Castle Windsor BuildUp

Does Castle Windsor have an equivalent to Unity's BuildUp() whereby you can decorate class properties with attributes and have the container pass in values to an existing object instance?

e.g. in Unity:

Statistics existingInstance = new Statistics();  
container.BuildUp(existingInstance)

class Statistics  
{  
  [Dependency]  
开发者_运维技巧  public ICalculator Calculator { get; set; }  

You can however code this functionality yourself. For example, here is an ASP.NET MVC FilterAttributeFilterProvider, used to inject proprties onto attribute action filters.

  public class AttributeFilterProvider : FilterAttributeFilterProvider
  {
    public AttributeFilterProvider(IKernel kernel)
    {
      _kernel = kernel;
    }

    private readonly IKernel _kernel;

    protected override IEnumerable<FilterAttribute> GetControllerAttributes(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
    {
      var attributes = base.GetControllerAttributes(controllerContext, actionDescriptor);
      BuildUpAttributeDependancies(attributes);
      return attributes;
    }

    protected override IEnumerable<FilterAttribute> GetActionAttributes(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
    {
      var attributes = base.GetActionAttributes(controllerContext, actionDescriptor);
      BuildUpAttributeDependancies(attributes);
      return attributes;
    }

    private void BuildUpAttributeDependancies(IEnumerable<FilterAttribute> attributes)
    {
      foreach (var attribute in attributes)
      {
        var propInfos = attribute.GetType().GetProperties().Where(x => x.GetValue(attribute) == null).AsEnumerable();
        foreach (var pi in propInfos)
        {
          if (_kernel.HasComponent(pi.PropertyType))
          {
            var service = _kernel.Resolve(pi.PropertyType);
            pi.SetValue(attribute, service);
          }
        }
      }
    }
  }

In the BuildUpAttributeDependancies method, we look for un-initialised (null) properties, and then check to see if the type has been registered with Castle Windsor. If it has, we set the property.

By replacing the default FilterAttributeFilterProvider with our custom one (above) in the global.asax file we can now use Castle Windsors DI features to inject any type onto any Action Filter in our MVC application. To complete this answer fully, here is an example of a global.asax application class with Castle Windsor setup for both Controller (at instantiation time) and ActionFilter (at usage time) dependancy injection:

public class MvcApplication : System.Web.HttpApplication
{
  private static IWindsorContainer _container;

  private static void BootstrapContainer()
  {
    _container = new WindsorContainer()
        .Install(FromAssembly.This());

    var controllerFactory = new ControllerFactory(_container.Kernel);
    ControllerBuilder.Current.SetControllerFactory(controllerFactory);
  }

  private static void BootstrapFilters()
  {
    var oldProvider = FilterProviders.Providers.Single(f => f is FilterAttributeFilterProvider);
    FilterProviders.Providers.Remove(oldProvider);

    var provider = new AttributeFilterProvider(_container.Kernel);
    FilterProviders.Providers.Add(provider);
  }

  protected void Application_Start()
  {
    AreaRegistration.RegisterAllAreas();

    WebApiConfig.Register(GlobalConfiguration.Configuration);
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    BundleConfig.RegisterBundles(BundleTable.Bundles);

    BootstrapContainer();
    BootstrapFilters();
  }
}

looks like the answer is that Castle Windsor can't inject dependencies into an existing object instance either by attributes or an injection method:

Duplication Question