Json.Net messes up timezones for DateTimeOffset when serializing

Question

I have looked at a lot of related questions but none of them seem to be working for me.

I'm trying to serialize everything in UTC. Here's my code:

class Class1
{
    static void Main()
    {
        Class2 foo = new Class2();
        JObject json = JObject.Parse(JsonConvert.SerializeObject(foo, new JsonSerializerSettings()
        {
            DateParseHandling = DateParseHandling.DateTimeOffset,
            DateFormatHandling = DateFormatHandling.IsoDateFormat,
            DateTimeZoneHandling = DateTimeZoneHandling.Utc
        }));

        Console.WriteLine(json.ToString());

        Console.Read();
    }
}

class Class2
{
    public DateTimeOffset time = new DateTimeOffset(new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddTicks(14663484000000000));

    public DateTimeOffset time2 = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddTicks(14663484000000000);

    public DateTime time3 = new DateTime(14663484000000000);
}

Here's the output:

{
    "time": "2016-06-19T08:00:00-07:00",
    "time2": "2016-06-19T08:00:00-07:00",
    "time3": "0047-06-20T15:00:00Z"
}

Here's the output I'm trying to get:

{
    "time": "2016-06-19T15:00:00+00:00",
    "time2": "2016-06-19T15:00:00+00:00",
    "time3": "0047-06-20T15:00:00+00:00"
}

As you can see, the DateTimeOffset properties are not converted at all. The DateTime is, but the timezone is indicated using Z whereas I'm trying to use +00:00.

Lucilla

Why are you serializing your foo to a JSON string, then parsing the string to a JToken hierarchy, then re-serializing the hierarchy to a string to reproduce your problem? If you just serialize foo to a string directly the time zone information is correct, yes? – Godber

@Godber I want to add some properties to the serialized JSON, but I took that part out when trying to figure this out. I still need it in the end. – Lucilla

Answer 1

In your code, you are doing the following:

1. Serializing an instance of Class2 to a JSON string using specific DateTime-related serialization settings.
2. Deserializing to a JToken hierarchy without using those settings.
3. (Making additional modifications to the hierarchy - not shown.)
4. Serializing the JToken hierarchy to a final string (via json.ToString()) again without using those settings.

When you do, formatting settings for dates chosen in step #1 get lost.

To solve this, you need to apply the settings every time you serialize from or to a JSON string representation, since, as explained in this documentation page, JSON does not have an "official" format for dates. Because of this, Json.NET applies heuristics for recognizing and formatting dates whenever it converts from and to a JSON string representation - which you are doing not once but thrice.

You could accomplish this by doing:

var settings = new JsonSerializerSettings()
{
    DateParseHandling = DateParseHandling.DateTimeOffset,
    DateFormatHandling = DateFormatHandling.IsoDateFormat,
    DateTimeZoneHandling = DateTimeZoneHandling.Utc
};

// Generate initial serialization
var initialString = JsonConvert.SerializeObject(foo, settings);

// Parse back to JToken
var json = JsonConvert.DeserializeObject<JObject>(initialString, settings);

// Make modifications as required
// json["foo"] = "bar";

// Generate final JSON.
var finalString = JsonConvert.SerializeObject(json, Formatting.Indented, settings);

To improve efficiency, you could use JToken.FromObject() (or JObject.FromObject() if you prefer) to generate the JToken hierarchy without needing to create and parse an initial string representation:

var settings = new JsonSerializerSettings()
{
    DateParseHandling = DateParseHandling.DateTimeOffset,
    DateFormatHandling = DateFormatHandling.IsoDateFormat,
    DateTimeZoneHandling = DateTimeZoneHandling.Utc
};

var json = JToken.FromObject(foo, JsonSerializer.CreateDefault(settings));

// Make modifications as required
// json["foo"] = "bar";

// Generate final JSON.
var finalString = JsonConvert.SerializeObject(json, Formatting.Indented, settings);

Note, however, that Json.NET will output a UTC DateTime in the format "0047-06-20T15:00:00Z" rather than "2016-06-19T15:00:00+00:00" for reasons explained here. If you need your UTC DateTime properties to be serialized in DateTimeOffset format you might need to use a custom converter.

Godber