Autofac Dependency Injection on Action Method Para

问题:

I have the following setup

public interface IObject 
{ 
    string Name { get; set;}
}

public class ConcreteObject : IObject 
{
    public string Name { get; set; }
}
public ActionResult Index(IObject myObject)
{        
    return View();
}

I have a concrete class which implements IObject, and I am using dependency injection to bind this concrete class to the interface.

Using Autofac, I have the following setup also

var builder = new ContainerBuilder();
builder.RegisterModule(new AutofacWebTypesModule());
builder.RegisterSource(new ViewRegistrationSource());
builder.RegisterFilterProvider();
builder.RegisterControllers(Assembly.GetExecutingAssembly()).InjectActionInvoker().PropertiesAutowired();
builder.RegisterModelBinders(Assembly.GetExecutingAssembly());
builder.RegisterModelBinderProvider();
builder.RegisterType<ExtensibleActionInvoker>().As<IActionInvoker>().WithParameter("injectActionMethodParameters", true);
builder.RegisterType<ConcreteObject>().As<IObject>().InstancePerHttpRequest();            
var container = builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

When I run this, I get an instance of the concrete class, but any paramaters that would usually be bound from the querystring are now null. ie: Home/Index?Name=test would bind an instance, but not bind the parameter Name. Is there a way to ensure that modelbinding still happens after DI?

回答1:

Edit: I do no recommend ever doing this, you should never inject interfaces into action methods!.

Ok, I have this solved. I set up a custom model binder which I call when an interface is present.

public class YourModelBinderProvider : IModelBinderProvider
{    
    public IModelBinder GetBinder(Type modelType)
    {
        if (modelType.IsInterface)
        {
            return new InterfaceModelBinder();
        }
        return null;
    }
}
public class InterfaceModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        ModelBindingContext context = new ModelBindingContext(bindingContext);
        var item = DependencyResolver.Current.GetService(bindingContext.ModelType);            

        Func<object> modelAccessor = () => item;
        context.ModelMetadata = new ModelMetadata(new DataAnnotationsModelMetadataProvider(),
            bindingContext.ModelMetadata.ContainerType, modelAccessor, item.GetType(), bindingContext.ModelName);

        return base.BindModel(controllerContext, context);
    }
}

Then in my global.asax I simply have

ModelBinderProviders.BinderProviders.Add(new YourModelBinderProvider());
var builder = new ContainerBuilder();            
builder.RegisterModelBinderProvider();
builder.RegisterType<ConcreteObject>().As<IObject>();    
var container = builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

回答2:

Despite that I don't understand what do you want to achieve using method injection, you can try to invoke TryUpdateModel method.