public override void OnActionExecuting(ActionExecutingContext filterContext) { CaptchaValidator recaptchaValidator = new CaptchaValidator { ChallengeValue = filterContext.HttpContext.Request.Form["captcha_challenge_field"], ResponseValue = filterContext.HttpContext.Request.Form["captcha_response_field"], ClientKey = GetClientKey(filterContext) }; if (recaptchaValidator.ShouldValidate()) { bool valid = recaptchaValidator.Validate(); if (!valid) { InvalidateClientKey(filterContext); } filterContext.ActionParameters["captchaValid"] = valid; base.OnActionExecuting(filterContext); } }