Multiplechoicetrainer/MultipleChoiceTrainer/Controllers/SectionsController.cs

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

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

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

        // GET: Sections/Create
        public IActionResult Create(int? categoryId)
        {
            if(!categoryId.HasValue)
            {
                categoryId = _context.Categories.First().Id;
            }

            ViewData["CategoryId"] = new SelectList(_context.Categories, "Id", "Name", categoryId);
            return View();
        }

        // POST: Sections/Create
        // To protect from overposting attacks, enable the specific properties you want to bind to, for 
        // more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create([Bind("Id,Name,Description,CategoryId")] Section section)
        {
            if (ModelState.IsValid)
            {
                _context.Add(section);
                await _context.SaveChangesAsync();
                return RedirectToAction(nameof(Index), "Home", new { categoryId = section.CategoryId });
            }
            ViewData["CategoryId"] = new SelectList(_context.Categories, "Id", "Name", section.CategoryId);
            return View(section);
        }

        // GET: Sections/Edit/5
        public async Task<IActionResult> Edit(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var section = await _context.Sections.FindAsync(id);
            if (section == null)
            {
                return NotFound();
            }
            ViewData["CategoryId"] = new SelectList(_context.Categories, "Id", "Name", section.CategoryId);
            return View(section);
        }

        // POST: Sections/Edit/5
        // To protect from overposting attacks, enable the specific properties you want to bind to, for 
        // more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Edit(int id, [Bind("Id,Name,Description,CategoryId")] Section section)
        {
            if (id != section.Id)
            {
                return NotFound();
            }

            if (ModelState.IsValid)
            {
                try
                {
                    _context.Update(section);
                    await _context.SaveChangesAsync();
                }
                catch (DbUpdateConcurrencyException)
                {
                    if (!SectionExists(section.Id))
                    {
                        return NotFound();
                    }
                    else
                    {
                        throw;
                    }
                }
                return RedirectToAction(nameof(Index), "Home", new { categoryId = section.CategoryId });
            }
            ViewData["CategoryId"] = new SelectList(_context.Categories, "Id", "Name", section.CategoryId);
            return View(section);
        }

       
        private bool SectionExists(int id)
        {
            return _context.Sections.Any(e => e.Id == id);
        }
    }
}