Question

I can create a class dynamically, and then instantiate it and call a method within it from the immediate window in Visual Studio. But I cannot make a MVC Controller class behave like expected (i.e. be found and routed to). What am I missing?

Global.asax.cs:

    protected void Application_Start()
    {
        RoslynExperiments.AddController();
        RegisterRoutes(RouteTable.Routes);

…

RoslynExperiments:

    public static void AddController()
    {

        var controllerCode = @"using System.Web.Mvc;

    public class FooController:Controller
    {
        public ActionResult Index()
        {
            return Content(""foo"");
        }
    }
";

        AddDynamicAssemblyClass("FooController", controllerCode);

    }


    public static void AddDynamicAssemblyClass(string inMemoryAssemblyName, string code)
    {
        var syntaxTree = SyntaxTree.ParseText(code);

        var refs = new[] {
            MetadataReference.CreateAssemblyReference("mscorlib"),
            MetadataReference.CreateAssemblyReference("System"),
            MetadataReference.CreateAssemblyReference("System.Web"),
            MetadataReference.CreateAssemblyReference("System.Web.MVC")
        };

        var compilation = Compilation.Create(inMemoryAssemblyName,
        syntaxTrees: new[] { syntaxTree },
        references: refs,
        options: new CompilationOptions(OutputKind.DynamicallyLinkedLibrary));

        using (var memoryStream = new MemoryStream())
        {
            EmitResult result = compilation.Emit(memoryStream);
            memoryStream.Flush();
            var assembly = Assembly.Load(memoryStream.GetBuffer());
        }

    }

Answer 1

I don’t have much experience with ASP.NET MVC rounting, but according to one comment, only controllers from referenced assemblies are considered, not from all loaded assemblies.

Because of that, I think you need to use a custom ControllerFactory.