Ninject Factory Derived Types

Question

I watch the Ninject Factory extension at the following link: http://www.planetgeek.ch/2011/12/31/ninject-extensions-factory-introduction/

I'm trying to wrap my head around an extension and see if it really fits into what I'm trying to do.

Can a Factory extension create different types based on a passed parameter?

Example:

class Base {} class Foo : Base {} class Bar : Base {} interface IBaseFactory { Base Create(string type); } kernel.Bind<IBaseFactory>().ToFactory(); 

What I want to do is:

 factory.Create("Foo") // returns a Foo factory.Create("Bar") // returns a Bar factory.Create("AnythingElse") // returns null or throws exception? 

Can this extension do this or is this not one of the intended uses?

Answer 1

Of course. You can use your own instance provider.

  [Fact] public void CustomInstanceProviderTest() { const string Name = "theName"; const int Length = 1; const int Width = 2; this.kernel.Bind<ICustomizableWeapon>().To<CustomizableSword>().Named("sword"); this.kernel.Bind<ICustomizableWeapon>().To<CustomizableDagger>().Named("dagger"); this.kernel.Bind<ISpecialWeaponFactory>().ToFactory(() => new UseFirstParameterAsNameInstanceProvider()); var factory = this.kernel.Get<ISpecialWeaponFactory>(); var instance = factory.CreateWeapon("sword", Length, Name, Width); instance.Should().BeOfType<CustomizableSword>(); instance.Name.Should().Be(Name); instance.Length.Should().Be(Length); instance.Width.Should().Be(Width); } private class UseFirstParameterAsNameInstanceProvider : StandardInstanceProvider { protected override string GetName(System.Reflection.MethodInfo methodInfo, object[] arguments) { return (string)arguments[0]; } protected override Parameters.ConstructorArgument[] GetConstructorArguments(System.Reflection.MethodInfo methodInfo, object[] arguments) { return base.GetConstructorArguments(methodInfo, arguments).Skip(1).ToArray(); } }