No parameterless constructor defined for this object for MVC Controller

Question

I have this controller as you can see :

namespace Web.Front.Controllers
{
    public class CarController : Controller
    {
        ICarService _CarService;
        public  CarController(ICarService carService)
        {
            _CarService = carService;
        }

        // GET: Car

        public ActionResult Index()
        {

            return View();
        }
    }
}

When i call index action i get this error :

 No parameterless constructor defined for this object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.MissingMethodException: No parameterless constructor defined for this object.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[MissingMethodException: No parameterless constructor defined for this object.]
   System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +119
   System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +232
   System.Activator.CreateInstance(Type type, Boolean nonPublic) +83
   System.Activator.CreateInstance(Type type) +11
   System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +55

[InvalidOperationException: An error occurred when trying to create a controller of type 'Web.Front.Controllers.CarController'. Make sure that the controller has a parameterless public constructor.]
   System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +178
   System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +80
   System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +102
   System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +184
   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +50
   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +48
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +16
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +103
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +48
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +159

As a note i am using ninject to inject services to controllers .when i remove the service from constructor it works .

The ninject code:

  private static void RegisterServices(IKernel kernel)
    {
        kernel.Bind<DidbaanContext>().To<DidbaanContext>();
        kernel.Bind<ICarService>().To<CarService>();
        kernel.Bind<ICarRepository>().To<CarRepository>();

    }     

Answer 1

mvc needs parameterless contructions. If you have no constructor, .Net-runtime create parameterless contruction automaticly, otherwise if you have a contruction with parameter, than the runtime don't do that and raise an error.

Ether you create a new carService on each controler, or you use a serviceProvider. The unittest are simple with a serviceprovider. With asp.net core its easy enter link description here, if you use mvc 4 or 5. you can see here a see here a sample enter link description here