.net core 在.Net 5中找不到IActionSelectorDecisionTreeProvider命名空间

我想创建@Html.Action的扩展方法，但IActionSelectorDecisionTreeProvider显示错误，无法加载命名空间

  var actionSelector = GetServiceOrFail<IActionSelectorDecisionTreeProvider>(currentHttpContext);

---

但是运气不好。

在Dot Net 5中运行代码

public static class HtmlHelperViewExtensions
{

    public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, object parameters = null)
    {
        var controller = (string)helper.ViewContext.RouteData.Values["controller"];

        return RenderAction(helper, action, controller, parameters);
    }

    public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, object parameters = null)
    {
        var area = (string)helper.ViewContext.RouteData.Values["area"];

        return RenderAction(helper, action, controller, area, parameters);
    }

    public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
    {
        if (action == null)
            throw new ArgumentNullException("action");

        if (controller == null)
            throw new ArgumentNullException("controller");

        //if (area == null)
        //    throw new ArgumentNullException("area");

        var task = RenderActionAsync(helper, action, controller, area, parameters);

        return task.Result;
    }

    private static async Task<IHtmlContent> RenderActionAsync(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
    {
        // fetching required services for invocation
        var currentHttpContext = helper.ViewContext?.HttpContext;
        var httpContextFactory = GetServiceOrFail<IHttpContextFactory>(currentHttpContext);
        var actionInvokerFactory = GetServiceOrFail<IActionInvokerFactory>(currentHttpContext);
        var actionSelector = GetServiceOrFail<IActionDescriptorCollectionProvider>(currentHttpContext);

        // creating new action invocation context
        var routeData = new RouteData();
        var routeParams = new RouteValueDictionary(parameters ?? new { });
        var routeValues = new RouteValueDictionary(new { area = area, controller = controller, action = action });
        var newHttpContext = httpContextFactory.Create(currentHttpContext.Features);

        newHttpContext.Response.Body = new MemoryStream();

        foreach (var router in helper.ViewContext.RouteData.Routers)
            routeData.PushState(router, null, null);

        routeData.PushState(null, routeValues, null);
        routeData.PushState(null, routeParams, null);

        var actionDescriptor = actionSelector.ActionDescriptors.Items.Where(i => i.RouteValues["controller"] == controller && i.RouteValues["action"] == action).First();
        var actionContext = new ActionContext(newHttpContext, routeData, actionDescriptor);

        // invoke action and retreive the response body
        var invoker = actionInvokerFactory.CreateInvoker(actionContext);
        string content = null;

        await invoker.InvokeAsync().ContinueWith(task => {
            if (task.IsFaulted)
            {
                content = task.Exception.Message;
            }
            else if (task.IsCompleted)
            {
                newHttpContext.Response.Body.Position = 0;
                using (var reader = new StreamReader(newHttpContext.Response.Body))
                    content = reader.ReadToEnd();
            }
        });

        return new HtmlString(content);
    }

    private static TService GetServiceOrFail<TService>(HttpContext httpContext)
    {
        if (httpContext == null)
            throw new ArgumentNullException(nameof(httpContext));

        var service = httpContext.RequestServices.GetService(typeof(TService));

        if (service == null)
            throw new InvalidOperationException($"Could not locate service: {nameof(TService)}");

        return (TService)service;
    }

公共静态类HtmlHelpViewExtensions
{
公共静态IHtmlContent RenderAction（此IHtmlHelper帮助程序，字符串操作，对象参数=null）
{
var controller=（string）helper.ViewContext.RouteData.Values[“controller”]；
返回渲染（助手、动作、控制器、参数）；
}
公共静态IHtmlContent RenderAction（此IHtmlHelper帮助程序、字符串操作、字符串控制器、对象参数=null）
{
var area=（string）helper.ViewContext.RouteData.Values[“area”]；
返回渲染（辅助对象、动作、控制器、区域、参数）；
}
公共静态IHTML内容呈现（此IHTML帮助器、字符串操作、字符串控制器、字符串区域、对象参数=null）
{
if（action==null）
抛出新的异常（“操作”）；
如果（控制器==null）
抛出新的异常（“控制器”）；
//如果（面积==null）
//抛出新的异常（“区域”）；
var task=RenderActionAsync（助手、操作、控制器、区域、参数）；
返回任务。结果；
}
专用静态异步任务RenderActionAsync（此IHtmlHelper帮助程序、字符串操作、字符串控制器、字符串区域、对象参数=null）
{
//获取调用所需的服务
var currentHttpContext=helper.ViewContext？.HttpContext；
var httpContextFactory=GetServiceOrFail（currentHttpContext）；
var actionInvokerFactory=GetServiceOrFail（currentHttpContext）；
var actionSelector=GetServiceOrFail（currentHttpContext）；
//创建新的操作调用上下文
var routeData=新routeData（）；
var routeParams=新的RouteValueDictionary（参数？？新{}）；
var routeValues=new RouteValueDictionary（new{area=area，controller=controller，action=action}）；
var newHttpContext=httpContextFactory.Create（currentHttpContext.Features）；
newHttpContext.Response.Body=newMemoryStream（）；
foreach（helper.ViewContext.RoutedData.Routers中的var路由器）
PushState（路由器，空，空）；
PushState（null，routeValue，null）；
routeData.PushState（null，routeParams，null）；
var actionDescriptor=actionSelector.ActionDescriptors.Items.Where（i=>i.RouteValues[“controller”]==controller&&i.RouteValues[“action”]==action）.First（）；
var actionContext=newactioncontext（newHttpContext、routeData、actionDescriptor）；
//调用操作并检索响应体
var invoker=actionInvokerFactory.CreateInvoker（actionContext）；
字符串内容=null；
wait invoker.InvokeAsync（）.ContinueWith（任务=>{
if（task.IsFaulted）
{
内容=task.Exception.Message；
}
else if（任务已完成）
{
newHttpContext.Response.Body.Position=0；
使用（var reader=newstreamreader（newHttpContext.Response.Body））
content=reader.ReadToEnd（）；
}
});
返回新的HtmlString（内容）；
}
专用静态TService GetServiceOrFail（HttpContext HttpContext）
{
if（httpContext==null）
抛出新ArgumentNullException（nameof（httpContext））；
var service=httpContext.RequestServices.GetService（typeof（TService））；
if（服务==null）
抛出新的InvalidOperationException（$“找不到服务：{nameof（TService）}”）；
返回（TService）服务；
}

