Using the MongoDB Vector Store connector (Preview)

Overview

The MongoDB Vector Store connector can be used to access and manage data in MongoDB. The connector has the following characteristics.

Getting started

Add the MongoDB Vector Store connector NuGet package to your project.

dotnet add package Microsoft.SemanticKernel.Connectors.MongoDB --prerelease

You can add the vector store to the IServiceCollection dependency injection container using extension methods provided by Semantic Kernel.

using Microsoft.SemanticKernel;

// Using IServiceCollection with ASP.NET Core.
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddMongoDBVectorStore(connectionString, databaseName);

Extension methods that take no parameters are also provided. These require an instance of MongoDB.Driver.IMongoDatabase to be separately registered with the dependency injection container.

using Microsoft.Extensions.DependencyInjection;
using Microsoft.SemanticKernel;
using MongoDB.Driver;

// Using IServiceCollection with ASP.NET Core.
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSingleton<IMongoDatabase>(
    sp =>
    {
        var mongoClient = new MongoClient(connectionString);
        return mongoClient.GetDatabase(databaseName);
    });
builder.Services.AddMongoDBVectorStore();

You can construct a MongoDB Vector Store instance directly.

using Microsoft.SemanticKernel.Connectors.MongoDB;
using MongoDB.Driver;

var mongoClient = new MongoClient(connectionString);
var database = mongoClient.GetDatabase(databaseName);
var vectorStore = new MongoDBVectorStore(database);

It is possible to construct a direct reference to a named collection.

using Microsoft.SemanticKernel.Connectors.MongoDB;
using MongoDB.Driver;

var mongoClient = new MongoClient(connectionString);
var database = mongoClient.GetDatabase(databaseName);
var collection = new MongoDBVectorStoreRecordCollection<Hotel>(
    database,
    "skhotels");

Data mapping

The MongoDB Vector Store connector provides a default mapper when mapping data from the data model to storage.

This mapper does a direct conversion of the list of properties on the data model to the fields in MongoDB and uses MongoDB.Bson.Serialization to convert to the storage schema. This means that usage of the MongoDB.Bson.Serialization.Attributes.BsonElement is supported if a different storage name to the data model property name is required. The only exception is the key of the record which is mapped to a database field named _id, since all MongoDB records must use this name for ids.

Property name override

For data properties and vector properties, you can provide override field names to use in storage that is different to the property names on the data model. This is not supported for keys, since a key has a fixed name in MongoDB.

The property name override is done by setting the BsonElement attribute on the data model properties.

Here is an example of a data model with BsonElement set.

using Microsoft.Extensions.VectorData;

public class Hotel
{
    [VectorStoreRecordKey]
    public ulong HotelId { get; set; }

    [BsonElement("hotel_name")]
    [VectorStoreRecordData(IsFilterable = true)]
    public string HotelName { get; set; }

    [BsonElement("hotel_description")]
    [VectorStoreRecordData(IsFullTextSearchable = true)]
    public string Description { get; set; }

    [BsonElement("hotel_description_embedding")]
    [VectorStoreRecordVector(4, DistanceFunction.CosineSimilarity)]
    public ReadOnlyMemory<float>? DescriptionEmbedding { get; set; }
}

Coming soon

More info coming soon.

Coming soon

More info coming soon.