无法从IMongoQueryable mongodb c#驱动程序linq语句上的GroupBy中的组中获取组项目

var collection = database.GetCollection<BsonDocument>("yourCollection");

var pipeline = new BsonDocument[]
{
    new BsonDocument("$group", new BsonDocument
    {
        { "_id", "$yourGroupKey" },
        { "items", new BsonDocument("$push", "$yourField") }
    }),
    new BsonDocument("$project", new BsonDocument
    {
        { "_id", 0 },
        { "groupKey", "$_id" },
        { "groupItems", "$items" }
    })
};

var result = collection.Aggregate<BsonDocument>(pipeline).ToList();