Question

I’d like to use the Visual Studio 2010 MVC 3 framework for a web project that hosts VXML and CCXML rather than HTML for telephony based applications.

MVC 3 seems ideally suited to this kind of application, and I think it’s a great alternative to the more widely used jsp/Tomcat based applications that are generally used for VXML/CCXML. But there are a couple of annoyances:

1. The project tries to validate my .cshtml pages as HTML (understandably), or whatever target validation I set in Options>Text Editor>HTML>Validation>Target, but it forces me to have validation. I can’t seem to find a way to switch it off altogether. Is there a way to switch it off and prevent hundreds of warnings? or better still, write my own custom validation for CCXML/VXML?
2. Is there a way to automatically set the content-type to “text/vxml” for all views without having to write Response.ContentType = "text/vxml"; in every Action Method?

Answer 1

You could write a custom view engine based on the Razor view engine and register a custom extension for your views:

public class VXMLViewEngine : RazorViewEngine
{
    public VXMLViewEngine()
    {
        ViewLocationFormats = new[] { "~/Views/{1}/{0}.vxml", "~/Views/Shared/{0}.vxml" };
        MasterLocationFormats = new[] { "~/Views/{1}/{0}.vxml", "~/Views/Shared/{0}.vxml" };
        PartialViewLocationFormats = new[] { "~/Views/{1}/{0}.vxml", "~/Views/Shared/{0}.vxml" };
        FileExtensions = new[] { "vxml" };
    }

    protected override IView CreateView(ControllerContext controllerContext, string viewPath, string masterPath)
    {
        controllerContext.HttpContext.Response.ContentType = "text/vxml";
        return base.CreateView(controllerContext, viewPath, masterPath);
    }
}

and in Application_Start declare the custom extension:

RazorCodeLanguage.Languages.Add("vxml", new CSharpRazorCodeLanguage());
WebPageHttpHandler.RegisterExtension("vxml");
ViewEngines.Engines.Clear();
ViewEngines.Engines.Add(new VXMLViewEngine());

and the custom build provider in web.config that will recognize the .vxml extension:

<compilation debug="true" targetFramework="4.0">
  <assemblies>
      ...
  </assemblies>
  <buildProviders>
    <add extension=".vxml" type="System.Web.WebPages.Razor.RazorBuildProvider, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
  </buildProviders>
</compilation>

Now you could use .vxml as extension for the views. Since Visual Studio doesn’t recognize the .vxml extension, when you open a file with it, it won’t bother you with warnings. And you could even create a custom VS plugin that could provide syntax highlighting and Intellisense for this custom extension.