asp.net-mvc - 行动方法不明确

Question

我有一个网页 www.example.com，它指向 HomeController 索引。当我运行该网站时，我得到了 HomeView。

现在的要求是，当我输入 www.example.com/Japan 时，我需要运行不同的 View 。

我做了什么:

 public ActionResult Index(string country)
    {
        ViewBag.Message = "my country=" + country;

        return View();
    }

但它给了我一个错误:

The current request for action 'Index' on controller type 'HomeController' is ambiguous between the following action methods:

System.Web.Mvc.ActionResult Index() on type MvcApplication_2.Controllers.HomeController System.Web.Mvc.ActionResult Index(System.String) on type MvcApplication_2.Controllers.HomeController

我应该做什么来实现这一目标？

我不想使用http://example.com/country/japan .

我想使用http://example.com/japan .

我的代码:RouteConfig.cs

 namespace MvcApplication_2
 {
public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

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

        routes.MapRoute(
        name: "ByCountry",
        url: "{country}",
        defaults: new { controller = "Home", action = "IndexByCountry" }
    );


    }
}

}

Homecontroller.cs

 public class HomeController : Controller
 {
    [HttpGet]
    public ActionResult Index()
    {
        ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application.";

        return View();
    }


    [ActionName("IndexByCountry")]
    public ActionResult Index(string country)
    {
        ViewBag.Message = "Japan man.";

        return View("Index");
    }

    public ActionResult About()
    {
        ViewBag.Message = "Your app description page.";

        return View();
    }

    public ActionResult Contact()
    {
        ViewBag.Message = "Your contact page.";

        return View();
    }
}

Answer 1

同一个操作名称不能使用相同的 HTTP 谓词。换句话说，对于相同的操作名称使用 HttpGet 是不可能的，即使是重载也是不可能的。

您有三个选择:

将一个或您的操作方法更改为不同的 HTTP 操作动词...

[HttpGet]
public ActionResult Index()
{
    //..
}

[HttpPost]
public ActionResult Index(string country)
{
    //..
}

或者，更改操作方法的名称...

public ActionResult CountryIndex(string country)
{
    ViewBag.Message = "my country=" + country;

    return View();
}

或者，您可以从重载方法更改操作名称...

public ActionResult Index()
{
    //..
}

[ActionName("IndexByCountryName")]
public ActionResult Index(string country)
{
    //..
}

工作示例

这使用最后一个选项，保持方法名称重载，但为重载指定 ActionNameAttribute

操作

    public ActionResult Index()
    {
        ViewBag.Message = "no country selected!";

        return View();
    }

    [ActionName("IndexByCountry")]
    public ActionResult Index(string country)
    {
        ViewBag.Message = string.Format("County selected :: {0}", country);

        // the below ActionResult reuses the Index view but 
        // here you could have a separate view for the country 
        // selection if you like
        //
        return View("Index");
    }

路线

        routes.MapRoute(
            name: "ByCountry",
            url: "{country}",
            defaults: new { controller = "Home", action = "IndexByCountry" }
        );

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