Can't return Value Tuple from C# Class Library to ASP.net Core 2.1 MVC app

Question

I can't return Value Tuple from C# Class Library to ASP.net Core 2.1 MVC app, so I made a new solution to test only that point and it still did it.

Class Library (.net Framework 4.7):

namespace ClassLibrary1
{
    public class Class1
    {
        public (bool Success, string ReturnMessage) abc()
        {
            return (true, "hi");
        }
    }
}

.net Core 2.1 MVC Controller:

namespace WebApplication1.Controllers
{
    public class HomeController : Controller
    {
        public string Index()
        {
            var c = new Class1();
            var x = c.abc();
            return "";
        }
    }
}

I get this error in the MVC app at c.abc():

Reference to type 'ValueTuple<,>' claims it is defined in 'mscorlib', but it could not be found

If I create and return a Value Tuple within either project, it works.

I found this but it didn't help to install those Nuget packages (also why would that be required)? Predefined type 'System.ValueTuple´2´ is not defined or imported

How can I successfully call this from the MVC app?

Answer 1

you cannot call .Net Framework 4.7 class library from Asp.Net Core.

You can use .Net Standard, or ASP.Net Core for your Class Library.