Posting to WCF json endpoint with angular

Question

I am trying to post to a WCF json service endpoint from angular but have been unsuccessful in my attempts. I have verified the service is working by other means and working for the specified URL.

Using firebug I can see the request being output as such:

NetworkError: 400 Bad Request - http://www.myapi.com/V1/Service.svc/Authenticate?Password=password&UserName=username"

angular code

app.service('UserService', function ($http) {
this.GetLoginStatus = function (AuthenticateRequest) {
    $http({
        url: APIURL + "/Authenticate",
        method: "POST",
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded'
        },
        params: AuthenticateRequest,
        data: {
            'Code': 'test data'
        }
    });
};

});

WCF Iservice

[WebInvoke(RequestFormat = WebMessageFormat.Json,
ResponseFormat = WebMessageFormat.Json,
Method = "POST",
BodyStyle = WebMessageBodyStyle.Wrapped)]
[OperationContract]
AuthenticateResponse Authenticate(AuthenticateRequest Request);

Request definition

[DataContract]
public class AuthenticateRequest
{
    [DataMember]
    public String UserName { get; set; }
    [DataMember]
    public String Password { get; set; }
}

Answer 1

I managed to get this done by stringfy-ing a javascript object.

    Service.js

        angular.module('myModule').factory('serviceFac', ['$http', '$q', 
function (a, b) 
    {   var taskMergeServiceNameSet = "WebServuice.svc/Tasks/SetTasks";
            return {
                setTasksMerge: function (taskIds, action) {

                 var objArray = '';
                 var obj = {
                        taskIds: taskIds,
                        action: action,
                        userName: "ss"
                  };
                 objArray = new Array();
                 objArray.push(obj);
                 var deferred = b.defer();
                 a({
                   url: taskMergeServiceNameSet,
                   method: 'POST',
                   headers: { 'Content-Type':'application/json; charset=utf-8'},
                   data: JSON.stringify(objArray)
                  }
                  ).sucess(function (data) { deferred.resolve(data) })
                  .error(function (msg, code) { deferred.reject(msg) });    
                    return deferred.promise;
                }
            }
        }]);

Service Contract

ServiceContract Interface

[ServiceContract]
public interface ITasks
{
   [OperationContract]
    [WebInvoke(Method = "POST",RequestFormat=WebMessageFormat.Json ,
      ResponseFormat =   WebMessageFormat.Json, 
      UriTemplate = "Tasks/SetTasksForMerge")]
    string CreateNewTaks(valObj[] values);        
}

[DataContract]
public class valObj
    {
    [DataMember]
    public string taskIds { get; set; }
    [DataMember]
    public string action { get; set; }
    [DataMember]
    public string userName { get; set; }
    }

post here helped me a lot. please let me know if you suceed in passing a JSON string