.Net: Add support for Guid and ObjectID keys in the MongoDB Connector (#12827)

### Motivation and Context

The MongoDB connector currently only supports string key types.

### Description

Adds support for Guid and ObjectId key types to the MongoDB Connector. 

### Contribution Checklist

- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

---------

Co-authored-by: SergeyMenshykh <68852919+SergeyMenshykh@users.noreply.github.com>
Co-authored-by: westey <164392973+westey-m@users.noreply.github.com>

Author: 3 people

dotnet/src/InternalUtilities/connectors/Memory/MongoDB/MongoModelBuilder.cs

@@ -7,6 +7,7 @@
 using Microsoft.Extensions.AI;
 using Microsoft.Extensions.VectorData;
 using Microsoft.Extensions.VectorData.ProviderServices;
+using MongoDB.Bson;
 using MongoDB.Bson.Serialization.Attributes;
 
 namespace Microsoft.SemanticKernel.Connectors.MongoDB;
@@ -43,9 +44,9 @@ protected override void ProcessTypeProperties(Type type, VectorStoreCollectionDe
 
     protected override bool IsKeyPropertyTypeValid(Type type, [NotNullWhen(false)] out string? supportedTypes)
     {
-        supportedTypes = "string";
+        supportedTypes = "string, Guid, ObjectId";
 
-        return type == typeof(string);
+        return type == typeof(string) || type == typeof(Guid) || type == typeof(ObjectId);
     }
 
     protected override bool IsDataPropertyTypeValid(Type type, [NotNullWhen(false)] out string? supportedTypes)

dotnet/src/VectorData/MongoDB/MongoCollection.cs

@@ -75,6 +75,9 @@ public class MongoCollection<TKey, TRecord> : VectorStoreCollection<TKey, TRecor
     /// <summary>Number of nearest neighbors to use during the vector search.</summary>
     private readonly int? _numCandidates;
 
+    /// <summary>Types of keys permitted.</summary>
+    private readonly Type[] _validKeyTypes = [typeof(string), typeof(Guid), typeof(ObjectId)];
+
     /// <summary>
     /// Initializes a new instance of the <see cref="MongoCollection{TKey, TRecord}"/> class.
     /// </summary>
@@ -103,9 +106,9 @@ internal MongoCollection(IMongoDatabase mongoDatabase, string name, Func<MongoCo
         Verify.NotNull(mongoDatabase);
         Verify.NotNullOrWhiteSpace(name);
 
-        if (typeof(TKey) != typeof(string) && typeof(TKey) != typeof(object))
+        if (!this._validKeyTypes.Contains(typeof(TKey)) && typeof(TKey) != typeof(object))
         {
-            throw new NotSupportedException("Only string keys are supported.");
+            throw new NotSupportedException("Only string, Guid and ObjectID keys are supported.");
         }
 
         options ??= MongoCollectionOptions.Default;
@@ -157,9 +160,9 @@ await this.RunOperationWithRetryAsync(
     /// <inheritdoc />
     public override async Task DeleteAsync(TKey key, CancellationToken cancellationToken = default)
     {
-        var stringKey = this.GetStringKey(key);
+        Verify.NotNull(key);
 
-        await this.RunOperationAsync("DeleteOne", () => this._mongoCollection.DeleteOneAsync(this.GetFilterById(stringKey), cancellationToken))
+        await this.RunOperationAsync("DeleteOne", () => this._mongoCollection.DeleteOneAsync(this.GetFilterById(key), cancellationToken))
             .ConfigureAwait(false);
     }
 
@@ -181,7 +184,7 @@ public override Task EnsureCollectionDeletedAsync(CancellationToken cancellation
     /// <inheritdoc />
     public override async Task<TRecord?> GetAsync(TKey key, RecordRetrievalOptions? options = null, CancellationToken cancellationToken = default)
     {
-        var stringKey = this.GetStringKey(key);
+        Verify.NotNull(key);
 
         var includeVectors = options?.IncludeVectors ?? false;
         if (includeVectors && this._model.EmbeddingGenerationRequired)
@@ -190,7 +193,7 @@ public override Task EnsureCollectionDeletedAsync(CancellationToken cancellation
         }
 
         using var cursor = await this
-            .FindAsync(this.GetFilterById(stringKey), top: 1, skip: null, includeVectors, sortDefinition: null, cancellationToken)
+            .FindAsync(this.GetFilterById(key), top: 1, skip: null, includeVectors, sortDefinition: null, cancellationToken)
             .ConfigureAwait(false);
 
         var record = await cursor.SingleOrDefaultAsync(cancellationToken).ConfigureAwait(false);
@@ -267,7 +270,7 @@ private async Task UpsertCoreAsync(TRecord record, int recordIndex, IReadOnlyLis
         var replaceOptions = new ReplaceOptions { IsUpsert = true };
         var storageModel = this._mapper.MapFromDataToStorageModel(record, recordIndex, generatedEmbeddings);
 
-        var key = storageModel[MongoConstants.MongoReservedKeyPropertyName].AsString;
+        var key = storageModel[MongoConstants.MongoReservedKeyPropertyName];
 
         await this.RunOperationAsync(OperationName, async () =>
             await this._mongoCollection
@@ -673,11 +676,11 @@ private async IAsyncEnumerable<VectorSearchResult<TRecord>> EnumerateAndMapSearc
         }
     }
 
-    private FilterDefinition<BsonDocument> GetFilterById(string id)
+    private FilterDefinition<BsonDocument> GetFilterById(object id)
         => Builders<BsonDocument>.Filter.Eq(document => document[MongoConstants.MongoReservedKeyPropertyName], id);
 
-    private FilterDefinition<BsonDocument> GetFilterByIds(IEnumerable<string> ids)
-        => Builders<BsonDocument>.Filter.In(document => document[MongoConstants.MongoReservedKeyPropertyName].AsString, ids);
+    private FilterDefinition<BsonDocument> GetFilterByIds(IEnumerable<object> ids)
+        => Builders<BsonDocument>.Filter.In(document => document[MongoConstants.MongoReservedKeyPropertyName], ids);
 
     private async Task<bool> InternalCollectionExistsAsync(CancellationToken cancellationToken)
     {
@@ -723,16 +726,5 @@ private async Task<T> RunOperationWithRetryAsync<T>(
             operation,
             cancellationToken).ConfigureAwait(false);
 
-    private string GetStringKey(TKey key)
-    {
-        Verify.NotNull(key);
-
-        var stringKey = key as string ?? throw new UnreachableException("string key should have been validated during model building");
-
-        Verify.NotNullOrWhiteSpace(stringKey, nameof(key));
-
-        return stringKey;
-    }
-
     #endregion
 }

dotnet/src/VectorData/MongoDB/MongoVectorStore.cs

@@ -54,7 +54,7 @@ public MongoVectorStore(IMongoDatabase mongoDatabase, MongoVectorStoreOptions? o
 #pragma warning disable IDE0090 // Use 'new(...)'
     /// <inheritdoc />
     [RequiresDynamicCode("This overload of GetCollection() is incompatible with NativeAOT. For dynamic mapping via Dictionary<string, object?>, call GetDynamicCollection() instead.")]
-    [RequiresUnreferencedCode("This overload of GetCollecttion() is incompatible with trimming. For dynamic mapping via Dictionary<string, object?>, call GetDynamicCollection() instead.")]
+    [RequiresUnreferencedCode("This overload of GetCollection() is incompatible with trimming. For dynamic mapping via Dictionary<string, object?>, call GetDynamicCollection() instead.")]
 #if NET8_0_OR_GREATER
     public override MongoCollection<TKey, TRecord> GetCollection<TKey, TRecord>(string name, VectorStoreCollectionDefinition? definition = null)
 #else

dotnet/test/VectorData/MongoDB.ConformanceTests/CRUD/MongoBatchConformanceTests.cs

@@ -1,12 +1,23 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using MongoDB.Bson;
 using MongoDB.ConformanceTests.Support;
 using VectorData.ConformanceTests.CRUD;
 using Xunit;
 
 namespace MongoDB.ConformanceTests.CRUD;
 
