I have a service IService and an implementation StrategyService like that:
interface IService
{
// interface declaration here
}
class StrategyService: IService
{
IService[] services;
StrategyService(params IService[] services)
{
this.services = services;
}
// interface implementation here
}
Now let's say I have 2 implementations of IService: Service1 & Service2. I want to tell Castle Windsor to take instances of Service1 and Service2 as parameters for the component StrategyService.
Here is my test:
var container = new WindsorContainer();
container.Kernel.Resolver.AddSubResolver(new CollectionResolver(container.Kernel));
container.Register(
Component.For<IService>().Instance(new Service1()).Named("service1"),
Component.For<IService>().Instance(new Service2()).Named("service2"),
Component.For<IService>().ImplementedBy<StrategyService>());
var service = container.Resolve<IService>();
// `service` is of type `Service1`
How can I get an instance of StrategyService with service1 and service2 as parameters?
Just invert the declaration of the components like this:
container.Register(
Component.For<IService>().ImplementedBy<StrategyService>(),
Component.For<IService>().Instance(new Service1()).Named("service1"),
Component.For<IService>().Instance(new Service2()).Named("service2"));
There is some magic here, has it seems to resolve the first component declared, but use only the two next ones excluding that first into the array to be injected.
Related
My application uses the "SignalR" client/server comms framework. If you aren't familiar with it, the server-side app typically contains one or more "hub" classes (similar to asmx web services), each providing methods that can be called by a client. During startup, the client needs to first create a connection, then create a "proxy" for each hub that it will need to talk to, e.g.:-
var hubConnection = new HubConnection("http://...");
var fooHubProxy = hubConnection.CreateHubProxy("FooHub");
var barHubProxy = hubConnection.CreateHubProxy("BarHub");
...etc...
The string parameter passed to CreateHubProxy() is the name of the server-side hub class. The method return type is IHubProxy.
It feels like I should be able to utilise Windsor here, but I'm struggling to find a solution. My first thought was to instantiate the hub proxies and register these instances with Windsor (by name), e.g.
var fooHubProxy = hubConnection.CreateHubProxy("FooHub");
container.Register(Component.For<IHubProxy>().Instance(fooHubProxy).LifestyleSingleton().Named("FooHub"));
...etc...
The problem is that when a class needs a hub proxy, the only way to resolve it by name is to use service locator pattern, which isn't recommended. What other Windsor features (e.g. typed factories, etc.) might be useful here?
Edit
I've just found Windsor's .UsingFactoryMethod, and am wondering if this would work, to simplify hub registration:
container.Register(Component.For<IHubProxy>()
.UsingFactoryMethod((kernel, context) => hubConnection.CreateHubProxy("FooHub"))
.LifestyleSingleton()
.Named("FooHub"));
I guess I still have the problem of how to resolve by name though.
Two years later, but I have a more elegant solution for other people that stummble accross this problem too.
It is possible to use TypedFactory facility and adapt it to you needs like here.
first create the factory interface (only! no need for the actual implementation, castle will take care of that):
public interface IHubProxyFactory
{
IHubProxy GetProxy(string proxyName);
}
Now we need a class that extend the default typed facotory and retreives the component's name from the input (proxyName):
class NamedTypeFactory : DefaultTypedFactoryComponentSelector
{
protected override string GetComponentName(MethodInfo method, object[] arguments)
{
string componentName = null;
if (arguments!= null && arguments.Length > 0)
{
componentName = arguments[0] as string;
}
if (string.IsNullOrEmpty(componentName))
componentName = base.GetComponentName(method, arguments);
return componentName;
}
}
And then register the factory with castle and specify that your NamedTypeFactory will be used:
Component.For<IHubProxyFactory>().AsFactory(new NamedTypeFactory())
Now every class can get the factory interface in its constructor:
public class SomeClass
{
private IHubProxy _fooHub;
private IHubProxy _barHub;
public SomeClass(IHubProxyFactory hubProxyFactory)
{
_fooHub = hubProxyFactory.GetProxy("FooHub");
_barHub = hubProxyFactory.GetProxy("BarHub");
}
}
Okay, I think I've found a possible solution, partly using the approach detailed here which shows how it is possible to register Func<>s with Windsor.
First, I register a delegate (Func<>) that uses the container to resolve by name:-
Container.Register(Component.For<Func<string, IHubProxy>>()
.Instance(name => Container.Resolve<IHubProxy>(name))
.LifestyleSingleton());
Think of this as an IHubProxy "factory".
Next, I register my hub proxies as detailed in my original question:-
container.Register(Component.For<IHubProxy>()
.UsingFactoryMethod((kernel, context) => hubConnection.CreateHubProxy("FooHub"))
.LifestyleSingleton()
.Named("FooHub"));
container.Register(Component.For<IHubProxy>()
.UsingFactoryMethod((kernel, context) => hubConnection.CreateHubProxy("BarHub"))
.LifestyleSingleton()
.Named("BarHub"));
Here is an example of a class that needs instances of the hub proxies:-
public class SomeClass
{
private IHubProxy _fooHub;
private IHubProxy _barHub;
public SomeClass(Func<string, IHubProxy> hubProxyFactory)
{
_fooHub = hubProxyFactory("FooHub");
_barHub = hubProxyFactory("BarHub");
}
}
Untried so far, but it looks promising. It's a clever solution but injecting the Func<> feels a little hacky, so I would still be keen to hear of other possible solutions to my problem.
