public ActionResult Post([FromBody] UserReview newItem) { if (newItem is null) { return(BadRequest()); } var existing = _criticReviewService .AsQueryable() .Where(x => x.BookId == newItem.BookId && x.UserId == newItem.BookId) .FirstOrDefault(); if (existing != null) { return(BadRequest("User already reviewed this book!")); } var item = _criticReviewService.AddUserReview(newItem); return(Ok(item)); }