Change ServiceOverride after component registration in Castle - castle-windsor

Question

I have two components registered for a service:
container.Register(
Component.For<IDataStorage>().Named("FirstChoice").ImplementedBy...
Component.For<IDataStorage>().Named("SecondChoice").ImplementedBy
Then I have a set of components deriving from this base class, that depends on those components:
public abstract class BaseMessageHandler
{
public IDataStorage FirstStorage {get; set;}
public IDataStorage SecondStorage {get; set;}
}
If I was registering these "handlers" (deriving from BaseMessageHandler) manually, I would specify a service override, indicating which component I want for properties "FirstStorage" and "SecondStorage". Something like:
.Configure(x => x.DependsOn(
ServiceOverride.ForKey("FirstStorage").Eq("FirstChoice"),
ServiceOverride.ForKey("SecondStorage").Eq("SecondChoice"))
Unfortunately, this registration is done automatically by a framework (NServiceBus). I know that if I register the handlers first (before NServiceBus has a chance to do so), these registrations will stick. But rather than try to guess and mimick the registration NServiceBus does, I wonder if I can specify service overrides in a custom IContributeComponentModelConstruction.
It seems a good place to do so, and I'm able to find these properties:
public class DataStorageOverrideContributor : IContributeComponentModelConstruction
{
public void ProcessModel(Castle.MicroKernel.IKernel kernel, Castle.Core.ComponentModel model)
{
var dataStorageDependencies = model.Properties.Where(
x => x.Dependency.TargetItemType == typeof(IDataStorage));
foreach (var propertyDependency in dataStorageDependencies)
{
// now what??
but I'm not sure the proper way to:
check if a service override is already specified (in which case I would do nothing)
add a service override to a property dependency.
Is this something that could be done inspecting and working the ComponentModel in the IContributeComponentModelConstruction.ProcessModel method?

Answer 1

I would use a subdependency resolver in your scenario. You can see the code below on how to use it.
Goodluck,
Marwijn.
public interface IDataStorage
{
}
public class DataStore1 : IDataStorage
{
}
public class DataStore2 : IDataStorage
{
}
public class BaseMessageHandler
{
public IDataStorage FirstStorage { get; set; }
public IDataStorage SecondStorage { get; set; }
}
public class SubDependencyResolver : ISubDependencyResolver
{
private readonly IKernel _kernel;
public SubDependencyResolver(IKernel kernel)
{
_kernel = kernel;
}
public bool CanResolve(CreationContext context, ISubDependencyResolver contextHandlerResolver, ComponentModel model,
DependencyModel dependency)
{
return model.Implementation == typeof (BaseMessageHandler) && dependency.TargetType == typeof(IDataStorage);
}
public object Resolve(CreationContext context, ISubDependencyResolver contextHandlerResolver, ComponentModel model,
DependencyModel dependency)
{
var handlers = _kernel.GetHandlers(dependency.TargetType);
switch (dependency.DependencyKey)
{
case "FirstStorage":
return handlers.Single(h => h.ComponentModel.Implementation == typeof (DataStore1)).Resolve(context);
case "SecondStorage":
return handlers.Single(h => h.ComponentModel.Implementation == typeof(DataStore2)).Resolve(context);
}
return null;
}
}
[TestFixture]
public class Tests
{
[Test]
public void SomeTest()
{
var container = new WindsorContainer();
container.Kernel.Resolver.AddSubResolver(new SubDependencyResolver(container.Kernel));
container.Register(
Component.For<IDataStorage>().Named("FirstChoice").ImplementedBy<DataStore1>(),
Component.For<IDataStorage>().Named("SecondChoice").ImplementedBy<DataStore2>(),
Component.For<BaseMessageHandler>()
);
var messageHandler = container.Resolve<BaseMessageHandler>();
Assert.AreEqual(typeof(DataStore1), messageHandler.FirstStorage.GetType());
Assert.AreEqual(typeof(DataStore2), messageHandler.SecondStorage.GetType());
}
}
alternative you may use:
case "FirstStorage":
return handlers.Single(h => h.ComponentModel.Name == "FirstChoice").Resolve(context);
case "SecondStorage":
return handlers.Single(h => h.ComponentModel.Name == "SecondChoice").Resolve(context);
to resolve on component name rather then implementation type.