The parameters dictionary contains a null entry for parameter 'idd' of non-nullable type 'System.Int32'

Question

I am new here to learn MVC. I struck on this error, I couldn't find the solution.

My Controller Look like this:

public class EmployeeDataController : Controller
{
    public ActionResult Details(int idd)
    {
        EmployeeDataContext edc = new EmployeeDataContext();
        EmployeeData employee=  edc.employeedata.Single(emp => emp.id == idd);

        return View(employee);
    }
}

When executing the Details method from the browser (i.e. http://localhost:4166/EmployeeData/details/1) I get this error:

The parameters dictionary contains a null entry for parameter 'idd' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Details(Int32)' in 'MvcDemo1.Controllers.EmployeeDataController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters

Any help would be great to solve my problem.

---

When i update my code and try to compile the program, there is no error at compile time but when i run the program that time i got an error

EmployeeData employee=  edc.employeedata.Single(x=>x.id==id);

**An exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.SqlServer.dll but was not handled in user code

Additional information: An error occurred while executing the command Definition **

Answer 1

When you visit a URL such as EmployeeData/details/1, MVC will use your routes to map the controller, action method and parameters to use. By default the route you will have will look something like this:

routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

With your URL, this says to take the EmployeeData as the controller, details as the action method and 1 as the value for the optional parameter with the name id. Your parameter is called idd so it's not mapped. As the parameter is marked as optional but it's non-nullable in your Details method an exception occurs.

You have three ways of solving this.

Firstly, you could change your route to use idd instead of id:

routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{idd}",
    defaults: new { controller = "Home", action = "Index", idd = UrlParameter.Optional }
);

Secondly, you could change the parameter in your Details method to be called id:

public ActionResult Details(int id)...

Finally, you could change the URL you are using to be explicit in the parmater being sent:

localhost:4166/EmployeeData/details?idd=1

Answer 2

If you are using default route config - than simply rename your action parameter to id:

 public ActionResult Details(int id)
 {
     EmployeeDataContext edc = new EmployeeDataContext();
     EmployeeData employee = edc.employeedata.Single(emp=>emp.id == id);

     return View(employee);
 }

Your parameter name id should exactly match one in the route config.