Create a new Viewclass based on the WebFormView, and use that as the ViewEnging for rendering (by returning this View in the CreatePartialView and CreateView methods of a custom WebFormViewEngine).

Override the Render method in your new Viewclass and create a new TextWriter.
Store the viewContent.Writer and set the viewContent.Writer to the newly created TextWriter.
Call MyBase.Render(viewContext,writer).
The writer is ignored, but you just changed the writer of the viewContext so any output goes there and not to the Response!

Restore the viewContext.Writer.

You can now use the content of the newly created TextWriter and do anything you like.
Finally write the changed content to the old viewContent.Writer (which writes to Response).

Performance does not degrade as far as I can tell and this works for partialrendering as well as for normal pages.
Basically for all view rendered output.

Example:

Imports System.IO

Public Class CustomRenderView
Inherits WebFormView

Public Sub New(ByVal viewPath As String)
MyBase.New(viewPath)
End Sub

Public Sub New(ByVal viewPath As String, ByVal masterPath As String)
MyBase.New(viewPath, masterPath)
End Sub

Public Overrides Sub Render(ByVal viewContext As System.Web.Mvc.ViewContext, ByVal writer As System.IO.TextWriter)
Dim newWriter As TextWriter = New StringWriter()

Dim oldWriter As TextWriter = viewContext.Writer
viewContext.Writer = newWriter

MyBase.Render(viewContext, newWriter) ‘use newWriter in case MS changes its mind to ignore it…
viewContext.Writer = oldWriter

Dim pageSource As String = newWriter.ToString()
‘do something with the generated output in pageSource

‘write changed output to the original viewContext.Writer (goes to Response object)
oldWriter.Write(pageSource)
End Sub

End Class

That’s all folks!

Currently, I am casting the ViewData Objects in the partial view (not using a view model)

Unfortunately, ViewData seems to be empty when rendering.. No matter what I pass into RenderPartialToString as the viewData…

NE thoughts?

http://msug.vn.ua/blogs/bobasoft/archive/2010/01/07/render-partialview-to-string-asp-net-mvc.aspx – nicer solution


public static string RenderPartialToString(this HtmlHelper htmlHelper, string controlName, object viewData)
{
// Added Url to allow ascx to use Url.Action()
var urlHelper = new UrlHelper(htmlHelper.ViewContext.RequestContext);
// Added ViewContext to allow ascx to use Html helpers
var vp = new ViewPage { ViewData = vd, ViewContext = htmlHelper.ViewContext, Url = urlHelper};


Note this is an Html helper called with Html.RenderPartialToString(). If not, use these changes:


var vc = new ViewContext();
// Added Url to allow ascx to use Url.Action()
var urlHelper = new UrlHelper(vc.RequestContext);
// Added ViewContext to allow ascx to use Html helpers
var vp = new ViewPage { ViewData = vd, ViewContext = vc, Url = urlHelper };


Gary

The trap did not occur if the control was referenced by Html.RenderPartial() instead of RenderPartialToString().

Gary

To:

ViewPage vp = new ViewPage { ViewData = (ViewDataDictionary)viewData };


Not sure why but when I created the ViewDataDictionary object with the constructor I was losing all of viewData’s parameters.

As far as I know, your point is quite valid. If you want to render an entire view to a string, the previous post will work and this one will not.

However, the idea behind RenderPartialToString, is geared at just that, rendering a partial view to a string.

This is just rendering a partial as views don’t extend Control.

So, if you wanted to actually generate an entire view into a string, you’d still need to use the old method. That or rework your views to be partials instead…