RenderPartialView

        /// <summary>
        /// Renders a partial view
        /// </summary>
        StringBuilder RenderPartialView(string viewName,object model) {

            PartialViewResult partialResult = this.PartialView(viewName,model);

            ViewEngineResult engineResult = partialResult.ViewEngineCollection.FindPartialView(ControllerContext,viewName);

            if(engineResult == null)
                throw new ArgumentOutOfRangeException("FindPartialView() returned null - " + viewName);
            if(engineResult.View == null)
                throw new ArgumentOutOfRangeException("FindPartialView.View is null - " + viewName);

            IView view = engineResult.View;

            using(StringWriter writer = new StringWriter()) {
                using(HtmlTextWriter htmlWriter = new HtmlTextWriter(writer)) {

                    ViewContext vcontext = new ViewContext(
                        this.ControllerContext,
                        view,
                        this.ViewData,this.TempData,htmlWriter);

                    view.Render(vcontext,htmlWriter);
                    htmlWriter.Flush();
                    return writer.GetStringBuilder();
                }
            }
        }