Question

I defined 3 interfaces and 3 classes accordingly. Class A depends on interface B, interface B depends on interface C and a concrete class. My sample codes look like

public interface IA
{
}

public class A : IA
{
    private IB b;

    public A(IB b)
    {
        this.b = b;
    }
}

public interface IB
{
}

public class B : IB
{
    private IC c;
    private string myValue;

    public B(IC c, string myValue)
    {
        this.c = c;
        this.myValue = myValue;
    }
}

public interface IC
{
}

public class C : IC
{
}

The special thing is class B, the constructor requires both type and a string (concrete value).

        using (IUnityContainer container = new UnityContainer())
        {
            container.RegisterType<IB, B>()
                .RegisterType<IA, A>()
                .RegisterType<IC, C>();

            IA a = container.Resolve<IA>();
        }

How shall I define in code to instruct container to inject both IC and a string value to class B?

Answer 1

You can pass in an InjectionConstructor to your registration.

container.RegisterType<IB, B>(new InjectionConstructor(container.Resolve<IC>(), "myvalue-value"));