Reference problems when using VirtualPathProvider to dynamically load a view

Question

I have the following set of classes that I used to dynamically load in a View. The code below works well when called with .RenderPartial.

public class VirtFile:VirtualFile
{
    public VirtFile(string virtualPath) : base(virtualPath)
    {
    }

    public override Stream Open()
    {

        string path = this.VirtualPath;
        Stream str = new MemoryStream();
        StreamWriter writer = new StreamWriter(str);
        writer.Write(@"<%@ Control Language=""C#"" Inherits=""System.Web.Mvc.ViewUserControl"" %>
            <%="Test"%> 

            ");
        writer.Flush();
        str.Position = 0;
        return str;
    }
}
public class Provider:VirtualPathProvider
{
    public override System.Web.Caching.CacheDependency GetCacheDependency(string virtualPath, System.Collections.IEnumerable virtualPathDependencies, DateTime utcStart)
    {
        return null;
        var dependency = new System.Web.Caching.CacheDependency(virtualPath);
        return dependency;// base.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart);
    }
    public override bool DirectoryExists(string virtualDir)
    {
        if (IsVirtual(virtualDir))
        {
            return true;
        }
        return base.DirectoryExists(virtualDir);
    }
    public override bool FileExists(string virtualPath)
    {
        if (IsVirtual(virtualPath))
        {
            return true;
        }
        return base.FileExists(virtualPath);
    }
    public override VirtualFile GetFile(string virtualPath)
    {

        if(IsVirtual(virtualPath))
        {
            return new VirtFile(virtualPath);                
        }

        return base.GetFile(virtualPath);
    }

    private bool IsVirtual(string virtualPath)
    {
        return virtualPath.Contains("Database");
    }

But if I try to change the <%="Test"%> to <%=new Model.Category()%>, of create a typed View I get an error stating that "The type or namespace name 'Model' could not be found (are you missing a using directive or an assembly reference?)". However, the same code works if it is simply placed in an .ascx file.

Am I missing something, it seems like wether the stream comes from the file system or a custom VirtualPathProvider it should have the same loaded assemblies, since <%=AppDomain.CurrentDomain.ApplicationIdentity%> returns the same value from either the file system or the custom provider.

Answer 1

How your Model class look like? Is it wrapped within some namespace? VPP is pretty amazing thing and can do a lot of magic, just make sure when you passing 'string' with your virtual asp.net 'page' content you provide full path to you classes, it's safer this way. or, another option, use your web.config to link your namespaces, so app will find your classes.

Answer 2

Try adding

<%@ Import Namespace="MyApp.Model" %>

to your dynamic user control string.

EDIT:

Of course, you could also use the fully qualified name for the type, changing Model.Category() to MyApp.Model.Category(). Most of the time, I import the namespace. Just a style preference.