I just used a similar method to yours. I use a typed Factory. Advantage is I have type safety for my hubs. Registering the hubs is the same. The rest differs a bit but is technical the same.
IServiceFactory {
IHubProxy GetFooHub();
IHubProxy GetBarHub();
}
And Registration:
Container.AddFacility<TypedFactoryFacility>();
Container.Register(Component.For<IServiceFactory>().AsFactory());
Usage:
public class SomeClass
{
private IHubProxy _fooHub;
private IHubProxy _barHub;
public SomeClass(IServiceFactry hubProxyFactory)
{
_fooHub = hubProxyFactory.GetFooHub();
_barHub = hubProxyFactory.GetBarHub();
}
}
Btw. Factory.Get"Name"() resolves by name.
I'm experimenting with interception in Castle Windsor and notice that interceptors seem to be created as decorators of my service interface.
In other words, if I have an interface "ISomethingDoer" and a concrete "ConcreteSomethingDoer", the proxy implements ISomethingDoer but does not inherit from ConcreteSomethingDoer.
This is fine, and no doubt by design, but what I'm wondering is whether I can intercept protected virtual methods in my concrete classes that wouldn't be known by the public interface. I am doing this in order to add logging support, but I might want to log some of the specific internal details of a class.
In my slightly unimaginative test case I have this:
public interface ISomethingDoer
{
void DoSomething(int Count);
}
[Loggable]
public class ConcreteSomethingDoer : ISomethingDoer
{
public void DoSomething(int Count)
{
for (var A = 0; A < Count; A++)
{
DoThisThing(A);
}
}
[Loggable]
protected virtual void DoThisThing(int A)
{
("Doing a thing with " + A.ToString()).Dump();
}
}
So what I want to do is log calls to "DoThisThing" even though it's not part of the interface.
I've managed to get this working in Autofac. (I've created a Linqpad script here: http://share.linqpad.net/frn5a2.linq) but am struggling with Castle Windsor (see http://share.linqpad.net/wn7877.linq)
In both cases my interceptor is the same and looks like this:
public class Logger : IInterceptor
{
public void Intercept(IInvocation Invocation)
{
String.Format("Calling method {0} on type {1} with parameters {2}",
Invocation.Method.Name,
Invocation.InvocationTarget.GetType().Name,
String.Join(", ", Invocation.Arguments.Select(a => (a ?? "*null*").ToString()).ToArray())).Dump();
Invocation.Proceed();
"Done".Dump();
}
}
What I really want to do is say "any classes with a [Loggable] attribute, should use the logging interceptor". In the Autofac example I've specifically attached a logger to the registration, whereas with Castle I'm using an IModelInterceptorsSelector which looks like this:
public class LoggerInterceptorSelector : IModelInterceptorsSelector
{
public bool HasInterceptors(ComponentModel Model)
{
return Model.Implementation.IsDefined(typeof(LoggableAttribute), true);
}
public InterceptorReference[] SelectInterceptors(ComponentModel Model, InterceptorReference[] Interceptors)
{
return new[]
{
InterceptorReference.ForType<Logger>()
};
}
}
Finally, the code to execute all this is:
var Container = new WindsorContainer();
Container.Register(
Component.For<Logger>().LifeStyle.Transient
);
Container.Kernel.ProxyFactory.AddInterceptorSelector(new LoggerInterceptorSelector());
Container.Register(
Component.For<ISomethingDoer>()
.ImplementedBy<ConcreteSomethingDoer>()
.LifeStyle.Transient
);
var Doer = Container.Resolve<ISomethingDoer>();
Doer.DoSomething(5);
When run I would expect to see "Calling method DoThisThing with parameters x" for each time the method is called. Instead I only get the call to DoSomething logged.
I can see why Castle Windsor is doing this, but I'm wondering if there is a way to tweak the behaviour?
(As a side-note I don't want to use Windsor's own interceptor attributes as I don't want to introduce dependencies to Castle outside of my composition root.)
I have tried resolving the ConcreteSomethingDoer specifically and this works, but not if I'm resolving the ISomethingDoer.
Apologies for the long post, and also apologies because I am pretty new to Castle Windsor!
I you could register like:
Container.Register(
Component.For<ISomethingDoer, ConcreteSomethingDoer>()
.ImplementedBy<ConcreteSomethingDoer>()
.LifeStyle.Transient
);
This should create a class proxy by deriving from ConcreteSomethingDoer. However this won't work with dynamic interceptors. However you probably can work around that by creating a facility which registers the interceptor when needed.
I have following testing code trying to get one instance for generic and other for special purpose.
