json.net序列化/反序列化datetime'未指定'

Question

在常规.net中,如果我们有一个具有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, 0, 0, 0, DateTimeKind.Unspecified);
        DateTime dateRawAsUtc = new DateTime(2014, 6, 3, 4, 0, 0, 0, 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, 6, 2, 21, 0, 0, 0, DateTimeKind.Unspecified);
        DateTime dateRawAsLocal = new DateTime(2014, 6, 2, 14, 0, 0, 0, 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, 6, 2, 21, 0, 0, 0, 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);
    }

Answer 1

我不能 100% 确定您在这里寻找什么，但我认为假设 JSON.Net 无需一点帮助就能满足您的所有需求是不安全的。正如牛顿先生所说：

JSON 中的日期很难。

第一件事是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，您只需查看它们是否有尾随 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\"";
}

这种假设的变化确实需要将您测试的日期修改为 Utc。

如果您不想假设传入日期是通用的，而是将它们视为未指定的，则需要通过替换以下内容来更改转换传入 JSON 的方式：

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

和：

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

这将导致与 dateString 完全匹配的未指定日期。这是您的帮助之手发挥作用的地方：

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

这意味着完整的、修订后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, 6, 2, 21, 0, 0, 0, DateTimeKind.Unspecified);
    DateTime dateRawAsUtc = new DateTime(2014, 6, 3, 4, 0, 0, 0, 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);