Simple way to calculate Response length in MVC4

Question

I was trying to calculate the length of a `HTTP Response`. Seems the stream doesn't want to play. (no read allowed. and the Content-Length doesn't seem set) I was hoping to simply call some length property on the `HttpContent` response. I have since googled and seen what looks to me like convoluted solutions around filters which I don't understand. Is it possible to access the length (content itself is option extra ) If not I would appreciate a link to an example for 'mvc4/.net 4.5 filter' included that I should work though till I do understand. :-) ``` public override void Init() { base.Init(); EndRequest += new EventHandler(EndRequestHandler); } public void EndRequestHandler(object sender, EventArgs e) { var admService = new AdminServices(); admService.HTTPTrace(Context); } public void HTTPTrace(HttpContext httpContext) { try { var eventTrace = new MasterEventTrace(); eventTrace.RemoteAddress = req.UserHostAddress; eventTrace.RequestLengthBytes = req.ContentLength; // var targetMemo…

Accepted Answer

You could write a custom Response filter:

```
public class ResponseLengthCalculatingStream: MemoryStream
{
    private readonly Stream responseStream;
    private long responseSize = 0;
    public ResponseLengthCalculatingStream(Stream responseStream)
    {
        this.responseStream = responseStream;
    }

public override void Write(byte[] buffer, int offset, int count)
    {
        this.responseSize += count;
        this.responseStream.Write(buffer, offset, count);
    }

public override void Flush()
    {
        var responseSize = this.responseSize;
        // Here you know the size of the response ...
        base.Flush();
    }
}
```

and register it in your `Global.asax`:

```
protected void Application_BeginRequest()
{
    Context.Response.Filter = new ResponseLengthCalculatingStream(Context.Response.Filter);
}
```

And if you wanted to apply this filter only on particular controller actions you could write a custom action filter instead of applying it in the BeginRequest event in Global.asax:

```
public class ResponseLengthCapturingAttribute: ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var response = filterContext.HttpContext.Response;
        response.Filter = new ResponseLengthCalculatingStream(response.Filter);
    }
}
```

and then all that's left is decorate the controller action with the corresponding action filter:

```
[ResponseLengthCapturing]
public ActionResult Index()
{
    ...
    return View();
}
```

Simple way to calculate Response length in MVC4

Solution

Problem