NewtonSoft.Json自定义JsonConverter反序列化到DateTime不工作 [英] NewtonSoft.Json custom JsonConverter deserialize to DateTime not working

问题描述

我正在尝试反序列化 Unix时间戳到 DateTime 。在我的情况下，我需要做更多的检查，然后才能从时间戳记将属性设置为DateTime。如果我从 Newtonsoft.Json 中使用 DateTime ，则将其反序列化为 UTC 时间，我需要反序列化到特定的时区

I am trying to deserialize a Unix timestamp to a DateTime. In my case, I need to do much more checks before I can set a property to DateTime from a timestamp. If I use DateTime from Newtonsoft.Json it deserializes it to UTC time and I need to deserialize it to a specific timezone

问题是我无法获得正确的时间。看起来我的字符串 long 解析失败。如果我可以获得 long unix时间戳，我可以得到其余的逻辑工作

The problem is that I am not able to get the correct time. It seems like my string to long parsing is failing. If I can get the long unix timestamp, I can get the rest of the logic working

我有一个类命名为警报

class Alert
{
    // Some properties

    [JsonConverter(typeof(UnixTimestampJsonConverter))]
    public DateTime Created { get; set; }

    // Some more properties
}

UnixTimestampJsonConverter 是

class UnixTimestampJsonConverter : JsonConverter
{
    // Other override methods

    public override object ReadJson (JsonReader reader, Type objectType, 
        object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.EndObject)
            return null;

        if (reader.TokenType == JsonToken.StartObject) {
            long instance = serializer.Deserialize<long> (reader);
            return TimeUtils.GetCustomDateTime (instance);
        }

        return null;
    }
}

其中 TimeUtils.GetCustomDateTime实例）使用长的unixtimestamp并将其转换为特定时区的DateTime对象。

Where TimeUtils.GetCustomDateTime (instance) takes the long unixtimestamp and converts it into DateTime object of specific timezone.

我在一个PCL库中具有个人资料78 ，所以我有限制访问 System.TimeZoneInfo ，我正在使用PCL版本的 NodaTime 其他时区计算。

I am in a PCL library with Profile 78, so I have limited access to System.TimeZoneInfo and I am using PCL version of NodaTime for other timezone calculations.

如果有人有兴趣，这是Github上的项目 - MBTA Sharp

In case anyone is interested, this is the project on Github - MBTA Sharp

推荐答案

我很确定你需要做的是调用 serializer.Deserialize 。这样做会提高读者的正确性，你不应该做任何其他事情：

I'm pretty sure all you need to do is call serializer.Deserialize. Doing this will advance the reader correctly and you shouldn't need to do anything else:

public class UnixTimestampJsonConverter : JsonConverter
{
    public override object ReadJson(
        JsonReader reader,
        Type objectType,
        object existingValue,
        JsonSerializer serializer)
    {
        long ts = serializer.Deserialize<long>(reader);

        return TimeUtils.GetMbtaDateTime(ts);
    }

    public override  bool CanConvert(Type type)
    {
        return typeof(DateTime).IsAssignableFrom(type);
    }

    public override void WriteJson(
        JsonWriter writer,
        object value,
        JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }

    public override bool CanRead
    { 
        get { return true; } 
    }
}

示例： a href =https://dotnetfiddle.net/Fa8Zis =noreferrer> https://dotnetfiddle.net/Fa8Zis

Example: https://dotnetfiddle.net/Fa8Zis

这篇关于NewtonSoft.Json自定义JsonConverter反序列化到DateTime不工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！