ASP.NET MVC render partial view to a string to return with JSON

Question

So i have a finished method that works and i use it all over the website:

public PartialViewResult GetBlogEntries(int itemsToTake = 5)
{
    ...
    return PartialView("_BlogPost", model);
}

Now i want to get this from my javascript in JSON form.

public JsonResult GetBlogPostJson()
{      
    var blogEntry = GetBlogEntries(1);
    var lastEntryId = GetLastBlogEntryId();
    return Json(new {Html = blogEntry, LastEntryId = lastEntryId}, JsonRequestBehavior.AllowGet);
}

Idea is to get it like this:

$.ajax({
            url: '/Blog/GetBlogPostJson',
            dataType: 'json',
            success: function (data) {
                var lastEntryId = data.LastEntryId;
                var html = data.Html;
                ...
            }
        });

Problem is that this of course do not produce a string, but a PartialViewResult.

Question is, how can i resolve the PartialViewResult into html that i can send back with JSON ?

Please correct me if I wrong, you want to generate HTML, then get an Id from this HTML, and at last send both Id and HTML in JSON? — Dima, Mar 23 '13 at 15:30
Yes and no. The method GetBlogEntries() creates a partial view that i call from various places on the webpage. It does however not print out the ID anywhere. So i need to get it separately. Then send the html and the id to the caller. The javascript on the client will just make sure to only get new blog entries if there are any new ones to get. — Patrick, Mar 23 '13 at 15:39

score 16 · Accepted Answer · answered Mar 23 '13 at 15:30

16

I went through this about 6 months ago. Goal was to use a partial to populate a jquery popup dialog.

The problem is the View Engine wants to Render them in it's own awkward order...

Try this. LMK if it needs clarification.

    public static string RenderPartialViewToString(Controller thisController, string viewName, object model)
    {
        // assign the model of the controller from which this method was called to the instance of the passed controller (a new instance, by the way)
        thisController.ViewData.Model = model;

        // initialize a string builder
        using (StringWriter sw = new StringWriter())
        {
            // find and load the view or partial view, pass it through the controller factory
            ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(thisController.ControllerContext, viewName);
            ViewContext viewContext = new ViewContext(thisController.ControllerContext, viewResult.View, thisController.ViewData, thisController.TempData, sw);

            // render it
            viewResult.View.Render(viewContext, sw);

            //return the razorized view/partial-view as a string
            return sw.ToString();
        }
    }

answered Mar 23 '13 at 15:30

Dave Alperovich

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how do i pass (Controller thisController), can you show me how i would use your method? – WingMan20-10 Sep 03 '13 at 19:54
This works but it is not unit testable. :( – Dan Hunex Jul 21 '14 at 20:44
@DanHunex, RenderPartialViewToString is not easy to unit test. But if you unit test your Controllers, this is a one-off step. – Dave Alperovich Jul 21 '14 at 21:44
@DaveA Yeah I test my controller . I want to test my 'GetBlogPostJson' – Dan Hunex Jul 21 '14 at 21:45
@DanHunex you should be able to unit test the method. I struggle to come up with a worthwhile success condition though. Confirming that a non-null string is returned seems limited. – Dave Alperovich Jul 21 '14 at 21:54
How are you using this method?? – Sandeep Nov 14 '14 at 16:02
1

@Sandeep, pass the calling controller, viewname in string, and passing model. The method will run the View Factory from your Controller to produce and HTML string – Dave Alperovich Nov 14 '14 at 18:09

ASP.NET MVC render partial view to a string to return with JSON

1 Answers1