Recognize if the client is requesting page or something else in ASP.NET MVC custom HttpModule?

I have written custom HttpModule that does something every time RequestEnd event gets fired.

public void Init(HttpApplication context) {
    context.End开发者_Python百科Request += EndEventHandler;
}

But I want it to do something only when EndRequest event is fired for the request of a html page. Not when it is a request for CSS file, picture or something else. How can I recognize what kind of content is being requested in that particular request so that I can decide what to do ?

Note: I guess similar question has been asked before but I cannot find it please add to possible duplicates if you can.

EDIT: To be more exact, I want to take some steps during the end of request if that request was processed by controller action (hmm when I think about it now maybe action filter that gets called for all actions would be better then module - is there some kind of filter that is not called when redirect action is returned?).

You can look at the content type:

if (HttpContext.Current.Response.ContentType == "text/html")
{
    ... you will be returning an HTML
}

if (HttpContext.Current.Request.Url.AbsolutePath.EndsWith(".html"))
{
    ... it was a static html page that was requested
}

UPDATE:

Alright, I've just noticed that your question was tagged with asp.net-mvc. At first when I saw an HttpModule I thought you were doing a normal ASP.NET application (I couldn't even imagine an HttpModule in an MVC application).

Now that this has been clear you obviously could use a global action filter in which you can override the OnActionExecuting and OnActionExecuted methods which will be invoked respectively before and after a controller action is executed.

As far as your question about the redirect action in the OnActionExecuted method you could look at the filterContext.Result and see if it is a RedirectToRouteResult type:

public class MyActionFilter : ActionFilterAttribute
{
    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        base.OnActionExecuted(filterContext);
        if (!(filterContext.Result is RedirectToRouteResult))
        {
            ...
        }
    }
}