Calling .net web service with complex parameters

Question

I have seen many examples of json web services with WCF in asp.net that accept one in-parameter. I need my service method to accept many parameters and return a list like this;

This is my Service.svc:

public class Car
{
    public string Title;
    public int Number;
}

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]

public class Service
{

    [OperationContract]
    [WebInvoke(Method = "POST", ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json)]
    public List<Car> GetCarById(int userid, string password , List<Cars> carlist)
    {
        //Doing some stuff here
    }
}

In my web.config:

<system.serviceModel>
   <behaviors>
       <endpointBehaviors>
             <behavior name="ServiceAspNetAjaxBehavior">
                 <enableWebScript />
             </behavior>
       </endpointBehaviors>
    </behaviors>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
   <services>
         <service name="Service">
             <endpoint address="" behaviorConfiguration="ServiceAspNetAjaxBehavior"
 binding="webHttpBinding" contract="Service" />
          </service>
  </services>
  </system.serviceModel>

How can I call this service if I want to pass all these parameters? When I try to call the method with the params userid, password and carlist, they are all null. This is what I send to http://localhost/Service.svc/GetCarById using POST in an application called Fiddler:

HEADERS:
Host: localhost
Content-Length: 136
Content-Type: application/json; charset=utf-8

BODY:
{"d":{"password":"test","userid":123,"carlist":[{"__type":"Car","Number":1,"Title":"BMW"},{"__type":"Car","Number":2,"Title":"Honda"}]}}

The response is: {"d":null} The method is returning carlist, so I know the method is called and that carlist is null. If I change the method to return a string for example "Error" I get that back, so I know the method is called..

Do you have an idea what I'm doing wrong?

Answer 1

Can you change the signature of your method. If so, why not create a Request object that encapsulates your parameters? Like this:

public class GetCarByIdRequest
{
   public int CarId {get;set;}
   public int Password {get;set;}
   public List<Car> CarList {get;set;}
}

Answer 2

See original question...

Answer 3

Finally found the solution:

Changed from:

[WebInvoke(Method = "POST", ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json)]

To just:

[WebInvoke]

And then I called the service without the initial "d", everything works perfect!

Thanks for your help!