運行程式時資料庫背景關系為空

我已經為此苦苦掙扎了半天。連接到我的資料庫時，我無法讓背景關系在我的應用程式中作業。如果我想添加/洗掉 dbset，我可以很好地連接到資料庫，但我無法弄清楚位于 SelectCharacter 檔案中的 dbcontext 有什么問題。

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;

namespace HeroesDB
{
    public class HeroesDBContext : DbContext
    {
        public static DbSet<HeroModels.Mage> Mages { get; set; }
        public static DbSet<HeroModels.Archer> Archers { get; set; }
        public static DbSet<HeroModels.Weapon> Weapons { get; set; }
        public static DbSet<HeroModels.Food> Foods { get; set; }
        public DbSet<UserRegistration.UserController> Users { get; set; }

        public HeroesDBContext()
        {

        }

        public HeroesDBContext(DbContextOptions options)
            : base(options)
        {

        }

        //add to allow migrations when the context is not built
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
                var builder = new ConfigurationBuilder()
                    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);

                var config = builder.Build();
                var cnstr = config["ConnectionStrings:HeroesDB"];
                var options = new DbContextOptionsBuilder<HeroesDBContext>().UseSqlServer(cnstr);
                optionsBuilder.UseSqlServer(cnstr);
            }
        }
    }
}

using Microsoft.Extensions.Configuration;

namespace Heroes
{
    public static class Program
    {
        public static IConfigurationRoot _configuration;

        /// <summary>
        ///  The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {

            var builder = new ConfigurationBuilder()
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);
            _configuration = builder.Build();


            SelectCharacter.CharacterSelection();
            Adventure.AdventureStart();

        }
    }



}

using HeroesDB;
using HeroModels;
using Microsoft.EntityFrameworkCore;
using SolutionItems;

namespace Heroes
{
    public partial class SelectCharacter
    {
        private static readonly HeroCreation heroCreation = new();
        private static readonly Mage mage = heroCreation.mage;
        private static readonly Archer archer = heroCreation.archer;
        public static IHero CurrentCharacter;

        private string _cnstr;
        private static DbContextOptionsBuilder _optionsBuilder;
        public SelectCharacter()
        {
            _cnstr = Program._configuration["ConnectionStrings:HeroesDB"];
            _optionsBuilder = new DbContextOptionsBuilder<HeroesDBContext>().UseSqlServer(_cnstr);
        }

        private static void RegisterUser()
        {
            using var context = new HeroesDBContext(_optionsBuilder.Options);
            
            var user = new UserRegistration.UserController();
            Console.WriteLine("Please enter a username:");
            var username = Console.ReadLine();
            //Check if username is already taken
            var userExists = context.Users.Any(u => u.Username == username);
            if (userExists)
            {
                Console.WriteLine("Username already exists. Please try again.");
                RegisterUser();
            }
            else
            {
                user.Username = username;
            }
            Console.WriteLine("Please enter a password:");
            var password = Console.ReadLine();
            //ensure password is at least 8 characters
            if (password.Length < 4)
            {
                Console.WriteLine("Password must be at least 4 characters. Please try again.");
                RegisterUser();
            }
            else
            {
                user.Password = password;
            }
            user.Password = password;
            user.Username = username;
            context.Users.Add(user);
            context.SaveChanges();
        }
    }
}

我嘗試以多種不同的方式重新格式化“Using var context”陳述句，我在檔案中看到了這一點。包括將其更改為僅打開和關閉連接。我也嘗試過移動所有連接邏輯的位置。我不確定問題是我試圖從 SelectCharacter 檔案訪問資料庫，還是 Program.cs 檔案中存在問題。

uj5u.com熱心網友回復：

您需要決定什么是靜態方法，什么是實體方法。你有

public SelectCharacter()
{
    _cnstr = Program._configuration["ConnectionStrings:HeroesDB"];
    _optionsBuilder = new DbContextOptionsBuilder<HeroesDBContext>().UseSqlServer(_cnstr);
}

private static void RegisterUser()
{
    using var context = new HeroesDBContext(_optionsBuilder.Options);
    

由于 RegisterUser() 是一個靜態方法，因此沒有 SelectCharacter 實體，并且分配 _optionsBuilder 的 SelectCharacter() 建構式沒有運行。

標籤：C＃sql服务器数据库tsql联系

上一篇：如何用不同的值更新同一列

下一篇：從SQLServer列中提取子字串