c# How to put a constraint on a generic Func argument that is within a method signature

Question

public void Test<TFeature>(Func<TController, ViewResult> controllerAction)                                          
            where TController : IController
            where TFeature : ISecurityFeature
        {
            ...
        }

I'm getting the error, Test does not define type parameter TController. How can I put a constraint on TController?

Answer 1

Unless you are defining it inside SomeClass<TController> (in which case you need to put constraint next to class SomeClass<TController>), you need to make TController a generic argument of your function, i.e.:

public void Test<TFeature, TController>(Func<TController, ViewResult> controllerAction)                                          
            where TController : IController
            where TFeature : ISecurityFeature
        {
            ...
        }

Answer 2

You need to add the TController as a generic parameter too

public void Test<TFeature, TController>(Func<TController, ViewResult> controllerAction)                                          
        where TController : IController
        where TFeature : ISecurityFeature
    {
        ...
    }