Does a view exist in ASP.NET MVC? - asp.net-mvc

Question

Is it possible to determine if a specific view name exists from within a controller before rendering the view?
I have a requirement to dynamically determine the name of the view to render. If a view exists with that name then I need to render that view. If there is no view by the custom name then I need to render a default view.
I'd like to do something similar to the following code within my controller:
public ActionResult Index()
{
var name = SomeMethodToGetViewName();
// The 'ViewExists' method is what I've been unable to find.
if (ViewExists(name))
{
retun View(name);
}
else
{
return View();
}
}

Answer 1

private bool ViewExists(string name)
{
ViewEngineResult result = ViewEngines.Engines.FindView(ControllerContext, name, null);
return (result.View != null);
}
For those looking for a copy/paste extension method:
public static class ControllerExtensions
{
public static bool ViewExists(this Controller controller, string name)
{
ViewEngineResult result = ViewEngines.Engines.FindView(controller.ControllerContext, name, null);
return (result.View != null);
}
}

Answer 2

What about trying something like the following assuming you are using only one view engine:
bool viewExists = ViewEngines.Engines[0].FindView(ControllerContext, "ViewName", "MasterName", false) != null;

Answer 3

Here's another [not necessarily recommended] way of doing it
try
{
#Html.Partial("Category/SearchPanel/" + Model.CategoryKey)
}
catch (InvalidOperationException) { }

Answer 4

In asp.net core 2.x and aspnet6 the ViewEngines property no longer exists so we have to use the ICompositeViewEngine service. This a variant of the accepted answer using dependency injection:
public class DemoController : Controller
{
private readonly IViewEngine _viewEngine;
public DemoController(ICompositeViewEngine viewEngine)
{
_viewEngine = viewEngine;
}
private bool ViewExists(string name)
{
ViewEngineResult viewEngineResult = _viewEngine.FindView(ControllerContext, name, true);
return viewEngineResult?.View != null;
}
public ActionResult Index() ...
}
For the curious: The base interface IViewEngine is not registered as a service so we must inject ICompositeViewEngine instead. The FindView() method however is provided by IViewEngine so the member variable may use the base interface.

Answer 5

If you want to re-use this across multiple controller actions, building on the solution given by Dave, you can define a custom view result as follows:
public class CustomViewResult : ViewResult
{
protected override ViewEngineResult FindView(ControllerContext context)
{
string name = SomeMethodToGetViewName();
ViewEngineResult result = ViewEngines.Engines.FindView(context, name, null);
if (result.View != null)
{
return result;
}
return base.FindView(context);
}
...
}
Then in your action simply return an instance of your custom view:
public ActionResult Index()
{
return new CustomViewResult();
}

Answer 6

ViewEngines.Engines.FindView(ViewContext.Controller.ControllerContext, "View Name").View != null
My 2 cents.

Answer 7

Here's how to do it in Razor for Core 2.2 etc. Note that the call is "GetView", not "Find View)
#using Microsoft.AspNetCore.Mvc.ViewEngines
#inject ICompositeViewEngine Engine
...
#if (Engine.GetView(scriptName, scriptName, isMainPage: false).Success)
{
#await Html.PartialAsync(scriptName)
}