Razor heper方法无法识别

Question

Ever since I upgraded my project to MVC4, my Razor helpers are marked with red squiggles, and intellisense doesn't work; everything works at design time though. Can anyone help?

Here is what my Views/Web.config has.

<system.web.webPages.razor>
  <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
  <pages pageBaseType="Qwiple.Web.Views.BaseViewPage">
    <namespaces>
      <add namespace="System.Web.Mvc" />
      <add namespace="System.Web.Mvc.Ajax" />
      <add namespace="System.Web.Mvc.Html" />
      <add namespace="System.Web.Routing" />
      <add namespace="System.Web.Helpers"/>
    </namespaces>
  </pages>
</system.web.webPages.razor>

Answer 1

In my case, the following line was missing from the razor section in the Views/web.config, under namespaces:

<add namespace="System.Web.Helpers"/>

Note that this line is present in Joe's original example above, so we're not all having the same problem.

Answer 2

I figured it out. During the upgrade I missed changing the version of the razor section in the Views/web.config. Make sure that the section groups match the sample below.

<sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
  <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
  <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
</sectionGroup>