[TestMethod]
public void Test_Name_And_Named_Instances()
{
//MyClass implemented IMyClass
MyClass genericInstance = new MyClass("generic");
MyClass specialInstance = new MyClass("special");
IWindsorContainer container = new WindsorContainer();
container.Register(Component.For(IMyClass).Instance(genericInstance));
container.Register(Component.For(IMyClass).Instance(specialInstance).Named("special"));
IMyClass genericOne = container.Resolve<IMyClass>();
IMyClass specialOne = container.Resolve<IMyClass>("special");
Assert.AreSame(genericOne, genericInstance); //true
Assert.AreNotSame(genericOne, specialOne); //false
}
I expect to get two different instances, but the result is both genericOne and specialOne points to same objec genericInstance.
Any idea?
This doesn't compile:
container.Register(Component.For(IMyClass).Instance(genericInstance));
Should be:
container.Register(Component.For<IMyClass>().Instance(genericInstance));
Other than that, the test passes for me (Windsor 2.5.2)
EDIT:
If you flip the registrations, the test fails. This is by design. When you resolve without an explicit name, you're saying "give me the default component for this service", which in Windsor is the first registered component for that service type, by default.
If you need different components under the same service type, assign explicit names to all of them when registering and resolving.
How to register two services with one instance of implementation? I used:
_container.Register(Component.For(new [] { typeof(IHomeViewModel), typeof(IPageViewModel) }).
ImplementedBy(typeof(HomeViewModel)).Named("IHomeViewModel").LifeStyle.Singleton)
But upper code registers two instances of HomeViewModel.
That's exactly the way to do it. See "Type Forwarding" in the docs. It registers one logical component accessible via IHomeViewModel or IPageViewModel. The following test passes:
public interface IHomeViewModel {}
public interface IPageViewModel {}
public class HomeViewModel: IHomeViewModel, IPageViewModel {}
[Test]
public void Forward() {
var container = new WindsorContainer();
container.Register(Component.For(new[] {typeof (IHomeViewModel), typeof (IPageViewModel)})
.ImplementedBy(typeof(HomeViewModel)).Named("IHomeViewModel").LifeStyle.Singleton);
Assert.AreSame(container.Resolve<IHomeViewModel>(), container.Resolve<IPageViewModel>());
}
BTW you might want to use generics instead of all those typeof, and also remove the lifestyle declaration, since singleton is the default:
container.Register(Component.For<IHomeViewModel, IPageViewModel>()
.ImplementedBy<HomeViewModel>());
Is is possible to inject IPrincipal using Castle Windsor into my asp.net mvc controller. This article by Scott Hanselman has code in the comments to do it with structure map, but I cannot figure out how to do it with Castle.
Update:
Here is what I ended up with for my controller factory. Note that most of the code is from Steve Sanderson's Pro ASP.NET MVC book with the addition of the code from the answers below.
public class WindsorControllerFactory : DefaultControllerFactory
{
readonly WindsorContainer _container;
// The constructor:
// 1. Sets up a new IoC container
// 2. Registers all components specified in web.config
// 3. Registers IPrincipal
// 4. Registers all controller types as components
public WindsorControllerFactory()
{
// Instantiate a container, taking configuration from web.config
_container = new WindsorContainer(
new XmlInterpreter(new ConfigResource("castle"))
);
_container.AddFacility<FactorySupportFacility>();
_container.Register(Component.For<IPrincipal>()
.LifeStyle.PerWebRequest
.UsingFactoryMethod(() => HttpContext.Current.User));
// Also register all the controller types as transient
var controllerTypes = from t in Assembly.GetExecutingAssembly().GetTypes()
where typeof(IController).IsAssignableFrom(t)
select t;
foreach (var t in controllerTypes)
_container.AddComponentLifeStyle(t.FullName, t, LifestyleType.Transient);
}
// Constructs the controller instance needed to service each request
protected override IController GetControllerInstance(Type controllerType)
{
return (IController)_container.Resolve(controllerType);
}
}
If you're using Windsor 2.0, there's no need to modify the ControllerFactory:
var container = new WindsorContainer();
container.AddFacility<FactorySupportFacility>();
container.Register(Component.For<IPrincipal>()
.LifeStyle.PerWebRequest
.UsingFactoryMethod(() => HttpContext.Current.User));
// your component registrations...
This is just a wrapper around the Factory facility configuration. If you're using a previous version (RC3) you can configure this with XML too.
You try to let Windsor construct your IPrincipal where it has to just use the one that's there.
Inject it into the container through the AddComponentInstance method exposed by the MicroKernel in your ControllerFactory.
This would obviously require a custom ControllerFactory, but you should have that already.
I did something similar for HttpContext some time ago:
http://www.tigraine.at/2009/01/21/aspnet-mvc-hide-the-httpcontext-services-with-windsor-and-a-custom-controllerfactory/comment-page-1/#comment-2645
Your controller factory could look like this:
public IController CreateController(RequestContext requestContext, string controllerName)
{
container.Kernel.AddComponentInstance<IPrincipal>(typeof (IPrincipal),
System.Web.HttpContext.Current.User);
return (IController) container.Resolve(controllerName);
}
(Don't forget that your controllers have to be per-web-request or transient for this or you'll get in trouble)