SemanticKernel impl doesn't support collection metadata. Need changes when moved...

Bắt đầu với src/Chroma/ChromaVectorCollection.cs và phần triển khai được liên kết, tập trung vào mã đã được chú thích của CollectionMetadata và SelectRelevanceScoreFn. Kiểm tra các Semantic Kernel ChromaMemoryStore APIs hiện có để xác định cách lấy metadata của collection và các loại khoảng cách; công việc được xem là hoàn thành khi hành vi metadata dự kiến và việc xử lý các khoảng cách được hỗ trợ đã được triển khai mà không dựa trên các giả định đang được hardcode hiện tại.

private Dictionary<string, string> CollectionMetadata { get; } = [];

{

distanceType = value;

}

https://github.com/tryAGI/LangChain.Databases/blob/709070b0226b59fe8eef116395b0e4ad1bd5df97/src/Chroma/src/ChromaVectorCollection.cs#L19

using System.Text.Json;
using System.Text.Json.Serialization;
using LangChain.Databases.JsonConverters;
using Microsoft.SemanticKernel.Connectors.Chroma;
using Microsoft.SemanticKernel.Memory;

namespace LangChain.Databases.Chroma;

/// <summary>
/// ChromaDB vector collection.
/// According: https://api.python.langchain.com/en/latest/_modules/langchain/vectorstores/chroma.html
/// </summary>
public class ChromaVectorCollection(
    ChromaMemoryStore store,
    string name = VectorCollection.DefaultName,
    string? id = null)
    : VectorCollection(name, id), IVectorCollection
{
    // TODO: SemanticKernel impl doesn't support collection metadata. Need changes when moved to another impl
    //private Dictionary<string, string> CollectionMetadata { get; } = [];

    /// <inheritdoc />
    public async Task<Vector?> GetAsync(string id, CancellationToken cancellationToken = default)
    {
        var record = await store.GetAsync(Name, id, withEmbedding: true, cancellationToken: cancellationToken).ConfigureAwait(false);
        if (record == null)
        {
            return null;
        }

        var text = record.Metadata.Text;
        var metadata = DeserializeMetadata(record.Metadata);

        return new Vector
        {
            Text = text,
            Metadata = metadata,
        };
    }

    /// <inheritdoc />
    public async Task<bool> DeleteAsync(
        IEnumerable<string> ids,
        CancellationToken cancellationToken = default)
    {
        await store.RemoveBatchAsync(Name, ids, cancellationToken).ConfigureAwait(false);

        return true;
    }

    private static float SelectRelevanceScoreFn(float distance)
    {
        //const string distanceKey = "hnsw:space";

        var distanceType = "l2";
        //if (CollectionMetadata.TryGetValue(distanceKey, out var value))
        //{
        //    distanceType = value;
        //}

        return distanceType switch
        {
            "cosine" => RelevanceScoreFunctions.Cosine(distance),
            "l2" => RelevanceScoreFunctions.Euclidean(distance),
            "ip" => RelevanceScoreFunctions.MaxInnerProduct(distance),

            _ => throw new ArgumentException(
                $@"No supported normalization function for distance metric of type: {distanceType}.
                Consider providing relevance_score_fn to Chroma constructor.")
        };
    }

    /// <inheritdoc />
    public async Task<IReadOnlyCollection<string>> AddAsync(
        IReadOnlyCollection<Vector> items,
        CancellationToken cancellationToken = default)
    {
        items = items ?? throw new ArgumentNullException(nameof(items));

        var records = new MemoryRecord[items.Count];
        for (var index = 0; index < items.Count; index++)
        {
            var item = items.ElementAt(index);

            // TODO: check: description, externalSourceName, key
            records[index] = new MemoryRecord
            (
                new MemoryRecordMetadata
                (
                    isReference: false,
                    id: item.Id,
                    text: item.Text,
                    description: string.Empty,
                    externalSourceName: string.Empty,
                    additionalMetadata: SerializeMetadata(item.Metadata ?? new Dictionary<string, object>())
                ),
                new ReadOnlyMemory<float>(item.Embedding ?? []),
                key: null
            );
        }

        var resultIds = new List<string>(items.Count);
        var resultIdsIterator = store.UpsertBatchAsync(Name, records, cancellationToken);
        await foreach (var item in resultIdsIterator.ConfigureAwait(false))
        {
            resultIds.Add(item);
        }

        return resultIds;
    }

    /// <inheritdoc />
    public async Task<VectorSearchResponse> SearchAsync(
        VectorSearchRequest request,
        VectorSearchSettings? settings = default,
        CancellationToken cancellationToken = default)
    {
        request = request ?? throw new ArgumentNullException(nameof(request));
        settings ??= new VectorSearchSettings();

        settings.RelevanceScoreFunc ??= SelectRelevanceScoreFn;

        var matches = await store
            .GetNearestMatchesAsync(
                collectionName: Name,
                embedding: new System.ReadOnlyMemory<float>(request.Embeddings.First()),
                limit: settings.NumberOfResults,
                cancellationToken: cancellationToken)
            .ToListAsync(cancellationToken)
            .ConfigureAwait(false);

        return new VectorSearchResponse
        {
            Items = matches
                .Select(record =>
                {
                    var text = record.Item1.Metadata.Text;
                    var metadata = DeserializeMetadata(record.Item1.Metadata);

                    return new Vector
                    {
                        Id = record.Item1.Metadata.Id,
                        Text = text,
                        Metadata = metadata,
                        Embedding = record.Item1.Embedding.ToArray(),
                        Distance = (float)record.Item2
                    };
                })
                .ToArray(),
        };
    }

    /// <inheritdoc />
    public Task<bool> IsEmptyAsync(CancellationToken cancellationToken = default)
    {
        throw new NotImplementedException();
    }

    private static string SerializeMetadata(IReadOnlyDictionary<string, object> metadata)
    {
        return JsonSerializer.Serialize(metadata, SourceGenerationContext.Default.IReadOnlyDictionaryStringObject);
    }

    private static IReadOnlyDictionary<string, object> DeserializeMetadata(MemoryRecordMetadata metadata)
    {
        return JsonSerializer.Deserialize(metadata.AdditionalMetadata, SourceGenerationContext.Default.IReadOnlyDictionaryStringObject)
               ?? new Dictionary<string, object>();
    }
}

[JsonSourceGenerationOptions(Converters = [typeof(ObjectAsPrimitiveConverter)])]
[JsonSerializable(typeof(IReadOnlyDictionary<string, object>))]
[JsonSerializable(typeof(double))]
[JsonSerializable(typeof(float))]
[JsonSerializable(typeof(int))]
[JsonSerializable(typeof(decimal))]
internal sealed partial class SourceGenerationContext : JsonSerializerContext;