Csharp 无法解析数据库上下文的服务

为了获得ASP.NET Core MVC网站，在崩溃后，我再次按照this thread的指示进行操作.

我安装了Visual Studio扩展，插入了四个Entity Framework Core引用，在用正确的值替换DbContext的名称之后，我根据this thread输入了dotnet ef database update等等.

我读了答案，当有错误时，白色背景.

(为了验证此步骤是否正确执行，我需要在解决方案中搜索什么内容？)

现在，我在下面的内容中处理"无法解决dbContext上的服务"错误，考虑到我所做的不同try 的次数，在我能够编写简明综合之前，有人可以更准确地指出这个错误似乎会有所帮助.在那之后，我将负责将连接字符串存储在一个更机密的地方，但首先获取网页上的数据可能是一个有趣的步骤.

如您所知，我可以创建一个订单控制器，但是当我试图显示它的索引页面时，我得到了错误

"InvalidOperationException:try 激活‘MVCumul_01.Controllers.OrdersController’时，无法解析类型为‘MVCumul_01.Models.NorthwinContext’的服务. Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ThrowHelperUnableToResolveService(Type类型，必填类型By)

我验证了连接字符串(该错误出现在上一次try 中).在Windows11版本23H2(OS Build 22631.3296)上，数据正确显示在Visual Studio2022社区中的服务器资源管理器中，和/或SSMS 19.1中

我首先忘记了在ConfigureServices中声明AddDbContextFactory，然后声明它和NorthwindContext都是singleton，然后都是作用域(这应该都有效)，然后混合(这不应该工作，或者可能我混淆了，但不是...浪费旅行).

下面是代码:

Startup.cs:

using Microsoft.EntityFrameworkCore;
using MVCcumul_01.Models;

namespace MVCcumul_01
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            var connectionString = @"Data Source=.\\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True;Encrypt=True;TrustServer²Certificate=True";

            services.AddDbContext<NorthwindContext>(options => options.UseSqlServer(connectionString),
                ServiceLifetime.Singleton);

            services.AddDbContextFactory<NorthwindContext>(
               options => options.UseSqlServer(),
                lifetime: ServiceLifetime.Singleton);
        }

        public void Configure()
        {
        }
    }
}

Program.cs:

using Microsoft.AspNetCore.Hosting;
using MVCcumul_01;

// EF Core uses this method at design time to access the DbContext
static IHostBuilder CreateHostBuilder(string[] args)
    => Host.CreateDefaultBuilder(args)
.ConfigureWebHostDefaults(
            webBuilder => webBuilder.UseStartup<Startup>()); 

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllersWithViews();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

app.Run();

ApplicationDbContextFactory.cs:

using Microsoft.EntityFrameworkCore.Design;
using Microsoft.EntityFrameworkCore;

namespace MVCcumul_01.Models
{
    internal class ApplicationDbContextFactory : IDesignTimeDbContextFactory<NorthwindContext>
    {
        NorthwindContext IDesignTimeDbContextFactory<NorthwindContext>.CreateDbContext(string[] args)
        {
            IConfigurationRoot configuration = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json")
                .Build();

            var builder = new DbContextOptionsBuilder<NorthwindContext>();
            var connectionString = configuration.GetConnectionString("DefaultConnection");

            builder.UseSqlServer(connectionString);

            return new NorthwindContext(builder.Options);
        }
    }
}

appsettings.json:

{
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft.AspNetCore": "Warning"
        }
    },
    "AllowedHosts": "*",
    "ConnectionStrings": {
        "MVCcumul_01Context1": "Server=(localdb)\\mssqllocaldb;Database=MVCcumul_01Context-bfca8e78-d989-4ba3-a265-435e16ece2bb;Trusted_Connection=True;MultipleActiveResultSets=true",
        "MVCcumul_01Context": "Data Source=.\\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True;Encrypt=True;Trust Server Certificate=True"
    }
}