Question

We are using Unity framework for Dependency injection. I am registerring two concrete implementations for same class. like…

container.RegisterType<IInterface, MyFirstClass>("first");
container.RegisterType<IInterface, MySecondClass>("second");

Now there are few classes which has contructer injection for above interface..

 public class Class1
    {
       private IInterface _myClass
       public Class1 (IInterface myClass)
       {
         _myClass = myClass // // should be instance of MyFirstClass
       }
 //.. other code
    }

   public class Class2
    {
       private IInterface _myClass

       public Class2 (IInterface myClass)
       {
         _myClass = myClass // should be instance of MySecondClass
       }
 //.. other code
    }

So now we want to resolve IInterface selectivly in above two classes. Class1 and Class2.

Class1 should be injeceted with MyFirstClass and Class2 should be injected with MyFirstClass. Is this possible to achieve via Unity framework? If not which other IoC frameworks support this?

Please suggest your opinions.

Answer 1

Try this

var container = new UnityContainer();
container.RegisterType<IInterface, MyFirstClass>("first");
container.RegisterType<IInterface, MySecondClass>("second");
container.RegisterType<Class1>(new InjectionConstructor(new ResolvedParameter(typeof(IInterface), "first")));
container.RegisterType<Class2>(new InjectionConstructor(new ResolvedParameter(typeof(IInterface), "second")));
var class1 = container.Resolve<Class1>();
Assert.IsInstanceOfType(class1.MyClass, typeof(MyFirstClass));
var class2 = container.Resolve<Class2>();
Assert.IsInstanceOfType(class2.MyClass, typeof(MySecondClass));

public class MyFirstClass : IInterface
{
}

public class MySecondClass : IInterface
{
}

public interface IInterface
{
}

public class Class1
{
  public IInterface MyClass { get; set; }
  public Class1(IInterface myClass)
  {
    MyClass = myClass;
  }
}
public class Class2
{
  public IInterface MyClass { get; set; }
  public Class2(IInterface myClass)
  {
    MyClass = myClass;
  }
}