Question

我正在使用NodaTime和Mongo DB Official Driver的最新版本。我有一个简单的POCO类，它使用NodaTime的ZonedDateTime代替几个属性中的.NET DateTime。

public class MyPOCO
{
    [BsonId]
    [Key]
    public ObjectId SomeId { get; set; }

    public string SomeProperty { get; set; }

    public ZonedDateTime SomeDateTime { get; set; }
}

我可以轻松地将模型放入集合中，但是当我尝试读取查询的模型时，我得到以下MongoDB.Bson.BsonSerializationException：

值类NodaTime.ZonedDateTime无法反序列化

解决/解决此问题的好或最佳做法是什么？

更新

在我的solution发布问题之后，我面临一个可能的新问题......当我查询集合并在我的查询中使用DateTime时，如where SomeDateTime < now' (where现在{{1}可以评估where子句之前的ZonedDateTimeSerializer`。这看起来像是一个很大的性能问题，不是吗？我真的要考虑再次回到BCL DateTime，即使它会受到伤害。

更新2

我正在使用is a variable I create from system time) it seems that each document must be deserialized using my接受我的解决方案，但我对NodaTime与MongoDB的结合感到不舒服，而两者都是很好的个人解决方案。但是他们目前在没有大量操纵的情况下一起工作得不好。

Answer 1

没关系，最后经过多次阅读和实验，终于找到了它。我编写了一个自定义BsonBaseSerializer实现来处理ZonedDateTime。

以下是我ZonedDateTimeSerializer的代码：

/// <summary>
/// Serializer for the Noda
/// </summary>
public class ZonedDateTimeSerializer : BsonBaseSerializer
{
    private static ZonedDateTimeSerializer __instance = new ZonedDateTimeSerializer();

    /// <summary>
    /// Initializes a new instance of the ZonedDateTimeSerializer class.
    /// </summary>
    public ZonedDateTimeSerializer()
    {
    }

    /// <summary>
    /// Gets an instance of the ZonedDateTimeSerializer class.
    /// </summary>
    public static ZonedDateTimeSerializer Instance
    {
        get { return __instance; }
    }

    /// <summary>
    /// Deserializes an object from a BsonReader.
    /// </summary>
    /// <param name="bsonReader">The BsonReader.</param>
    /// <param name="nominalType">The nominal type of the object.</param>
    /// <param name="actualType">The actual type of the object.</param>
    /// <param name="options">The serialization options.</param>
    /// <returns>
    /// An object.
    /// </returns>
    public override object Deserialize(BsonReader bsonReader, Type nominalType, Type actualType, IBsonSerializationOptions options)
    {
        VerifyTypes(nominalType, actualType, typeof(ZonedDateTime));

        var bsonType = bsonReader.GetCurrentBsonType();
        if (bsonType == BsonType.DateTime)
        {
            var millisecondsSinceEpoch = bsonReader.ReadDateTime();
            return new Instant(millisecondsSinceEpoch).InUtc();
        }

        throw new InvalidOperationException(string.Format("Cannot deserialize ZonedDateTime from BsonType {0}.", bsonType));
    }

    /// <summary>
    /// Serializes an object to a BsonWriter.
    /// </summary>
    /// <param name="bsonWriter">The BsonWriter.</param>
    /// <param name="nominalType">The nominal type.</param>
    /// <param name="value">The object.</param>
    /// <param name="options">The serialization options.</param>
    public override void Serialize(BsonWriter bsonWriter, Type nominalType, object value, IBsonSerializationOptions options)
    {
        if (value == null)
            throw new ArgumentNullException("value");

        var ZonedDateTime = (ZonedDateTime)value;
        bsonWriter.WriteDateTime(ZonedDateTime.ToInstant().Ticks);
    }
}

不要忘记注册Serializer。我无法找到如何为每种类型注册Serializer，但您可以按类型注册它，如下所示：

BsonClassMap.RegisterClassMap<MyPOCO>(cm =>
{
    cm.AutoMap();
    cm.GetMemberMap(a => a.SomeDateTime).SetSerializer(ZonedDateTimeSerializer.Instance);
});

希望这有帮助。

Answer 2

这是thmshd类的修改版本，它也存储时区信息：

public class ZonedDateTimeSerializer : IBsonSerializer<ZonedDateTime>
{
    public static ZonedDateTimeSerializer Instance { get; } = new ZonedDateTimeSerializer();

    object IBsonSerializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
    {
        return Deserialize(context, args);
    }

    public void Serialize(BsonSerializationContext context, BsonSerializationArgs args, ZonedDateTime value)
    {
        if (value == null)
            throw new ArgumentNullException(nameof(value));

        var zonedDateTime = value;

        SerializeAsDocument(context, zonedDateTime);
    }

    private static void SerializeAsDocument(BsonSerializationContext context, ZonedDateTime zonedDateTime)
    {
        context.Writer.WriteStartDocument();
        context.Writer.WriteString("tz", zonedDateTime.Zone.Id);
        context.Writer.WriteInt64("ticks", zonedDateTime.ToInstant().Ticks);
        context.Writer.WriteEndDocument();
    }

    public ZonedDateTime Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
    {
        var bsonType = context.Reader.GetCurrentBsonType();

        if (bsonType != BsonType.Document)
        {
            throw new InvalidOperationException($"Cannot deserialize ZonedDateTime from BsonType {bsonType}.");
        }

        context.Reader.ReadStartDocument();
        var timezoneId = context.Reader.ReadString("tz");
        var ticks = context.Reader.ReadInt64("ticks");
        var timezone = DateTimeZoneProviders.Tzdb.GetZoneOrNull(timezoneId);

        if (timezone == null)
        {
            throw new Exception($"Unknown timezone id: {timezoneId}");
        }

        context.Reader.ReadEndDocument();

        return new Instant(ticks).InZone(timezone);
    }

    public void Serialize(BsonSerializationContext context, BsonSerializationArgs args, object value)
    {
        if (value == null)
        {
            throw new ArgumentNullException(nameof(value));
        }

        var zonedDateTime = (ZonedDateTime)value;

        SerializeAsDocument(context, zonedDateTime);
    }

    public Type ValueType => typeof(ZonedDateTime);
}

它可以像这样全球注册：

BsonSerializer.RegisterSerializer(ZonedDateTimeSerializer.Instance);

编辑：使用NodaTimes内置字符串解析可能更好，而不是序列化到子文档。

序列化：

context.Writer.WriteString(ZonedDateTimePattern.CreateWithInvariantCulture("G", DateTimeZoneProviders.Tzdb).Format(zonedDateTime));

反序列化：

        var zonedDateTimeString = context.Reader.ReadString();
        var parseResult = ZonedDateTimePattern.CreateWithInvariantCulture("G", DateTimeZoneProviders.Tzdb)n.Parse(zonedDateTimeString);

        if (!parseResult.Success)
        {
            throw parseResult.Exception;
        }

        return parseResult.Value;

使用MongoDB的NodaTime：值类NodaTime.ZonedDateTime无法反序列化

2 个答案: