serializer. To learn more about conventions, see the Conventions guide.

• Adds a new constructor for the EnumRepresentationConvention class that allows you use the topLevelOnly parameter to specify whether the convention applies to only enum properties or to all properties that include collections of enums.

  You can instantiate the EnumRepresentationConvention class by using the new constructor as shown in the following example:

  EnumRepresentationConvention(BsonType representation, bool topLevelOnly);

• Optimizes client-side projections to retrieve only the required fields from the server, rather than retrieving all fields and then filtering them.

• Adds the following classes to support binary vector representations in MongoDB Vector Search:

  • BinaryVectorFloat32

  • BinaryVectorInt8

  • BinaryVectorPackedBit

  To learn more about MongoDB Vector Search with the .NET/C# Driver, see the Run a MongoDB Vector Search Query guide.

• Adds the DocumentFormat property to the DateOnlySerializer. This property allows you to customize the way that the driver serializes DateOnly values. This release also adds the [BsonDateOnlyOptions()] attribute to customize serialization behavior for DateOnly values at the property level. To learn more, see the Custom DateOnly Serialization section of the POCOs guide.

What's New in 3.1

The 3.1 driver release includes the following new features:

• Adds new default serializers for immutable collections in the System.Collections.Immutable namespace. The driver can now serialize ImmutableArray objects, and serialization for other immutable collections is more memory efficient.

• Adds the SearchIndexType type to support creation of MongoDB Vector Search indexes programmatically. To learn more, see the MongoDB Search and MongoDB Vector Search Indexes guide.

• Adds support for the token field type and array field expressions with MongoDB Search builders for the equals operator. To learn more about using MongoDB Search with the .NET/C# Driver, see MongoDB Search.

• Adds support for the following MongoDB Search queries:

  • Using the Equals() operator method on null and Guid values

  • Using the In() operator method on Guid values

  To learn more about these methods, see the MongoDB Search Operators and Collectors section of the MongoDB Search guide.

• Adds support for sequential pagination in MongoDB Search.

• Adds support for valid SRV hostnames with fewer than 3 parts.

• Adds support for the Exists, IsMissing, and IsNullOrMissing methods in MongoDB Query API filters.

• Adds support for Exact Nearest Neighbor (ENN) vector search. To learn more about ENN Vector Search, see Run Vector Search Queries in the MongoDB Search documentation.

• Adds a sort option for update and replace operations. This change allows you to set a sort order if multiple documents match your filter when attempting to update or replace a single document. To learn more, see the Update One and Update Many guides.

For more information about this release, see the v3.1 release notes.

What's New in 3.0

The 3.0 driver release includes the following new features:

• Adds the MongoClientSettings.TranslationOptions connection option, which specifies options for translating LINQ queries to the Query API. See Specify Connection Options for more information.

• Adds support for the Half type, which represents a half-precision floating-point number. This type is available in .NET 5 and later. To learn more about the Half type, see the Half Struct API reference page on MSDN.

• The IMongoClient interface inherits the IDisposable interface. As a result, the MongoClient class and other classes that implement the IMongoClient interface contain a Disp- Adds support for the ``sort option to be passed to update commands.ose()`` method, which disposes of the client. This method does not dispose the underlying cluster and connections to the MongoDB server. To dispose of the cluster and connections, call the ClusterRegistry.UnregisterAndDisposeCluster() method. The implementation of the IDisposable interface is experimental.

  To learn more about the IDisposable interface and use of the Dispose() method, see Dispose Pattern on MSDN.

• Adds support for the DateOnly type, which represents a date value with no time component. This type is available in .NET 6 and later. To learn more about the DateOnly type, see the DateOnly Struct. API reference page on MSDN.

• Adds support for the TimeOnly type, which represents a time value with no date component. This type is available in .NET 6 and later. To learn more about the TimeOnly type, see the TimeOnly Struct. API reference page on MSDN.

• Adds support for implicit client-side projection when using the Find() method, the Select() method, or the Project() aggregation stage with the LINQ3 provider. In previous versions of the driver, you could perform client-side projection with the LINQ3 provider only after calling the ToEnumerable() or AsEnumerable() method.

  To learn how to enable and use client-side projection for a driver method, select the corresponding tab:

  Find() Method

  Select() Method

  Project() Method

  // Enable client-side projection
  var findOptions = new FindOptions();
  findOptions.TranslationOptions = new ExpressionTranslationOptions
  {
      EnableClientSideProjections = true
  };
  var find = collection
      .Find(doc => doc.Id == 1, findOptions);
      .Project(doc => new { R = MyFunction(doc.Name) });

  // Enable client-side projection
  var aggregateOptions = new AggregateOptions();
  aggregateOptions.TranslationOptions = new ExpressionTranslationOptions
  {
      EnableClientSideProjections = true
  };
  var queryable = collection
      .AsQueryable(aggregateOptions)
      .Where(doc => doc.Id == 1)
      .Select(doc => new { R = MyFunction(doc.Name) });

  // Enable client-side projection
  var aggregateOptions = new AggregateOptions();
  aggregateOptions.TranslationOptions = new ExpressionTranslationOptions
  {
      EnableClientSideProjections = true
  };
  var aggregate = collection
      .Aggregate(aggregateOptions)
      .Project(doc => new { R = MyFunction(doc.Name) });

  Tip

  MongoClientSettings

  To enable client-side projection for all queries on a client, set the TranslationOptions property of your MongoClientSettings object, as shown in the following example:

  clientSettings.TranslationOptions = new ExpressionTranslationOptions
  {
      EnableClientSideProjections = true
  };

  To learn more about using the aggregation pipeline with the .NET/C# Driver, see Aggregation Operations.

