asp.net mvc - Getting a Partial View's HTML from inside of the controller

Question

I have developed a simple mechanism for my mvc website to pull in html via jquery which then populates a specified div. All is well and it looks cool.
My problem is that i'm now creating html markup inside of my controller (Which is very easy to do in VB.net btw) I'd rather not mix up the sepparation of concerns.

Is it possible to use a custom 'MVC View User Control' to suit this need? Can I create an instance of a control, pass in the model data and render to html? It would then be a simple matter of rendering and passing back to the calling browser.

Answer 1

This is a solution that is working with ASP.Net MVC 1.0 (many that claim to work with beta 3 don't work with 1.0), doesn't suffer of the 'Server cannot set content type after HTTP headers have been sent' problem and can be called from within a controller (not only a view):

/// <summary>
/// Render a view into a string. It's a hack, it may fail badly.
/// </summary>
/// <param name="name">Name of the view, that is, its path.</param>
/// <param name="data">Data to pass to the view, a model or something like that.</param>
/// <returns>A string with the (HTML of) view.</returns>
public static string RenderPartialToString(string controlName, object viewData) {
    ViewPage viewPage = new ViewPage() { ViewContext = new ViewContext() };
    viewPage.Url = GetBogusUrlHelper();

    viewPage.ViewData = new ViewDataDictionary(viewData);
    viewPage.Controls.Add(viewPage.LoadControl(controlName));

    StringBuilder sb = new StringBuilder();
    using (StringWriter sw = new StringWriter(sb)) {
        using (HtmlTextWriter tw = new HtmlTextWriter(sw)) {
            viewPage.RenderControl(tw);
        }
    }

    return sb.ToString();
}

public static UrlHelper GetBogusUrlHelper() {
  var httpContext = HttpContext.Current;

  if (httpContext == null) {
    var request = new HttpRequest("/", Config.Url.ToString(), "");
    var response = new HttpResponse(new StringWriter());
    httpContext = new HttpContext(request, response);
  }

  var httpContextBase = new HttpContextWrapper(httpContext);
  var routeData = new RouteData();
  var requestContext = new RequestContext(httpContextBase, routeData);

  return new UrlHelper(requestContext);
}

It's a static method you can drop somewhere you find it convenient. You can call it this way:

string view = RenderPartialToString("~/Views/Controller/AView.ascx", someModelObject);