How do you use RegisterFactory?

user_1522446 0
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I am having problems understanding how to use RegisterFactory. The code below works fine with the older InjectionFactory but I am having problems when I try to do the same thing with RegisterFactory.

In the sample code there is an uncommented section that uses RegisterFactory and a commented section that uses InjectionFactory. The InjectionFactory code works fine but the RegisterFactory throws an ResolutionFailedException. Unity.ResolutionFailedException: 'The current type, ConsoleApp1.IFoo, is an interface and cannot be constructed. Are you missing a type mapping?

What am I doing incorrectly?

class Program
{
    static void Main(string[] args)
    {
        var container = new UnityContainer();
        container.EnableDebugDiagnostic();

        container.RegisterType<IFoo, Foo1>("Foo1");
        container.RegisterType<IFoo, Foo2>("Foo2");

        container.RegisterType<MainViewModel>();

        // This does not work
        container.RegisterFactory<Func<string, IFoo>>((c, type, name) => c.Resolve<IFoo>(name));

        // This works
        //container.RegisterType<Func<string, IFoo>>(new InjectionFactory(
        //    ctx => new Func<string, IFoo>(name => container.Resolve<IFoo>(name))));


        var vm = container.Resolve<MainViewModel>();
    }
}

public class MainViewModel
{
    public MainViewModel(Func<string, IFoo> fooFactory)
    {
        var foo1 = fooFactory.Invoke("Foo1");
        var foo2 = fooFactory.Invoke("Foo2");
    }
}

public interface IFoo
{
    string Name { get; }
}

public class Foo1 : IFoo
{
    public string Name { get; set; }

    public Foo1()
    {
        Name = "Foo1";
    }
}

public class Foo2 : IFoo
{
    public string Name { get; set; }

    public Foo2()
    {
        Name = "Foo2";
    }
}
unity-container
1 Answers

If you're registering with RegisterFactory, you tell Unity how to construct the instance. But Unity already knows how to construct Foo1 and Foo2, because you registered those already.

What you want is a factory for you to use, that's what RegisterType does, so this works.

Normally, such a factory would implement some IFooFactory, thus making the context more obvious. But as long as Func<string, IFoo> is registered only used once, it works fine, too, of course.

user_57584200
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