SqlNullValueException：数据为 Null。无法在 ASP.NET Core 6 MVC 项目中的 Null 值错误上调用此方法或属性

Question

我正在开发一个 ASP.NET Core 6 MVC 项目并收到此屏幕截图中显示的错误：

这是我的作业，所以任何帮助将不胜感激。

我试图更改 controller 和存储库，但没有任何改变。 代码如下 - ClubController ：

using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using webHomework.Data;
using webHomework.Interfaces;
using webHomework.Models;
using webHomework.ViewModels;

namespace webHomework.Controllers
{
    public class ClubController : Controller
    {
        private readonly IClubRepository _clubRepository;
        private readonly IPhotoService _photoService;

        public ClubController(IClubRepository clubRepository, IPhotoService photoService)
        {
            _clubRepository = clubRepository;
            _photoService = photoService;
        }      

        public async Task<IActionResult> Index()
        {
            IEnumerable<Club> clubs = await _clubRepository.GetAll();
            return View(clubs);
        }

        public async Task<IActionResult> Detail(int id)
        {
            Club club = await _clubRepository.GetByIdAsync(id);
            return View(club);
        }

        public IActionResult Create()
        {
            return View();
        }

        [HttpPost]
        public async Task<IActionResult> Create(CreateClubViewModel clubVM)
        {
            if (ModelState.IsValid)
            {
                var result = await _photoService.AddPhotoAsync(clubVM.Image);

                var club = new Club
                {
                    Title = clubVM.Title,
                    Description = clubVM.Description,
                    Image = result.Url.ToString(),
                    Address = new Address
                    {
                        Street = clubVM.Address.Street,
                        City = clubVM.Address.City,
                        State = clubVM.Address.State,
                    }
                };

                _clubRepository.Add(club);

                return RedirectToAction("Index");
            }
            else
            {
                ModelState.AddModelError("", "Photo upload failed");
            }

            return View(clubVM);
        }
    }
}

ClubRepository ：

using Microsoft.EntityFrameworkCore;
using webHomework.Data;
using webHomework.Interfaces;
using webHomework.Models;

namespace webHomework.Repository
{
    public class ClubRepository : IClubRepository
    {
        private readonly ApplicationDbContext _context;

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

        public bool Add(Club club)
        {
            _context.Add(club);
            return Save();
        }

        public bool Delete(Club club)
        {
            _context.Remove(club);
            return Save();
        }

        public async Task<IEnumerable<Club>> GetAll()
        {
            return await _context.Clubs.ToListAsync();
        }

        public async Task<Club> GetByIdAsync(int id)
        {
            return await _context.Clubs.Include(i => i.Address).FirstOrDefaultAsync(i => i.Id == id);
        }

        public async Task<IEnumerable<Club>> GetClubByCity(string city)
        {
            return await _context.Clubs.Where(c => c.Address.City.Contains(city)).ToListAsync();
        }

        public bool Save()
        {
            var saved = _context.SaveChanges();
            return saved > 0 ? true : false;
        }

        public bool Update(Club club)
        {
            _context.Update(club);
            return Save();
        }
    }
}

Answer 1

将映射到数据库编号字段的int属性声明为可空的int? .