如何保证HTTPContext有价值？

Question

我正在构建 MVC Storefront 的一个版本。我有两个主题，一个是标准 ui，另一个是管理 ui。我有一些 HTML Helper 方法，它们将 .ascx 文件传递​​到 .aspx 文件，就像示例一样，但没有插件。所有的东西都适用于默认主题，但它们都不适用于管理主题。当 Html.SimpleActivityTypeList() 触发时，我总是遇到相同的错误。 Html.RenderPartial(“AdminLeftNav”) 将始终工作正常。

<asp:Content ID="Content3" ContentPlaceHolderID="NavContent" runat="server">
    <% Html.SimpleActivityTypeList(); %>
    <% Html.RenderPartial("AdminLeftNav"); %>
</asp:Content>

我已将如下方法添加到扩展类中。

public static void SimpleActivityTypeList(this HtmlHelper helper)
    {
        helper.RenderAction<CatalogController>(x => x.SimpleActivityTypeList());
     }

正如我所说，这在默认主题中效果很好。 请帮忙？

Stack Trace: 


[ArgumentNullException: Value cannot be null.
Parameter name: httpContext]
   System.Web.Routing.RequestContext..ctor(HttpContextBase httpContext, RouteData routeData) +85
   Microsoft.Web.Mvc.ViewExtensions.RenderRoute(HtmlHelper helper, RouteValueDictionary values) +367
   Microsoft.Web.Mvc.ViewExtensions.RenderAction(HtmlHelper helper, Expression`1 action) +113
   GrandGuide.Web.CMSExtensions.SimpleActivityTypeList(HtmlHelper helper) in C:\S3_Depot\S3_Dev\GrandGuide\GrandGuide.Web\Infrastructure\Helpers\CMSExtensions.cs:55
   ASP.views_themes_admin_index_aspx.__RenderContent3(HtmlTextWriter __w, Control parameterContainer) in c:\S3_Depot\S3_Dev\GrandGuide\GrandGuide.Web\Views\Themes\Admin\Index.aspx:7
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +256
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
   System.Web.UI.Control.Render(HtmlTextWriter writer) +10
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   ASP.views_themes_admin_theme_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in c:\S3_Depot\S3_Dev\GrandGuide\GrandGuide.Web\Views\Themes\Admin\Theme.Master:33
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +256
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
   System.Web.UI.Control.Render(HtmlTextWriter writer) +10
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +134
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
   System.Web.UI.Page.Render(HtmlTextWriter writer) +29
   System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer) +71
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1266

Answer 1

更多信息会有帮助。过去，我使用过：

if (null != HttpContext)

或者，如果您要访问上下文中的某些内容，例如会话变量：

if (null != HttpContext.Current.Session["my_var"])