Return a partial view from a razor page Handler - asp.net-core

Question

I am having a problem returning a partial view from a razor page, my scenario is
I have a partial view which is a form and that has a model. I have 3 forms residing on a single razor pages
Form A post a ModelA
Form B post ModelB
My problem is, i want to handle thier specific post event on the parent Page which is a razor page.
How would i return this partial view
OnPostModelA(ModelA model)
{
if(! ModelState.IsValid)
return Partialview("_CreateModelA", model);
}
Is this possible using razor pages or this is not possible?
I just want to return the partialview with its designated model using ajax.

Answer 1

As you know ,Razor Pages have no equivalent PartialView method on the PageModel. If you do want to invoke different parial views in PageModel method , simply add a PartialView Helper Method in you PageModel:
[NonAction]
public virtual PartialViewResult PartialView(string viewName, object model)
{
ViewData.Model = model;
return new PartialViewResult()
{
ViewName = viewName,
ViewData = ViewData,
TempData = TempData
};
}
Here I use a ViewData.Model to store your model object , let's say your Model type is named as X1Model :
you can use it across the partial views .
Create a simple partial view named as _CreateModelA.cshtml :
#model HelloModel
AAAAA
<div>
#Model.Model.Welcome
</div>
and another partial view named as _CreateModelB.cshtml :
#model HelloModel
BBBBBBBB
<div>
#Model.Model.Welcome
</div>
At last , you can return PartialView in your PageModel:
public class HelloModel : PageModel
{
public X1Model Model { get; set; }
public ActionResult OnGet(int rand = 0)
{
var flag = rand % 2 == 0 ? true : false;
var model = new HelloModel() {
Model = new X1Model {
Welcome = "Hello,world",
}
};
if (flag)
{
return PartialView("_CreateModelA", model);
}
else
{
return PartialView("_CreateModelB", model);
}
}
[NonAction]
public virtual PartialViewResult PartialView(string viewName, object model)
{
// ...
}
}
Here's a screenshot :
However , it is not recommended to put partial view logic in PageModel . Using it in the Page file as below is much nicer:
#if(){
<partial name="" />
}else{
<partial name="" />
}

Answer 2

In asp dotnet core 2.2, Microsoft added a Partial method to the PageModel class that works similar to the PartialView method on the Controller class. It however doesn't allow you to pass ViewData to the view. So, if you need to do that, then you can create your own PartialViewResult like so:
var resultViewData = new ViewDataDictionary<YourModelType>(ViewData, model);
resultViewData[YourViewDataProperty] = yourViewDataValue;
return new PartialViewResult
{
ViewName = "_Branch",
ViewData = resultViewData,
TempData = TempData
};