How to accept JSON in a WCF DataService?

[WebInvoke(Method = "POST")] public void SaveMyObj() { StreamReader r = new StreamReader(HttpContext.Current.Request.InputStream); string jsonBody = r.ReadToEnd(); // jsonBody is empty!! JavaScriptSerializer jss = new JavaScriptSerializer(); MyObj o = (MyObj)jss.Deserialize(jsonBody, typeof(MyObj)); // Now do validation, business logic, and persist my object }

System.InvalidOperationException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 'Void SaveMyObj(MyNamespace.MyObj)' has a parameter 'MyNamespace.MyObj o' of type 'MyNamespace.MyObj' which is not supported for service operations. Only primitive types are supported as parameters.

Add parameters to your method. You'll also want some additional attributes on your WebInvoke.

Here's an example (from memory so it might be a little off)

[WebInvoke(BodyStyle = WebMessageBodyStyle.Wrapped, RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json, UriTemplate = "modifyMyPerson")]
public void Modify(Person person) {
   ...
}

With person class something like this:

[DataContract]
public class Person {

[DataMember(Order = 0)]
public string FirstName { get; set; }

}

And json sent like this

var person = {FirstName: "Anthony"};
var jsonString = JSON.stringify({person: person});
// Then send this string in post using whatever, I personally use jQuery

EDIT: This is using "wrapped" approach. Without wrapped approach you would take out the BodyStyle = ... and to stringify the JSON you would just do JSON.stringify(person). I just usually use the wrapped methodology in case I ever need to add additional parameters.

EDIT For full code sample

Global.asax

using System;
using System.ServiceModel.Activation;
using System.Web;
using System.Web.Routing;

namespace MyNamespace
{
    public class Global : HttpApplication
    {
        protected void Application_Start(object sender, EventArgs e)
        {
            RouteTable.Routes.Add(new ServiceRoute("myservice", new WebServiceHostFactory(), typeof(MyService)));
        }
    }
}

Service.cs

using System;
using System.ServiceModel;
using System.ServiceModel.Activation;
using System.ServiceModel.Web;

namespace MyNamespace
{
    [ServiceContract]
    [ServiceBehavior(MaxItemsInObjectGraph = int.MaxValue)]
    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    public class MyService
    {
        [OperationContract]
        [WebInvoke(UriTemplate = "addObject", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.WrappedRequest)]
        public void AddObject(MyObject myObject)
        {
            // ...
        }

        [OperationContract]
        [WebInvoke(UriTemplate = "updateObject", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.WrappedRequest)]
        public void UpdateObject(MyObject myObject)
        {
            // ...
        }

        [OperationContract]
        [WebInvoke(UriTemplate = "deleteObject", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.WrappedRequest)]
        public void DeleteObject(Guid myObjectId)
        {
            // ...
        }
    }
}

And add this to Web.config

  <system.serviceModel>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
  </system.serviceModel>

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