How do I pass variables to a custom ActionFilter in ASP.NET MVC app

Question

I have a controller in my MVC app for which I'm trying to log details using a custom ActionFilterAttribute, by using the onResultExecuted method.

I read this tutorial to understand and write my own action filter. The question is how do I pass variables from the controller to the action filter?

1. I want to get the input variables with which a controller is called. Say, the username/user ID.
2. If (in some situations) an exception is thrown by any controller method, I would want to log the error too.

The controller -

[MyActionFilter]
public class myController : ApiController {
    public string Get(string x, int y) { .. }
    public string somemethod { .. }
}

The action filter -

public class MyActionFilterAttribute : ActionFilterAttribute {
    public override void onActionExecuted(HttpActionExecutedContext actionExecutedContext) {
        // HOW DO I ACCESS THE VARIABLES OF THE CONTROLLER HERE
        // I NEED TO LOG THE EXCEPTIONS AND THE PARAMETERS PASSED TO THE CONTROLLER METHOD
    }
}

I hope I have explained the problem here. Apologies if I'm missing out some basic objects here, I'm totally new to this.

Answer 1

Approach - 1

Action Filter

public class MyActionFilter : ActionFilterAttribute
{
    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        base.OnActionExecuted(filterContext);
    }
}

Action Method

[MyActionFilter]
public ActionResult Index()
{
    ViewBag.ControllerVariable = "12";
    return View();
}

If you pay attention to the screenshot, you can see the ViewBag information

Approach - 2

Action Filter

public class MyActionFilter : ActionFilterAttribute
{
    //Your Properties in Action Filter
    public string Property1 { get; set; }
    public string Property2 { get; set; }

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        base.OnActionExecuting(filterContext);
    }
}

Action Method

[MyActionFilter(Property1 = "Value1", Property2 = "Value2")]
public ActionResult Index()
{
    return View();
}