Mvc Render Action/Partial to Response Output

Question

Although @Html.RenderPartial calls write and returns void, it is still writing to a StringWriter/StringBuilder. Is there a way to render directly to the ResponseStream?

Can this be done with a custom IViewEngine that implements render like PdfView to directly output to the ResponseStream?

ADDITION

ViewResultBase.ExecuteResult shows the ViewContext being built with Response.Output, but debugger shows ViewContext.Writer as a StringWriter

Both of these approaches results in a StringWriter

return PartialView("view", Model)
// or
PartialView("view", Model).ExecuteResult(ControllerContext)

EDIT

It appears that System.Web.WebPages.WebPageBase ExecutePageHeirarchy pushes a temp StringWriter onto the context stack, so I'm not sure if this can be bypassed

IN SUMMARY

RenderPartial, RenderAction do not directly output to the Response.Stream, none of Razor Views will

SOLUTION

It was the new WebPages/Razor rendering engine that wraps everything with a StringWriter to a StringBuilder. The solution was to change my page to use the WebFormViewEngine which does not apply this wrapping.

Instead of updating the answer with solution, It would be more convenient for users seeking similar problem if you add solution as answer. — vendettamit, Jan 04 '16 at 15:20

score 0 · Answer 1 · answered Dec 31 '15 at 11:04

This below method illustrates one way achieving the outcome you are looking for:

// <summary>
// An extension methods for rendering a model/view into a stream
// </summary>
// <param name="myModel">The model you are trying render to a stream</param>
// <param name="controllerBase">This will come from your executing action</param>
// <returns></returns>
        public static Stream GetStream(CustomModel myModel, ControllerBase controllerBase)
        {
            //we will return this stream
            MemoryStream stream = new MemoryStream();

            //you can add variables to the view data
            controllerBase.ViewData["ViewDataVariable1"] = true;

            //set your model
            controllerBase.ViewData.Model = myModel;

            //The example uses the UTF-8 encoding, you should change that if you are using some other encoding.
            //write to a stream
            using (StreamWriter writer = new StreamWriter(stream, Encoding.UTF8))
            {
                using (var sw = new StringWriter())
                {
                    //render the view  ~/Views/Shared/_FeedbackMessage.cshtml (can be passed in as a parameter if you want to make it super generic)
                    var viewResult = ViewEngines.Engines.FindPartialView(controllerBase.ControllerContext, "_FeedbackMessage");

                    //create a new view context
                    var viewContext = new ViewContext(controllerBase.ControllerContext, viewResult.View, controllerBase.ViewData, controllerBase.TempData, sw);

                    //Render the viewengine and let razor do its magic
                    viewResult.View.Render(viewContext, sw);    
                    viewResult.ViewEngine.ReleaseView(controllerBase.ControllerContext, viewResult.View);

                    //get StringBuilder from StringWriter sw and write into the stream writer
                    //you could simply return the StringWriter here if that is what you were interested in doing
                    writer.Write(sw.GetStringBuilder().ToString());

                    writer.Flush();

                    stream.Position = 0;
                }

            }

            //return the stream from the above process
            return stream;
        }

This is no different then ViewResultBase. My goal is to output directly to Response.Output and to not capture it in a StringBuilder. - The issue is not with MVC, but with the System.Web.WebPages.WebPageBase which wraps the call into a new wrapped StringWriter. - My end solution was to use to WebFormViewEngine which does allow for direct output to the response stream — Steve, Jan 04 '16 at 14:38

Mvc Render Action/Partial to Response Output

1 Answers1