Question

I have a action which returns an JsonResult for an object of a particular class. I have decorated the properties of this class with some attrib to avoid null fields. Class definition is:

    private class GanttEvent
    {
        public String name { get; set; }

        [JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
        public String desc { get; set; }

        [JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
        public List<GanttValue> values { get; set; }
    }

And in my Action i use an object

    var res = new List<GanttEvent>();

which I return using:

    return Json(res, JsonRequestBehavior.AllowGet);

Unfortunatelly, I’m still receiving null values at output:

    [{"name":"1.1 PREVIOS AL INICIO ","desc":null,"values":null},{"name":"F04-PGA-S10","desc":"Acta preconstrucción","values":null},{"name":"F37-PGA-S10","desc":"Plan de inversión del anticipo","values":null},{"name":"F09-PGA-S10","desc":"Acta de vecindad","values":null},{"name":"F05-PGA-S10","desc":"Acta de inicio","values":null},{"name":"F01-PGA-S10","desc":"Desembolso de anticipo","values":null}]

Am I missing something or doing something wrong?

Answer 1

As stated by Brad Christie, MVC4 stills uses JavaScriptSerializer, so in order to get your object serialized by Json.Net, you will have to perform several steps.

First, inherit a new class JsonNetResult from JsonResult as follows (based on this solution):

public class JsonNetResult : JsonResult
{
    public JsonNetResult()
    {
        this.ContentType = "application/json";
    }

    public JsonNetResult(object data, string contentType, Encoding contentEncoding, JsonRequestBehavior jsonRequestBehavior)
    {
        this.ContentEncoding = contentEncoding;
        this.ContentType = !string.IsNullOrWhiteSpace(contentType) ? contentType : "application/json";
        this.Data = data;
        this.JsonRequestBehavior = jsonRequestBehavior;
    }

    public override void ExecuteResult(ControllerContext context)
    {
        if (context == null)
            throw new ArgumentNullException("context");

        var response = context.HttpContext.Response;

        response.ContentType = !String.IsNullOrEmpty(ContentType) ? ContentType : "application/json";

        if (ContentEncoding != null)
            response.ContentEncoding = ContentEncoding;

        if (Data == null)
            return;

        // If you need special handling, you can call another form of SerializeObject below
        var serializedObject = JsonConvert.SerializeObject(Data, Formatting.None);
        response.Write(serializedObject);
    }
}

Then, in your controller, override the Json method to use the new class:

protected override JsonResult Json(object data, string contentType, Encoding contentEncoding, JsonRequestBehavior behavior)
{
    return new JsonNetResult(data, contentType, contentEncoding, behavior);
}