-public class MongoBatchConformanceTests(MongoSimpleModelFixture fixture)
-    : BatchConformanceTests<string>(fixture), IClassFixture<MongoSimpleModelFixture>
+public class MongoBatchConformanceTests_String(MongoSimpleModelFixture<string> fixture)
+    : BatchConformanceTests<string>(fixture), IClassFixture<MongoSimpleModelFixture<string>>
+{
+}
+
+public class MongoBatchConformanceTests_Guid(MongoSimpleModelFixture<Guid> fixture)
+    : BatchConformanceTests<Guid>(fixture), IClassFixture<MongoSimpleModelFixture<Guid>>
+{
+}
+
+public class MongoBatchConformanceTests_ObjectId(MongoSimpleModelFixture<ObjectId> fixture)
+    : BatchConformanceTests<ObjectId>(fixture), IClassFixture<MongoSimpleModelFixture<ObjectId>>
 {
 }

dotnet/test/VectorData/MongoDB.ConformanceTests/CRUD/MongoRecordConformanceTests.cs

@@ -1,12 +1,23 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using MongoDB.Bson;
 using MongoDB.ConformanceTests.Support;
 using VectorData.ConformanceTests.CRUD;
 using Xunit;
 
 namespace MongoDB.ConformanceTests.CRUD;
 
-public class MongoRecordConformanceTests(MongoSimpleModelFixture fixture)
-    : RecordConformanceTests<string>(fixture), IClassFixture<MongoSimpleModelFixture>
+public class MongoRecordConformanceTests_String(MongoSimpleModelFixture<string> fixture)
+    : RecordConformanceTests<string>(fixture), IClassFixture<MongoSimpleModelFixture<string>>
+{
+}
+
+public class MongoRecordConformanceTests_Guid(MongoSimpleModelFixture<Guid> fixture)
+    : RecordConformanceTests<Guid>(fixture), IClassFixture<MongoSimpleModelFixture<Guid>>
+{
+}
+
+public class MongoRecordConformanceTests_ObjectId(MongoSimpleModelFixture<ObjectId> fixture)
+    : RecordConformanceTests<ObjectId>(fixture), IClassFixture<MongoSimpleModelFixture<ObjectId>>
 {
 }

dotnet/test/VectorData/MongoDB.ConformanceTests/Support/MongoSimpleModelFixture.cs

@@ -4,7 +4,8 @@
 
 namespace MongoDB.ConformanceTests.Support;
 
-public class MongoSimpleModelFixture : SimpleModelFixture<string>
+public class MongoSimpleModelFixture<TKey> : SimpleModelFixture<TKey>
+    where TKey : notnull
 {
     public override TestStore TestStore => MongoTestStore.Instance;
 }

dotnet/test/VectorData/MongoDB.ConformanceTests/Support/MongoTestStore.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using Microsoft.SemanticKernel.Connectors.MongoDB;
+using MongoDB.Bson;
 using MongoDB.Driver;
 using Testcontainers.MongoDb;
 using VectorData.ConformanceTests.Support;
@@ -58,6 +59,18 @@ private async Task<MongoClientSettings> StartMongoDbContainerAsync()
         };
     }
 
+    private static readonly string? s_baseObjectId = ObjectId.GenerateNewId().ToString().Substring(0, 14);
+
+    public override TKey GenerateKey<TKey>(int value)
+    {
+        if (typeof(TKey) == typeof(ObjectId))
+        {
+            return (TKey)(object)ObjectId.Parse(s_baseObjectId + value.ToString("0000000000"));
+        }
+
+        return base.GenerateKey<TKey>(value);
+    }
+
     protected override async Task StopAsync()
     {
         if (this._container != null)

dotnet/test/VectorData/MongoDB.UnitTests/MongoVectorStoreTests.cs

@@ -26,7 +26,7 @@ public void GetCollectionWithNotSupportedKeyThrowsException()
         using var sut = new MongoVectorStore(this._mockMongoDatabase.Object);
 
         // Act & Assert
-        Assert.Throws<NotSupportedException>(() => sut.GetCollection<Guid, MongoHotelModel>("collection"));
+        Assert.Throws<NotSupportedException>(() => sut.GetCollection<long, MongoHotelModel>("collection"));
     }
 
     [Fact]