c# - 自定义枚举作为可选参数

Question

  public enum Employee
    {
        FT,
        PT,
    }

这行不通

  public ActionResult Index(Employee s = Employee.PT)
        {
            ViewData["Message"] = s.ToString();

            return View("MyView");
        }

Exception Details: System.ArgumentException: The parameters dictionary contains an invalid entry for parameter 's' for method 'System.Web.Mvc.ActionResult Index(SampleControllerEx.Controllers.Employee)' in 'SampleControllerEx.Controllers.HomeController'. The dictionary contains a value of type 'System.Int32', but the parameter requires a value of type 'SampleControllerEx.Controllers.Employee'. Parameter name: parameters

但下面一个是可行的，

public ActionResult Index([DefaultValue(Employee.PT)] Employee s)
        {
            ViewData["Message"] = s.ToString();

            return View("MyView");
        }

我可以知道为什么 'DefaultValue' 只支持自定义枚举，而可选参数 (4.0) 不支持吗？

Answer 1

你可以这样做:

 public ActionResult Index(int employeeType)
        {
            Employee s = (Employee) employeeType;
            ViewData["Message"] = s.ToString();

            return View("MyView");
        }