.Net MongoDB批量修改集合中子集合的字段

环境：.Net Core 3.1 (需要导入.Net MongoDB的驱动)

模型

   /// <summary>
    /// 收藏
    /// </summary>
    public class CtStreetFollow
    {
        /// <summary>
        /// 收藏人编号
        /// </summary>
        public long Id { get; set; }

        /// <summary>
        /// 收藏
        /// </summary>
        public List<StreetFollow> StreetFollows { get; set; }
    }

 /// <summary>
    /// 收藏
    /// </summary>
    public class StreetFollow
    {
        /// <summary>
        /// 尾货编号
        /// </summary>
        public long StreetId { get; set; }

        /// <summary>
        /// 卖家编号
        /// </summary>
        public long UserId { get; set; }

        /// <summary>
        /// 置顶
        /// </summary>
        public int Top { get; set; }
    }

代码：

public async Task SetTop(long userId, List<long> productIds, bool isTop)
{
var bson = MakeUpdateParam("$set", nameof(CtStreetFollow.StreetFollows),
new[]
{
new KeyValuePair<string, object>(nameof(StreetFollow.Top),
),
});
await UpdateData(nameof(CtStreetFollow.StreetFollows), productIds, "$in", _collection, bson);
}

/// <summary>
/// 用户数据修改统一更新
/// </summary>
/// <returns></returns>
internal async Task UpdateData(string arrayName, List<long> productIds, string myOperator, IMongoCollection<CtStreetFollow> col, BsonDocument bson)
{
var filters = Builders<CtStreetFollow>.Filter.ElemMatch(arrayName, Builders<StreetFollow>.Filter.In(p => p.StreetId, productIds));
await col.UpdateManyAsync(filters, bson, new UpdateOptions
{
ArrayFilters = new List<ArrayFilterDefinition> { new BsonDocumentArrayFilterDefinition<CtStreetFollow>(MakeSimpleUpdateArrayFilter(nameof(StreetFollow.StreetId), productIds, myOperator))
}
});
}

/// <summary>
/// 合成bson
/// </summary>
/// <returns></returns>
public BsonDocument MakeUpdateParam(string myOperator, string arrayField, KeyValuePair<string, object>[] innerFvs)
{

return new BsonDocument(new Dictionary<string, object>
{
{myOperator, new BsonDocument(innerFvs.ToDictionary(p=>$"{arrayField}.$[elem].{p.Key}", p=>p.Value))}
});

}

/// <summary>
/// 构造简单的数组过滤BSON
/// 支持单字段，简单操作符
/// 数组子项别买
/// </summary>
/// <param name="field">数组子项中的字段</param>
/// <param name="value">字段值</param>
/// <param name="myOperator">简单操作符</param>
/// <returns></returns>
public BsonDocument MakeSimpleUpdateArrayFilter(string field, object value, string myOperator)
{

return new BsonDocument(new Dictionary<string, object>
{
{$"elem.{field}", new BsonDocument(new Dictionary<string, object>
{
{myOperator, value}
})}
});
}