DefaultValueHandling not honored in Json.NET 4.5

Question

I'm using JSON.NET 4.5 and following this blog post, trying to get my user objects to serialize correctly.

I've been beating my head against the wall for hours; no matter what I do, I cannot get Json.NET to ignore ints when they are set to the "default unitialized value for that value type", aka 0.

[DataContract]    
public class User
{
    [DataMember]
    public int Id { get; set; }

    [DataMember]
    public string Name{ get; set; }

    [DataMember]
    public string Email{ get; set; }        
}

Here's the call to serialize it:

var user = new User()
{
    Id = 0,
    Name = "John Doe",
    Email = null
}

string body = JsonConvert.SerializeObject(user, Formatting.Indented, new JsonSerializerSettings()
{
    DefaultValueHandling = DefaultValueHandling.Ignore
});

The resulting JSON is:

{
    "Id": 0,
    "Name": "John Doe"
}

Email is omitted because it is null. Id should be omitted because it is 0. I have also tried explicitly setting the [DefaultValue(0)] attribute on Id, to no effect.

Am I doing something wrong, or is this a bug?

Update

After taking another look, DefaultValueAtribute is being honored for ints. So this code will result Ids of 0 not being serialized.

[DataContract]    
public class User
{
    [DataMember]
    [DefaultValue(0)]
    public int Id { get; set; }

    [DataMember]
    public string Name{ get; set; }

    [DataMember]
    public string Email{ get; set; }        
}

Not the stated behavior, but at least it allows me to get on with my life.

Answer 1

It appears to be a bug. According to the example from documentation a DefaultValueAttribute shouldn't be required. This is useful e.g. when you can't edit the type you're serializing.

I made an issue in Github for it, along with a patch/hack (against 4.5r8).