What is an action filter?

Sometimes you want to perform logic either before an action method is called or after an action method runs. To support this, ASP.NET MVC provides action filters. Action filters are custom attributes that provide a declarative means to add pre-action and post-action behaviour to controller action methods. (From MSDN) More

How to implement a custom action filter

1. Inherit the abstract class ActionFilterAttribute and override the desired methods:

public class AdminAuthorize : ActionFilterAttribute
{
     public override void OnActionExecuting(ActionExecutingContext filterContext)
     {
           if (CheckYourConditon)
           { 
                // executing action 
                base.OnActionExecuting(filterContext); 
           } 
           else 
           { 
                 // Redirect to the needed login page or whatever you want 
                 // This can be pulled from config file or anything else 
                 filterContext.HttpContext.Response.Redirect("/error?ReturnUrl=" 
                 + HttpUtility.UrlEncode(filterContext.HttpContext.Request.RawUrl)); 
           } 
     }
}

1. Add the custom attribute to your controller/action

Controller:

[AdminAuthorize]
public partial class SendEmailController : Controller
{
...
}

Action:

[AdminAuthorize]
public virtual ActionResult Reset()
{
...
}

Membership integration

If you using ASP membership you can use Authorize attribute easily. You can use that to restrict the access to an action or a controller like this:

[Authorize(Roles="Admins")]

Or

[Authorize(Users="Admin")]