Custom Action Filters

ASP.NET MVC Action Filters

Here we look at creating custom Action Filters in ASP.NET MVC.

ActionFilterAttribute

When creating new custom action filters in ASP.NET MVC we need to create a class which inherits from ActionFilterAttribute. From this we can implement the following methods:

OnActionExecuting
OnActionExecuted
OnResultExecuting
OnResultExecuted

Here is a sample class which implements these methods:

using System.Web.Mvc;

namespace MVC_Practise.Controllers
{
    public class MyFirstCustomActionFilter : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            // do something

            base.OnActionExecuting(filterContext);
        }

        public override void OnActionExecuted(ActionExecutedContext filterContext)
        {
            // do something

            base.OnActionExecuted(filterContext);
        }

        public override void OnResultExecuting(ResultExecutingContext filterContext)
        {
            // do something

            base.OnResultExecuting(filterContext);
        }

        public override void OnResultExecuted(ResultExecutedContext filterContext)
        {
            // do something

            base.OnResultExecuted(filterContext);
        }
    }
}

With our newly ceated custom action filter we can now apply it to individual action methods or an entire controller classes (in which case every action method will use the attribute):

[MyFirstCustomActionFilter]
public ActionResult About()
{
    return View();
}

Applying our custom action filter to an action method called About results in the following order of methods firing:

OnActionExecuting
About
OnActionExecuted
OnResultExecuting
OnResultExecuted