为什么DateTime.MinValue不UTC时区提前进行序列化？ [英] Why can DateTime.MinValue not be serialized in timezones ahead of UTC?

问题描述

我遇到一个WCF REST服务问题。该线对象，我尝试返回具有一定的属性没有设置，导致DateTime.MinValue为DateTime类型的属性。该服务将返回一个空文件（与HTTP状态200 ???）。当我尝试调用JSON序列化自己，即抛出的异常是：

SerializationException：DateTime值是比DateTime.MaxValue或更大比DateTime.MinValue当转换为UTC较小不能被序列化到JSON。

这可以通过在控制台中运行以下代码复制应用程序：

  DataContractJsonSerializer SER =新DataContractJsonSerializer（typeof运算（DATETIME））; 
 MemoryStream的M =新的MemoryStream（）; 
 DateTime的DT = DateTime.MinValue; 
 
 //抛出SerializationException在我的时区
 ser.WriteObject（男，DT）; 
串JSON = Encoding.ASCII.GetString（m.GetBuffer（））; 
 Console.WriteLine（JSON）; 
  

为什么这种行为？我认为这是关系到我的时区（GMT + 1）。由于DateTime.MinValue是默认值（日期时间），我希望这能没有问题被序列化。

如何让我的REST服务的行为有什么建议？我不想改变我的DataContract。

解决方案

主要的问题是 DateTime.MinValue 的 DateTimeKind.Unspecified 的那种。它被定义为：

<预类=郎-CS prettyprint-覆盖> MINVALUE =新日期时间（0L，DateTimeKind.Unspecified）;


但是，这不是一个真正的问题，这个定义序列化过程中带来的问题。 JSON序列化的DateTime通过完成：

<预类=郎-CS prettyprint-覆盖> System.Runtime.Serialization.Json.JsonWriterDelegator.WriteDateTime（日期时间值）


不幸的是它被定义为：

<前类=郎-CS prettyprint-覆盖> ...

如果（value.Kind！= DateTimeKind.Utc）
{
长NUM = value.Ticks - TimeZone.CurrentTimeZone.GetUtcOffset（值）.Ticks;
如果（（NUM> DateTime.MaxValue.Ticks）||（NUM< D​​ateTime.MinValue.Ticks））
{
掷DiagnosticUtility.ExceptionUtility.ThrowHelperError（XmlObjectSerializer.CreateSerializationException（SR .GetString（JsonDateTimeOutOfRange），新ArgumentOutOfRangeException（值）））;
}
}

...


所以它并没有考虑到未指定，将其视为本地。为了避免这种情况，你可以定义自己的常量：

<预类=郎-CS prettyprint-覆盖> MinValueUtc =新日期时间（0L，DateTimeKind 。世界标准时间）;


或

<预类=郎-CS prettyprint-覆盖> MinValueUtc = DateTime.MinValue.ToUniversalTime（）;


看起来怪异，当然，但它有助于。

I am experiencing issues with a WCF REST service. The wire object that I try to return has certain properties not set, resulting in DateTime.MinValue for properties of type DateTime. The service returns an empty document (with HTTP status 200 ???). When I try to call JSON serialization myself, the exception that is thrown is:

SerializationException: DateTime values that are greater than DateTime.MaxValue or smaller than DateTime.MinValue when converted to UTC cannot be serialized to JSON.

This can be reproduced by running the following code in a console app:

DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(DateTime));
MemoryStream m = new MemoryStream();
DateTime dt = DateTime.MinValue;

// throws SerializationException in my timezone
ser.WriteObject(m, dt);
string json = Encoding.ASCII.GetString(m.GetBuffer());
Console.WriteLine(json);

Why is this behaviour? I think it is related to my timezone (GMT+1). As DateTime.MinValue is default(DateTime), I would expect that this can be serialized without problems.

Any tips on how to make my REST service behave? I don't want to change my DataContract.

解决方案

The main problem is DateTime.MinValue has DateTimeKind.Unspecified kind. It is defined as:

MinValue = new DateTime(0L, DateTimeKind.Unspecified);

But this is not a real problem, this definition leads to problem during serialization. JSON DateTime serialization done through:

System.Runtime.Serialization.Json.JsonWriterDelegator.WriteDateTime(DateTime value)

Unfortunately it is defined as:

...

if (value.Kind != DateTimeKind.Utc)
{
    long num = value.Ticks - TimeZone.CurrentTimeZone.GetUtcOffset(value).Ticks;
    if ((num > DateTime.MaxValue.Ticks) || (num < DateTime.MinValue.Ticks))
    {
        throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(XmlObjectSerializer.CreateSerializationException(SR.GetString("JsonDateTimeOutOfRange"), new ArgumentOutOfRangeException("value")));
    }
}

...

So it doesn't take into account Unspecified and treats it as Local. To avoid this situation you can define your own constant:

MinValueUtc = new DateTime(0L, DateTimeKind.Utc);

or

MinValueUtc = DateTime.MinValue.ToUniversalTime();

It looks weird of course, but it helps.

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