Question

using Newtonsoft.Json;

namespace FAL.WebAPI2012.Controllers
{
    public class Person
    {
        public int Id {get;set;}
        public string FirstName {get;set;}
        public string LastName {get;set;}

        [JsonProperty(DefaultValueHandling = DefaultValueHandling.Include, 
            NullValueHandling = NullValueHandling.Include)]
        public DateTime? Dob { get; set; }
    }

    public class TestNullsController : ApiController
    {
        // GET api/<controller>
        public Person Get()
        {
            Person myPerson = new Person() { 
                Dob = null, FirstName = "Adrian", Id=1, LastName="Bobby"
            };

            return myPerson;
        }
    }
}

As you can see, my Dob field is set to null but the result is the following

{ "Id":1, "FirstName":"Adrian", "LastName":"Bobby" }

and Dob is not serialized to null which I need it to be!

(I have tested that JsonProperty is setting other attributes like name and it changes the JSON output perfectly. I just can’t get the nullable property to be serialized.
Also, I have tested Json.Net (see answer below), so my thinking is that web api setup is overriding something somewhere, would be nice to know where).

Answer 1

I received this reply from a member of the web.api folk at Microsoft.

‘You’ll be glad to know this has been fixed since RC:

http://aspnetwebstack.codeplex.com/workitem/243

You can either upgrade to a newer package, or you can override our settings like this:

JsonFormatter.SerializerSettings = new JsonSerializerSettings() { NullValueHandling = NullValueHandling.Include };

Hope that helps’

So, all works with that update.