MVC 4 Web API register filter

Question

I am using MVC 4 Web API to create a service layer for an application. I am trying to create a global filter that will act on all incoming requests to the API. Now I understan

Answer 1

The following should work. We actually use this for our web API project.

GlobalConfiguration.Configuration.Filters is of type HttpFilterCollection

 var filters = System.Web.Http.GlobalConfiguration.Configuration.Filters;
 filters.Clear();
 filters.Add(new ValidationActionFilterAttribute());

 public class ValidationActionFilterAttribute : FilterAttribute, IActionFilter, IFilter
 {
    ...
 }

Also, if you're working in a project that contains both MVC and WebAPI assembilies, could you check what's the namespace your ActionFilterAttribute's namespace. It's fairly confusing cause there are two ActionFilterAttributes under both:

  System.Web.Http.Filters
   System.Web.Http.Mvc

Source: Why is my ASP.NET Web API ActionFilterAttribute OnActionExecuting not firing?

It appears that you will need to have two filters, one for API and one for MVC. You can factor the common code into a separate class, and then just use the specific filter to call through to your common class, thus not violating DRY and essentially using the actual filters as wrappers which can be registered as filters.