• Adds a MongoClient API for bulk write operations. To learn more about bulk write operations, see Bulk Write Operations.

For more information about this release, see the v3.0 release notes.

What's New in 2.30

The 2.30 driver doesn't introduce new features or bug fixes. Its purpose is to ease migration to v3.x of the .NET/C# Driver by marking the public APIs that were removed in v3.0 as obsolete.

What's New in 2.29

The 2.29 driver release adds support for MongoDB Server version 8.0 and includes the following new features:

• Adds support for v2 of the Queryable Encryption range protocol.

• Adds support for range indexes for Queryable Encryption. For more information about Queryable Encryption, see Queryable Encryption in the MongoDB Server manual.

For more information about this release, see the v2.29 release notes.

What's New in 2.28

The 2.28 driver release includes the following new features:

• Adds support for additional numeric conversions involving Nullable<T>.

• Adds support for the delegated option when using KMIP for CSFLE or Queryable Encryption.

For more information about this release, see the v2.28 release notes.

What's New in 2.27

The 2.27 driver release includes the following new features:

• Adds support for the $sample aggregation operator.

• Implements the Equals() method for serializers in LINQ3.

• Ensures that read and write concerns are not applied to MongoDB Search Index Helper commands to avoid errors.

• Disallows the use of the comma character in authMechanismProperties connection string values when using the MONGODB-OIDC authentication mechanism.

• Fixes a translation bug that caused an error during serialization involving numbers of different sizes.

• Adds support for Linux distributions that use the libdl.so.2 library.

For more information about this release, see the v2.27 release notes.

What's New in 2.26

The 2.26 driver release includes the following new features:

• Added support for using the SelectMany() aggregation method within Select() and Project() aggregation stages.

• Added support for Dictionary.ContainsValue() calls in LINQ queries.

• Added support for string concatenation of mixed types.

• Enabled use of native crypto in libmongocrypt bindings.

• Added support for serialization of Memory and ReadOnlyMemory structs. To learn more about implementing these types, see the Improve Array Serialization Performance section of the Serialization guide.

• Added support for the GCP Identity Provider when using the MONGODB-OIDC authentication mechanism. To learn more, see GCP IMDS in the Enterprise Authentication Mechanisms guide.

• Implemented signing of NuGet packages.

• Implemented read and write retries to other mongos instances when possible.

What's New in 2.25

The 2.25 driver release includes the following new features:

• Added support for the MONGODB-OIDC authentication mechanism and automatic token acquisition for Azure Identity Provider.

• Added the class name to the error message reported when BsonClassMapSerializer cannot locate a matching creator.

• Added a LoggedStages field to surface the MQL executed after performing a LINQ query.

• Added support for overriding the "mongodb" service name with a custom one by using the srvServiceName connection option. To learn more, see the Specify Connection Options guide.

• Improved behavior of bulk write operations to prevent enumerating the requests parameter more than once.

What's New in 2.24

The 2.24 driver release includes the following new features:

• Added the IMongoCollection.DistinctMany() method.

• Added support for the latest optional arguments for the $dateFromString aggregation expression.

• Added support for sorting by score in the $search aggregation stage.

• Added the VectorSearchScore builder for the $vectorSearch aggregation stage.

• Added support for the $in operator in Atlas Search.

• Added the Mql.Exists(), Mql.IsMissing(), and Mql.IsNullOrMissing() methods for LINQ queries.

• Added support for the IComparable.CompareTo() method in LINQ queries.

• Added support for nested calls to the AsQueryable() method to support LINQ queries by the MongoDB Entity Framework Core Provider.

• Added support for TLS 1.3.

• Updated the libmongocrypt package version to 1.8.2.

• Fixed a segfault in Kerberos (libgssapi) on newer Linux distributions.

• Fixed a GridFS bug in which downloading a file caused an error if a larger file with the same ID had also been uploaded.

• The ExceededTimeLimit server error is now retryable for both read and write operations.

• When running within a function-as-a-service (FaaS) environment, such as AWS Lambda, the driver now uses the polling monitoring mechanism.

• To improve MongoDB Atlas Serverless compatibility, the driver now uses OP_MSG for authentication if the server supports it.

What's New in 2.23

The 2.23 driver release includes the following new features:

• Improvements and bug fixes to the LINQ3 integration.

• Added support for aggregation bitwise operators.

• Added support for the $out operator in MongoDB time series collections.

• Added ChangeStreamSplitLargeEvent to handle change stream events greater than 16 MB.

What's New in 2.22

The 2.22 driver release includes the following new features:

• Improvements and bug fixes to the LINQ3 integration.

• Added support for $set and $vectorSearch aggregation stages.

• Added synonym support for Atlas Search.

• Reduced memory allocation when using encryption.

• Added logging messages for server discovery and monitoring (SDAM) events. For more information on these events, see the MongoDB SDAM Logging and Monitoring specification.