public async Task <IActionResult> AddReview([FromBody] Review model)
        {
            var user = await _userManager.GetUserAsync(User);

            if (user == null)
            {
                return(NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'."));
            }
            var userReview = new Review
            {
                RecallDifficulty = model.RecallDifficulty,
                AppUser          = user,
                ReviewDate       = DateTime.UtcNow,
                LearningItemID   = model.LearningItemID
            };

            _repository.AddReview(userReview);
            return(Ok());
        }