Action filters registration

One interesting side of MvcExtensions is dynamic action filters (IMvcFilter) registration for MVC controllers. This approach allows you to use filters as regular classes (not as attributes). In that case you will be able to inject your dependencies via constructor. To register filters you need to inherit from abstract class ConfigureFiltersBase:

public class ConfigureFilters : ConfigureFiltersBase
{
    public ConfigureFilters(IFilterRegistry registry) : base(registry) { }

    protected override void Configure()
    {
        Registry.Register<ProductController, PopulateCategories, PopulateSuppliers>(c => c.Create())
                .Register<ProductController, PopulateCategories, PopulateSuppliers>(c => c.Edit(0));
    }
}

Register with Boootstrapper:

//Global.asax.cs
public class MvcApplication : MvcExtensions.WindsorMvcApplication
{
    public MvcApplication()
    {
        Bootstrapper.BootstrapperTasks
            // ....
            .Include<ConfigureFilters>();
    }
}

As you can see, we register 2 action filters PopulateCategories and PopulateSuppliers for actions Create and Edit of ProductController.

Example of PopulateCategories class:

public class PopulateCategories : IMvcFilter, IActionFilter
{
    private readonly IRepository<Category> repository;
    
    public PopulateCategories(IRepository<Category> repository)
    {
        this.repository = repository;
    }

    public bool AllowMultiple { get { return false; } }

    public int Order { get; set; }

    public void OnActionExecuting(ActionExecutingContext filterContext) { }

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        ProductEditModel editModel = filterContext.Controller.ViewData.Model as ProductEditModel;

        if (editModel != null)
        {
            var categories = new SelectList(repository.All(), "Id", "Name", editModel.Category);
            filterContext.Controller.ViewData["categories"] = categories;
        }
    }
}

Read more http://weblogs.asp.net/rashid/archive/2010/05/27/mvcextensions-actionfilter.aspx