C# asp.net mvc路由中的翻转路由值

我是asp.NETMVC新手，请耐心等待

我们有以下路由字典设置

routes.MapRoute(
            "Default",                                              // Route name
            "{language}/{controller}/{action}/{id}",                           // URL with parameters
            new { language = "en", controller = "Home", action = "Index", id = "" }  // Parameter defaults
        );

对于我们应用程序中的任何给定页面，我们都需要提供指向同一页面的法语版本的链接。例如，页面：

http://www.example.com/en/home

应该在该页面上有指向

http://www.example.com/fr/home

现在我有了以下UrlHelper扩展方法

public static string FilpLanguage(this UrlHelper urlHelper)
    {
        var data = urlHelper.RequestContext.RouteData;
        if (System.Threading.Thread.CurrentThread.CurrentCulture == CultureInfo.GetCultureInfoByIetfLanguageTag("en-CA"))
            data.Values["language"] = "fr";
        else
            data.Values["language"] = "en";

        return urlHelper.RouteUrl(data.Values.Where(item => item.Value != null));
    }

但是，在www.example.com/en/home上调用FilpLanguage将返回以下URL：

www.example.com/en/home?current=[,]

我是不是遗漏了什么？当前参数来自哪里

提前谢谢

更新

我发现我可以在当前请求上下文中简单地使用RouteValueDictionary

public static MvcHtmlString GetOtherLanguageLink(this HtmlHelper html, string linkText)
    {
        var routeDictionary = html.ViewContext.RouteData.Values;

        if (null == routeDictionary["action"] || !(routeDictionary["action"] is string) ||
            null == routeDictionary["controller"] || !(routeDictionary["controller"] is string))
            throw new ArgumentException("Either action or controller is missing in routeData.Values (RouteValueDictionary)");

        if (System.Threading.Thread.CurrentThread.CurrentCulture == CultureInfo.GetCultureInfoByIetfLanguageTag("en-CA"))
            routeDictionary["language"] = "fr";
        else
            routeDictionary["language"] = "en";

        // add query strings as extra route values
        foreach (string key in html.ViewContext.RequestContext.HttpContext.Request.QueryString.AllKeys)
            if (!string.IsNullOrEmpty(key) && !routeDictionary.ContainsKey(key))
                routeDictionary.Add(key, html.ViewContext.RequestContext.HttpContext.Request.QueryString[key]);

        return html.ActionLink(linkText, routeDictionary["action"].ToString(), routeDictionary["controller"].ToString(), routeDictionary, null);
    }

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