Incorrect serialization in C# using JSON.NET

Question

I am attempting to take an object structured like so

public class Item
{
   public Guid SourceTypeID {get;set;}
   public Guid BrokerID {get;set;}
   public double Latitude {get;set;}
   public double Longitude {get;set;}
   public DateTime TimeStamp {get;set;}
   public object Payload {get;set;}
}

and serialize it with JSON.NET using a call like:

Item expected = new Item()
{
   SourceTypeID = Guid.NewGuid(),
   BrokerID = Guid.NewGuid(),
   Latitude = 33.657145,
   Longitude = -117.766684,
   TimeStamp = DateTime.Now,
   Payload = new byte[]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }
};
string jsonString = JsonConvert.SerializeObject(expected);

The payload member of the Item object will potentially hold any one primitive of a list of C# primitives (plus a few others like Guid), or an array of those types (as in the example, a byte array), or a "flat" object composed of any of those previously listed "primitives" (dynamically created).

When I perform the SerializeObject() call, the string that is produced contains:

{"Payload":"AAECAwQFBgcICQ==","SourceTypeID":"d8220a4b-75b1-4b7a-8112-b7bdae956a45",
 "BrokerID":"951663c4-924e-4c86-a57a-7ed737501dbd",
 "TimeStamp":"\/Date(1328202421559-0600)\/",
 "Latitude":33.657145,"Longitude":-117.766684}

However when I make the deserializing call the item that is produced is partially incorrect

Item actual = JsonConvert.DeserializeObject<Item>(jsonString);

actual.SourceTypeID : {00000000-0000-0000-0000-000000000000}
actual.BrokerID : {951663c4-924e-4c86-a57a-7ed737501dbd}
actual.Latitude : 33.657145;
actual.Longitude : -117.766684;
actual.TimeStamp : {2/2/2012 11:07:01 AM}
actual.Payload : null

The SourceTypeID member (Guid), and the Payload member (object, holding a byte[]), are both incorrect. The serialized string seems to hold the right identity for the guid, but not for the byte array.

I see that an alternate signatureof SerializeObject is

SerializeObject(object value, params JsonConverter[] converters);

Is this the correct way to inform the de/serialization engine about types that it apparently handles wrong? Since I am working with a limited set of "primitives" at the core of my object, if I could create a set of converters for each of those types, would that solve my problem?

I want to avoid reinventing the wheel if possible, as it seems that this would be a problem that has already been handled gracefully, and I'd like to leverage something like that if available.

have you considered creating a List<object[]> and then newing it that way with the individual members then when you deserialize it you could use JsonConvert.DeserializeObject<List<object[]>>(jsonString); something along those lines... — MethodMan
– MethodMan, Commented Feb 2, 2012 at 17:52
I don't think I follow. Does the List<object[]> replace the original Item to be de/serialized? Also, if I tried a deserialize call like you mentioned, wouldn't the jsonString still have a misformed/useless string inside where the byte array should be, as a result of not knowing how to handle an object of type byte[]? — user1185689
– user1185689, Commented Feb 2, 2012 at 17:58
The byte array is (correctly) base64-encoded, which would imply that it is indeed a type the library knows to handle. Also odd that one of the GUID's would come back correctly and the other wouldn't. — millimoose
– millimoose, Commented Feb 2, 2012 at 17:59
I am going to test your example I also removed your ; and replaced it with , in your original code sample because like it was it should not have compiled — MethodMan
– MethodMan, Commented Feb 2, 2012 at 18:00
DJ, thanks, that wasn't copied code. I just recreated it for the sake of the example. Those were indeed supposed to be commas. — user1185689
– user1185689, Commented Feb 2, 2012 at 18:10

James Newton-King · Accepted Answer · 2012-02-03 03:00:49Z

4

Payload will be deserialized as a string unless you place a [JsonProperty] attribute with TypeNameHandling enabled on it, otherwise the deserializer won't know what to deserialize it as.

I haven't been able to duplicate the problem you got with some properties being null using the latest source code at http://json.codeplex.com/SourceControl/list/changesets

answered Feb 3, 2012 at 3:00

James Newton-King

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Randolpho · Accepted Answer · 2012-02-02 18:18:30Z

1

This appears to be an actual bug in JSON.NET.

It's not idea, but a workaround might be to have a two-stage serialization. The first, the object that actually gets serialized to/from JSON, would consist only of fields/properties with string type. The second object (the one your server-side code would use) would be an object that is converted to strong types manually.

Not ideal, but possible. Additonally, you could consider using the DataContractJsonSerializer, which does a pretty good job of handling byte arrays and guids IME. Dates are still pretty sucky, but that's mostly the fault of Javascript.

answered Feb 2, 2012 at 18:18

Randolpho

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1 Comment

user1185689 Over a year ago

Thanks for pointing me at the DataContractJsonSerializer. I'll look into it as a serializing solution.

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