---

}

使用Microsoft.AspNetCore.Mvc.Infrastructure；替换

//var actionSelector=GetServiceOrFail（currentHttpContext）；var actionSelector=GetServiceOrFail（currentHttpContext）它正在工作，但我们需要更新代码行，我想在其中使用
var actionDescriptor=actionSelector.ActionDescriptors.Items.where（I=>I.RouteValues[“controller”]==controller&&I.RouteValues[“action”]==action）。First（）
public static class HtmlHelperViewExtensions
{

    public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, object parameters = null)
    {
        var controller = (string)helper.ViewContext.RouteData.Values["controller"];

        return RenderAction(helper, action, controller, parameters);
    }

    public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, object parameters = null)
    {
        var area = (string)helper.ViewContext.RouteData.Values["area"];

        return RenderAction(helper, action, controller, area, parameters);
    }

    public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
    {
        if (action == null)
            throw new ArgumentNullException("action");

        if (controller == null)
            throw new ArgumentNullException("controller");

        //if (area == null)
        //    throw new ArgumentNullException("area");

        var task = RenderActionAsync(helper, action, controller, area, parameters);

        return task.Result;
    }

    private static async Task<IHtmlContent> RenderActionAsync(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
    {
        // fetching required services for invocation
        var currentHttpContext = helper.ViewContext?.HttpContext;
        var httpContextFactory = GetServiceOrFail<IHttpContextFactory>(currentHttpContext);
        var actionInvokerFactory = GetServiceOrFail<IActionInvokerFactory>(currentHttpContext);
        var actionSelector = GetServiceOrFail<IActionDescriptorCollectionProvider>(currentHttpContext);

        // creating new action invocation context
        var routeData = new RouteData();
        var routeParams = new RouteValueDictionary(parameters ?? new { });
        var routeValues = new RouteValueDictionary(new { area = area, controller = controller, action = action });
        var newHttpContext = httpContextFactory.Create(currentHttpContext.Features);

        newHttpContext.Response.Body = new MemoryStream();

        foreach (var router in helper.ViewContext.RouteData.Routers)
            routeData.PushState(router, null, null);

        routeData.PushState(null, routeValues, null);
        routeData.PushState(null, routeParams, null);

        var actionDescriptor = actionSelector.ActionDescriptors.Items.Where(i => i.RouteValues["controller"] == controller && i.RouteValues["action"] == action).First();
        var actionContext = new ActionContext(newHttpContext, routeData, actionDescriptor);

        // invoke action and retreive the response body
        var invoker = actionInvokerFactory.CreateInvoker(actionContext);
        string content = null;

        await invoker.InvokeAsync().ContinueWith(task => {
            if (task.IsFaulted)
            {
                content = task.Exception.Message;
            }
            else if (task.IsCompleted)
            {
                newHttpContext.Response.Body.Position = 0;
                using (var reader = new StreamReader(newHttpContext.Response.Body))
                    content = reader.ReadToEnd();
            }
        });

        return new HtmlString(content);
    }

    private static TService GetServiceOrFail<TService>(HttpContext httpContext)
    {
        if (httpContext == null)
            throw new ArgumentNullException(nameof(httpContext));

        var service = httpContext.RequestServices.GetService(typeof(TService));

        if (service == null)
            throw new InvalidOperationException($"Could not locate service: {nameof(TService)}");

        return (TService)service;
    }