WebAPI ActionFilterAttribute OnExecuting not firing

Question

I have the following Web API ActionFilterAttribute

namespace namespace.Filters {

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Web.Http.Controllers;
    using System.Web.Http.Filters;

    public class LogApiRequestActionFilterAttribute : ActionFilterAttribute {

        public LogApiRequestActionFilterAttribute() {
        }

        private void logData(HttpActionContext actionContext) {
            var controllerName = actionContext.ActionDescriptor.ControllerDescriptor.ControllerType.FullName;
            var actionName = actionContext.ActionDescriptor.ActionName;
            var parameters = "";

            foreach (var item in actionContext.ActionArguments) {
                parameters += string.Format("{0} = {1}, ", item.Key, item.Value);
            }

            if (parameters.Any()) {
                parameters = parameters.Remove(parameters.Count() - 2);
            }

            var message = string.Format("{0}.{1}({2})", controllerName, actionName, parameters);
            // Do the logging
        }

        public override void OnActionExecuting(HttpActionContext actionContext) {
            logData(actionContext);
            base.OnActionExecuting(actionContext);
        }
    }
}

When I add it globally over the WebApiConfig.cs like this:

config.Filters.Add(new LogApiRequestActionFilterAttribute());

But the logData method never gets called. Does anyone know why?

Answer 1

Did you decorate your controller (or any action method), with that filter ?

For e.g.

1. After creating a filter called LogApiRequestActionFilterAttribute, you need to register it (as you have done).
2. After registration, if the filter has to be applied at the controller level, then decorate your controller with that filter.

3. If the filter has to be applied only on certain action method, put the filter on that particular action method(s)

   [LogApiRequestActionFilter]
    public class YourController : ApiController
    { //--->controller level filter
       [LogApiRequestActionFilter] //-->action level filter
       public IHttpActionResult DoAction()
       {
   
       }
   
    }
   

4. If neither of them works out, when the action method executes, put a breakpoint and analyse the http request. Check If your filter is registered or not

Answer 2

I just found my problem, thanks a lot to now he who must not be named.

My filter was properly registered and also perfectly loaded, just the method I was testing AND debugging with, wasn't called with a request. It was called from an razor helper and there the Request-property is null of course.

So the fix is to use an action which is called with an http request and not just as normal method call.