asp.net core mvc: split hosting and business-logic/ui into separate projects

Question

I want to separate my solution into at least two parts:

• Hosting-technology (Initializing Kestrel and setting up all the middleware, e.g. swashbuckle, authentication)
• Business-Logic & UI

because I want the hosting configuration to be replacable in later stages of the development process.

I tried simply moving all the folders containing controllers, models and views into a separate project, like shown in the image below:

Two projects with hosting configuration and business-logic separated:

So I

• moved those folders to the *.Implementation project
• added a nuget-reference to the package "Microsoft.AspNetCore.Mvc"
• referenced the *.Implementation project from the *.Host project
• added this class to the "Controllers"-folder in the *.Implementation project:

using Microsoft.AspNetCore.Mvc;

namespace MyApp.Implementation.Controllers
{
    public class ExampleController : Controller
    {
        public ActionResult<int> Index()
        {
            return 5;
        }
    }
}

If I start the application and open http://localhost:5000/example in my browser, I get the result "5" in my browser. This shows to me that the hosting technology finds my controller in the separate project.

But when I open http://localhost:5000 in the browser, I get an exception page telling me that the views for the Home-Controller where not found. The Console also shows the exception:

fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
System.InvalidOperationException: The view 'Index' was not found. The following locations were searched:
/Views/Home/Index.cshtml
/Views/Shared/Index.cshtml
/Pages/Shared/Index.cshtml

Since the webhost finds my controller, I would expect that it finds the views too. It seems not so.

How can I tell the webhost where to look for the views instead? Or do I need to do anything to them instead?

Answer 1

In addition to Kirk Larkin's comment to look at Application Parts in ASP.NET Core, you might also want to check out Razor Class Libraries.

I have not tried it myself yet, but it looks it might provide a solution for your issue.