MVC service that returns JSON for use with GET (JQuery ajax). Doesn't work

Question

I have a WCF web service (.svc) like this:

Web Service

Interface

namespace Interfaces
{
    [ServiceContract]
    public interface IGeneral
    {
    [OperationContract]
    [WebInvoke(Method = "GET", BodyStyle = WebMessageBodyStyle.WrappedRequest,
                         ResponseFormat = WebMessageFormat.Json)]
    List<Person> GetPerson(long personID, DateTime startDate);
    }
}

Class

[ScriptService]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class GeneralService : Interfaces.IGeneral
{
    [ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = true)]
    [WebMethod]
    public List<Person> GetPerson(long personID, DateTime startDate)
    {
        List<Person> people= new List<Person>();
        people.Add(new Person()
        {
            PersonID= 2,
            StartDate= new DateTime(),
        });
        return people;
    }
}

Person

namespace Models
{
    [DataContract]
    public class Person
    {
        [DataMember]
        public long PersonID{ get; set; }
        [DataMember]
        public DateTime StartDate{ get; set; }

    }
}

I'm expecting this to come back with Json but it just gives an error. I should be able to test this from the browser being a GET just like this (as you can see I donøt use the parameters in input so there should be no problem not passing them in):

http://localhost:2880/GeneralService/GetPerson

the way I call it is this:

Client Call

var request = {
    personID: 3,
    startDate: new Date(),
 };

ajaxService = (function () {
    var ajaxGetJson = function (method, request, callback, service) {
        $.ajax({
            url: getSvcUrl(service, method),
            type: "GET",
            data: request,
            dataType: "json",
            contentType: "application/json; charset=utf-8",
            success: function (result, statusMsg, status)
            {
                callback(result, statusMsg, status, request)
            },
            error: ServiceFailed // When Service call fails
        })
    }
    return {
        ajaxGetJson: ajaxGetJson,
    };
})();

ajaxService.ajaxGetJson("GetPerson", request, ModelMetricsMapper, "http://localhost:2880/GeneralService/");

UPDATE

I have a bit more info, it seems that it works if I change the class that I'm returning. I explain: if my class is just a simple class with primitives inside it does NOT work, BUT if I add a wrapper class around each primitive... it suddenly works. It seems that the response Class needs to be 2 levels nested at least.

Here is the new class that works:

Works

[DataContract] 
public class Person { 
    [DataMember] 
    public IdClass PersonID{ get; set; } 
    [DataMember] 
    public DateClass StartDate{ get; set; } 
}

WHY?

I will answer this question with a way I found that works using javascriptSerializer.Serialize and retuning a Strem back to the client, but I would really like a way to do it returng a Person Object like Dave Ward says in this post: http://encosia.com/asp-net-web-services-mistake-manual-json-serialization/ but I just canøt make it work.

What am I doing wrong?

Thanks for any help.

As I sayd I can overcome this problem doing a manual serialization as said in this post: http://stackoverflow.com/questions/3078397/returning-raw-json-string-in-wcf but please find me another way — Maurizio In denmark, May 30 '13 at 09:53
I have a bit more info, it seems that it works if I change the class that I'm returning, I explain: if my class is just a simple class with primitives inside it does NOT work, BUT if I add a wrapper class around each primitive... it suddenly works. Here is the new class that works: [DataContract] public class Person { [DataMember] public IdClass PersonID{ get; set; } [DataMember] public DateClass StartDate{ get; set; } } WHY? — Maurizio In denmark, May 31 '13 at 09:33

score 0 · Answer 1 · answered May 31 '13 at 13:04

0

It looks like adding the wrapper forces your data to come back as key value pairs rather than just values. Key value pairs are the format that JSON needs in order to read it properly.

answered May 31 '13 at 13:04

Robyn Paxton

800
1
6
21

score 0 · Accepted Answer · edited Aug 05 '14 at 08:07

I finally found what the problem was.

There were 2 DateTime fields on the response from the webservice that were not set. They were therefore trying to retunr their MinValue. But how I learned from this post: http://benpowell.org/wcf-json-serialization-error-with-datetime-minval-and-utc/ that is not working. so I just set the DateTime fields to Nullable and now everything works perfectly.

This is a WCF service returning Json using the GET method.

Hope this will help someone else.