Multiplechoicetrainer/MultipleChoiceTrainer/Controllers/QuizController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using MultipleChoiceTrainer.Data;
using MultipleChoiceTrainer.Models;
using MultipleChoiceTrainer.Models.DataModels;

namespace MultipleChoiceTrainer.Controllers
{
    public class QuizController : Controller
    {
        private readonly ApplicationDbContext _context;

        public QuizController(ApplicationDbContext context)
        {
            _context = context;
        }

        public IActionResult Section(int id)
        {
            var vm = new QuizViewModel()
            {
                QuizType = QuizType.Section,
                CurrentTypeId = id
            };

            GetQuestion(vm);

            return Quiz(vm);
        }

        public IActionResult Category(int id)
        {
            var vm = new QuizViewModel()
            {
                QuizType = QuizType.Category,
                CurrentTypeId = id
            };
            GetQuestion(vm);

            return Quiz(vm);
        } 

        private void GetQuestion(QuizViewModel vm)
        {
            var questions = _context.Questions.Include(e => e.Section).ThenInclude(e => e.Category).Include(e => e.Choices).Include(e => e.Answers).AsQueryable();

            switch(vm.QuizType)
            {
                case QuizType.Category:
                    questions = questions.Where(e => e.Section.CategoryId == vm.CurrentTypeId);
                    break;
                case QuizType.Section:
                    questions = questions.Where(e => e.SectionId == vm.CurrentTypeId);
                    break;
            }

            questions = questions.ToList().AsQueryable();
            questions = questions.OrderByDescending(e => e.Answers.Count());
            questions = questions.Take(10);

            var rnd = new Random();
            vm.CurrentQuestion = questions.ElementAt(rnd.Next(0, questions.Count() - 1));

            vm.Choices = vm.CurrentQuestion.Choices.Select(oc => new Choice() { Id = oc.Id, Text = oc.Text }).ToList();
        }

        public IActionResult Quiz(QuizViewModel viewModel)
        {


            return View("quiz", viewModel);
        }
    }
}