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 w

Answer 1

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();
}