Return PartialView in JsonResult

Question

I think about migrating from .net core mvc to razor pages so I am building demo application where I try the features from mvc i used and i stucked a little when I am trying to reload some part of the page based on ajax request using partial view. Sometimes partial view is very simple, like in the following example and sometimes very complex (it can contains additional nested partial views with forms etc. and suprisingly its working well).

My CustomersModel : PageModel handler looks like

it has return JsonResult because i need feedback about errors
sometimes I return more than one partial view

public JsonResult OnGetCustomerDetailPartialView(int id)
{
    PopulateCustomers();

    var model = new PartialViews.CustomerDetailViewModel()
    {
        Customer = Customers.Where(x => x.Id == id).FirstOrDefault()
    };

    var partialView = PartialViewHelper.PartialView("/PartialViews/CustomerDetailViewModel.cs", model, ViewData, TempData);

    return new JsonResult(new { success = true, html = partialView.ToStringExtension() });
}

Partial View helper

public static class PartialViewHelper
    {
        public static PartialViewResult PartialView(string viewName, object model,
            ViewDataDictionary viewData, ITempDataDictionary tempData)
        {
            viewData.Model = model; <-- this line throws error

            return new PartialViewResult()
            {
                ViewName = viewName,
                ViewData = viewData,
                TempData = tempData
            };
        }
    }

and the problem here is that i got an error

System.InvalidOperationException: 'The model item passed into the ViewDataDictionary is of type 'RazorPages.PartialViews.CustomerDetailViewModel', but this ViewDataDictionary instance requires a model item of type 'RazorPages.Pages.CustomersModel'.'

So the ViewData are bind to the CustomerModel, it is possible to return partial view specific ViewModel ?

The bottom line question is, should I approach Razor Pages as an replacement for the MVC or they are intended for less complicated projects than MVC ?

Mike Brind · Accepted Answer · 2019-04-16T10:24:10.723

In response to the technical issue, try this version of your method:

public static class PartialViewHelper
{
    public static PartialViewResult PartialView<T>(string viewName, object model, ViewDataDictionary viewData, ITempDataDictionary tempData)
    {
        return new PartialViewResult()
        {
            ViewName = viewName,
            ViewData = new ViewDataDictionary<T>(viewData, model),
            TempData = tempData
        };
    }
}

Then call it as follows (although the name of the partial view doesn't look right to me):

var partialView = PartialViewHelper.PartialView<PartialViews.CustomerDetailViewModel>("/PartialViews/CustomerDetailViewModel.cs", model, ViewData, TempData);

And in reply to the bottom line question, Razor Pages builds on MVC. Anything that you can do with MVC, you can also do with Razor Pages. It is intended to replace MVC for server-side generation of HTML. You can build as complicated an application as you like with it. But your code will likely be a lot simpler than an equivalent MVC application, which is a good thing, right?

Thank you, your version is working :) however, I was unable to run the `ToStringExtension()`. I will try to fix it later. Now I was able to get html from partial view with `ViewRenderService` i found on SO https://stackoverflow.com/a/39400153/2333663. So I will try new project in Razor Pages then :) — Muflix, Apr 23 '19 at 20:25

Return PartialView in JsonResult

1 Answers1