visual studio 2010 - Razor intellisense error: Feature 'extension method' cannot be used because it is not part of the ISO-2 C# language specification

Question

Goal:

• Use cshtml Razor templates to format data
• Embed cshtml Razor templates in Class Library as Embedded Resources
• Use Linq statements and extension methods in the cshtml template

I created a new class library project, then adapted Scott Hanselman's instructions on how to integrate MVC3 into a WebForms application to get it to work in a Class Library. Then I use the NuGet package RazorEngine to apply the template to an object.

So far it works great, with one hiccup: The intellisense does not recognize Linq statements or extension methods (a pretty important part of MVC) when editing cshtml files.

So for the following cshtml file:

@model Customer[]

@Model.Count()

@if (Model.Where(customer => customer.Type == 'New').Any())
{
    <span>Found at least one new customer.</span>
}

...it displays the following errors:

Feature 'extension method' cannot be used because it is not part of the ISO-2 C# language specification

Feature 'lambda expression' cannot be used because it is not part of the ISO-2 C# language specification

Does anyone know what I'm missing? Thank you in advance--I've spent hours searching for the answer to this.

---

Some additional details

The following is my web.config in the Views folder:

<?xml version="1.0"?>
<configuration>
  <configSections>
    <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
      <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
      <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
    </sectionGroup>
  </configSections>
  <system.web.webPages.razor>
    <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
    <pages pageBaseType="System.Web.Mvc.WebViewPage">
      <namespaces>
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Routing" />
      </namespaces>
    </pages>
  </system.web.webPages.razor>
  <appSettings>
    <add key="webpages:Enabled" value="false" />
  </appSettings>

  <system.web>
    <httpHandlers>
      <add path="*" verb="*" type="System.Web.HttpNotFoundHandler" />
    </httpHandlers>
    <pages validateRequest="false" pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
      <controls>
        <add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.Mvc" tagPrefix="mvc" />
      </controls>
    </pages>
  </system.web>

  <system.webServer>  ...  </system.webServer>
</configuration>

And I added a web.config file to the root of the project. It contains the following:

<configuration>
<system.web>
  <compilation debug="true" targetFramework="4.0">
    <assemblies>
      <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      <add assembly="System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      <add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      <add assembly="System.Web.WebPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
    </assemblies>
  </compilation>
  ...
  <pages>
    <namespaces>
      <add namespace="System.Web.Helpers" />
      <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.WebPages" />
    </namespaces>
  </pages>
</system.web>
...
</configuration>

And here are the references for the project:

The Class Library has a target framework of .NET Framework 4 and under Advanced Build Settings, the Language Version is set to C# 3.0.

Update

The project builds and runs properly when using extension methods and Linq. It's just the intellisense that is throws the error.

Answer 1

The key of solving this issue is adding the following tag to your app.config or web.config

<system.web>
    <compilation debug="false" targetFramework="4.0" />
</system.web>

Note: In some cases, unloading and reloading the project is required.