c# – json.net datetime的序列化/反序列化’未指定’

发布时间：2020-12-15 08:00:05 所属栏目：百科来源：网络整理

导读：在常规的.net中, 如果我们有一个DateTimeKind.Unspecified的时间如果我们转换ToLocal – 它假定转换时输入日期是UTC. 如果我们转换为ToUniversal – 它假定转换时输入日期是本地的但是,在JSON.Net中,如果我们在JSON.Net中的字符串日期未指定,它似乎没有这

在常规的.net中,
如果我们有一个DateTimeKind.Unspecified的时间
如果我们转换ToLocal – 它假定转换时输入日期是UTC.
如果我们转换为ToUniversal – 它假定转换时输入日期是本地的

但是,在JSON.Net中,如果我们在JSON.Net中的字符串日期未指定,它似乎没有这个逻辑？看看我下面的测试用例 – 我做错了吗？或者这是设计？或JSON.Net中的错误？
谢谢！

// TODO: This Fails with output
    //      date string: "2014-06-02T21:00:00.0000000"
    //      date serialized: 2014-06-02T21:00:00.0000000Z
    //      Expected date and time to be <2014-06-03 04:00:00>,but found <2014-06-02 21:00:00>.
    [TestMethod]
    public void NEW_Should_deserialize_unspecified_datestring_to_utc_date()
    {
        string dateString = ""2014-06-02T21:00:00.0000000"";
        DateTime dateRaw = new DateTime(2014,6,2,21,DateTimeKind.Unspecified);
        DateTime dateRawAsUtc = new DateTime(2014,3,4,DateTimeKind.Utc);
        dateRawAsUtc.Should().Be(dateRaw.ToUniversalTime());

        JsonSerializerSettings settings = new JsonSerializerSettings();
        settings.DateTimeZoneHandling = DateTimeZoneHandling.Utc;
        settings.DateFormatHandling = DateFormatHandling.IsoDateFormat;
        DateTime dateSerialized = JsonConvert.DeserializeObject<DateTime>(dateString,settings);                

        Console.WriteLine("date string: " + dateString);
        Console.WriteLine("date serialized: " + dateSerialized.ToString("o"));

        dateSerialized.Kind.Should().Be(DateTimeKind.Utc); 
        dateSerialized.Should().Be(dateRaw.ToUniversalTime());
        dateSerialized.Should().Be(dateRawAsUtc);
    }

    // TODO: This Fails with output
    //      date string: "2014-06-02T21:00:00.0000000"
    //      date serialized: 2014-06-02T21:00:00.0000000-07:00
    //      Expected date and time to be <2014-06-02 14:00:00>,but found <2014-06-02 21:00:00>.
    [TestMethod]
    public void NEW_Should_deserialize_unspecified_datestring_to_local_date()
    {
        string dateString = ""2014-06-02T21:00:00.0000000"";
        DateTime dateRaw = new DateTime(2014,DateTimeKind.Unspecified);
        DateTime dateRawAsLocal = new DateTime(2014,14,DateTimeKind.Local);
        dateRawAsLocal.Should().Be(dateRaw.ToLocalTime());

        JsonSerializerSettings settings = new JsonSerializerSettings();
        settings.DateTimeZoneHandling = DateTimeZoneHandling.Local;
        settings.DateFormatHandling = DateFormatHandling.IsoDateFormat;
        DateTime dateSerialized = JsonConvert.DeserializeObject<DateTime>(dateString,settings);

        Console.WriteLine("date string: " + dateString);
        Console.WriteLine("date serialized: " + dateSerialized.ToString("o"));

        dateSerialized.Kind.Should().Be(DateTimeKind.Local);
        dateSerialized.Should().Be(dateRaw.ToLocalTime());
        dateSerialized.Should().Be(dateRawAsLocal);
    }

    [TestMethod]
    public void NEW_Should_deserialize_unspecified_datestring_to_unspecified_date() 
    {
        string dateString = ""2014-06-02T21:00:00.0000000""; // unspecified,does not have the 'Z'
        DateTime dateRaw = new DateTime(2014,DateTimeKind.Unspecified);

        JsonSerializerSettings settings = new JsonSerializerSettings();
        settings.DateTimeZoneHandling = DateTimeZoneHandling.Unspecified;
        settings.DateFormatHandling = DateFormatHandling.IsoDateFormat;
        DateTime dateSerialized = JsonConvert.DeserializeObject<DateTime>(dateString,settings);                

        Console.WriteLine("date string: " + dateString);
        Console.WriteLine("date serialized: " + dateSerialized.ToString("o"));
        dateSerialized.Kind.Should().Be(DateTimeKind.Unspecified); 
        dateSerialized.Should().Be(dateRaw);
    }

解决方法

我不是百分百肯定你在这里寻找什么,但我认为假设JSON.Net在没有一点帮助的情况下满足你的所有需求是不安全的.如 Mr. Newton says：

Dates in JSON are hard.

首先要确定是否要支持接受未指定的日期,或者是否要假设所有传入的日期都是通用的,即使它们缺少尾随的Z.

如果您假设所有传入日期都是通用的,您可以看看它们是否有尾随Z,如果没有,则添加它(不完全是生产代码,但您明白了)：

if (!dateString.EndsWith("Z"",StringComparison.InvariantCultureIgnoreCase))
{
    dateString = dateString.Substring(0,dateString.LastIndexOf(""",StringComparison.InvariantCultureIgnoreCase)) + "Z"";
}

假设的这种变化确实要求将您测试的日期修改为Utc.

如果您不想假定传入日期是通用的,而是将它们视为未指定,则需要通过替换来更改转换传入JSON的方式：

JsonSerializerSettings settings = new JsonSerializerSettings();
settings.DateTimeZoneHandling = DateTimeZoneHandling.Utc;
settings.DateFormatHandling = DateFormatHandling.IsoDateFormat;
DateTime dateSerialized = JsonConvert.DeserializeObject<DateTime>(dateString,settings);

有：

var oConverter = new Newtonsoft.Json.Converters.IsoDateTimeConverter();
DateTime dateSerialized = JsonConvert.DeserializeObject<DateTime>(dateString,oConverter);

这将导致一个未指定的日期与dateString完全匹配.这是你的助手发挥作用的地方：

if (dateSerialized.Kind == DateTimeKind.Unspecified)
{
    dateSerialized = dateSerialized.ToUniversalTime();
}

这意味着完整的,修订的第一个测试将如下所示,它将通过：

string dateString = ""2014-06-02T21:00:00.0000000"";
    DateTime dateRaw = new DateTime(2014,DateTimeKind.Unspecified);
    DateTime dateRawAsUtc = new DateTime(2014,DateTimeKind.Utc);
    dateRawAsUtc.Should().Be(dateRaw.ToUniversalTime());

    var oConverter = new Newtonsoft.Json.Converters.IsoDateTimeConverter();
    DateTime dateSerialized = JsonConvert.DeserializeObject<DateTime>(dateString,oConverter);
    if (dateSerialized.Kind == DateTimeKind.Unspecified)
    {
        dateSerialized = dateSerialized.ToUniversalTime();
    }

    Console.WriteLine("date string: " + dateString);
    Console.WriteLine("date serialized: " + dateSerialized.ToString("o"));

    dateSerialized.Kind.Should().Be(DateTimeKind.Utc); 
    dateSerialized.Should().Be(dateRaw.ToUniversalTime());
    dateSerialized.Should().Be(dateRawAsUtc);

（编辑：李大同）

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