public ActionResult AddReview(string isbn) { AccessToken accessToken = ((AccessToken)Session["AccessToken"]); if (rentalManager.GetRentalByCustomerID(accessToken.User.CustomerID, isbn) == null) { Session["Error"] = "Please check out the book before leaving a review"; return(RedirectToAction("Reviews", "Reviews", new { isbn })); } Session["Error"] = ""; if (reviewManager.CheckReview(accessToken.User.CustomerID, isbn)) { ViewBag.Content = reviewManager.GetReviewByCustomerBook(accessToken.User.UserName, isbn, Active.active).Content; } ViewBag.ISBN = isbn; return(View()); }