public void Create(DalQuiz entity)
        {
            Quiz test = new Quiz() { Title = entity.Title, CategoryId = entity.Category.Id };

            test.Questions = entity.Questions.Select(question => new QuizQuestion()
            {
                Text = question.Text,
                AnswerOptions = question.AnswerOptions.Select(answer => new AnswerOption()
                {
                    Text = answer,
                    IsCorrect = answer == question.CorrectAnswer ? true : false
                }).ToList()
            }).ToList();

            context.Set<Quiz>().Add(test);
        }
        // Clear
        public void Update(DalQuiz entity)
        {
            Quiz test = context.Set<Quiz>().FirstOrDefault(t => t.Id == entity.Id);

            if (test != null)
            {
                test.Questions.Clear();
                test.CategoryId = entity.Category.Id;
                test.Title = entity.Title;
                test.Questions = entity.Questions.Select(question => new QuizQuestion()
                {
                    Text = question.Text,
                    AnswerOptions = question.AnswerOptions.Select(answer => new AnswerOption()
                    { 
                        Text = answer,
                        IsCorrect = answer == question.CorrectAnswer ? true : false
                    }).ToList(),
                }).ToList();
            }
        }