Question

If I’ve got two properties in a class with the same interface type and I want to inject two different conrete types to each how do I do that with autofac either with Property or constructor injection.

eg.

class A : IA
{
    public IB PropertyB { get; set; }
    public IB PropertyC { get; set; }

    public A(IB b, IB c)
    {
        PropertyB = b;
        PropertyC = c;
    }

    public void PrintB()
    {
        PropertyB.Print();
    }

    public void PrintC()
    {
        PropertyC.Print();
    }
}

I’ve tried this but of course I just get a C inject into both properties

    var builder = new ContainerBuilder();

    builder.RegisterType<B>().As<IB>();
    builder.RegisterType<C>().As<IB>();
    builder.RegisterType<A>().As<IA>();

    var container = builder.Build();
    var a = container.Resolve<IA>();

Or this with the same result:

    builder.RegisterType<B>().As<IB>();
    builder.RegisterType<C>().As<IB>();
    builder.RegisterType<A>().As<IA>().PropertiesAutowired();

    var container = builder.Build();
    var a = container.Resolve<IA>();

Is there a way I can tell autofac that I want B in PropertyB and C in PropertyC ?

Answer 1

Using property injection, you can do the following:

builder.RegisterType<A>()
    .As<IA>()
    .OnActivating(e =>
{
    e.Instance.PropertyB = e.Context.Resolve<BImpl1>();
    e.Instance.PropertyC = e.Context.Resolve<BImpl2>();
});