PartialView() does not return a View with a underscore

Question

TemplateController:

this works:

 return PartialView("_Create");

but this does not work:

return PartialView();

The asp.net mvc convention should actually check a View folder with the name of the controller => "Template" and check for a View the same name as the action => "Create".

This is valid for a return View(). Why does a return PartialView() not just consider the underscore?

Answer 1

This answer is specifically for ASP.NET MVC5. It may require slight modification to work with other version of MVC but it should generally be applicable.

To have return Partial(model) respect underscores on partial names, you need a custom view engine. Fortunately this is an exceedingly trivial custom view engine.

public class CustomRazorViewEngine : RazorViewEngine
{
    public CustomRazorViewEngine()
    {
      var underScored = new[] { "~/Views/{1}/_{0}.cshtml", "~/Views/{1}/_{0}.vbhtml" }

      PartialViewLocationFormats = underScored.Union(PartialViewLocationFormats).ToArray();
    }
}

The following format is the default patterns for Shared views:

~/Views/Shared/{0}.cshtml
~/Views/Shared/{0}.vbhtml

You could include alternates for these too if you wish. If you specifically want to only serve files with the underscore, remove the union and merely use: PartialViewLocationFormats = underScored;

This is with the razor view engine, I assume it would be comparable with the webforms view engine if that's your engine of choice.

Lastly you need to register this to be the view engine:

public class Startup
{
    public void Configuration(IAppBuilder app)
    {
        //View Engines
        ViewEngines.Engines.Remove(ViewEngines.Engines.Single(x => x is RazorViewEngine));
        ViewEngines.Engines.Add(new CustomRazorViewEngine());

The Startup class is specific to MVC5, this would vary slightly between versions. You could use App_Start files with webactivator or the global.asax in other versions.