public static void Register(HttpConfiguration config) { // Web API routes config.MapHttpAttributeRoutes(); config.Routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); var json = config.Formatters.OfType <JsonMediaTypeFormatter>().First(); //json.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver(); json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects; config.Formatters.Remove(config.Formatters.XmlFormatter); json.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore; config.Formatters.Add(json); config.DependencyResolver = AutofacConfiguration.ConfigureAutofac(); }