Getting reference to server controls when handler is MvcHandler

Question

I am working working on an httpmodule to hide certain content on my website if certain criteria are not met. My handler setup is pretty simple. Here are the relevant parts to my question:

Public Interface IFeatureItem

  Property ID As Guid

  Sub FeatureItemPreRenderComplete(ByVal sender As Object, ByVal e As EventArgs)

End Interface

Public Class MyModule
  Implements System.Web.IHttpModule

  Public Sub Init(ByVal context As System.Web.HttpApplication) Implements System.Web.IHttpModule.Init
    AddHandler context.PreRequestHandlerExecute, AddressOf Application_PreRequestHandlerExecute
  End Sub

  Private Sub Application_PreRequestHandlerExecute(ByVal source As Object, ByVal e As EventArgs)

      If TypeOf source Is HttpApplication Then
          Dim Application As HttpApplication = source

          If TypeOf Application.Context.Handler Is Page Then
            Dim Page As Page = Application.Context.Handler
            AddHandler Page.PreRenderComplete, AddressOf FeatureItemPreRenderComplete                
          ElseIf TypeOf Application.Context.Handler Is System.Web.Mvc.MvcHandler Then
            Dim MvcHandler As System.Web.Mvc.MvcHandler = Application.Context.Handler
            <What do I do here>
        End If
      End If

  End Sub 


  Private Sub FeatureItemPreRenderComplete(ByVal source As Object, ByVal e As System.EventArgs)
    Dim Page As Page = source
    Dim Repository As IFeatureRepository = GetRepository(Page.Application)  'Holds supported IFeature
    Dim IFeatureItems As IEnumerable(Of IFeatureItem) = GetIFeatureItems(Page) 'Goes through Page's control tree and returns IFeatureItems

    For Each IFeatureItem In IFeatureItems
        Dim FeatureEventArgs As FeatureEventArgs = New FeatureEventArgs(IFeatureItem.ID, FeatureAllowed(IFeatureItem.ID, Repository))

        IFeatureItem.FeatureItemPreRenderComplete(Me, FeatureEventArgs)
    Next

  End Sub

  <Irrelevant stuff removed>

End Class

Basically setting up event handlers on the page object if the handler is a page. Then in the PreRenderEvent I loop through all the IFeatureItems on the page and call a method in IFeatureItem. This works great if the handler is a page.

This site has an mvc view for a dashboard and also contains webforms controls that could be an IFeatureItem. What I want to do is loop through the webforms controls in this view and do the same processing on them as I would on a normal page, but I can't figure out a way to do so and have had no luck googling. Is this possible within a module? Is PreRequestHandlerExecute the right event to set up my event handlers?

Answer 1

You are trying to do this from the wrong extensibility point.

In MVC the ViewPage, which inherits from Page is rendered in the virtual WebFormView method: Render(ViewContext viewContext, TextWriter writer).

Your solution is to override this Method and execute your pre-render events here.

To get a better understanding of how to do this effectively, I would suggest reviewing the source for WebFormView, ViewPage, and ViewUserControl with .NET Reflector. Basically, the WebFormView uses the BuildManager to create the ViewUserControl or ViewPage based on the ViewPath. Both of these classes derive from Control, so it should be straight forward for you from there.