.NET 6带有实体框架核心的单文件ASP.NET模板

Question

我正在使用 Visual Studio 2022/.NET 6 Razor 页面模板。它使用顶级 C# 10 程序文件。 Program.cs 看起来像这样：

using Microsoft.EntityFrameworkCore;
using Data;
using Services;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddMemoryCache();
builder.Services.AddRazorPages();

var settings = builder.Configuration.Get<AppSettings>();

builder.Services
    .AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

var app = builder.Build();
app.UseHttpsRedirection();
app.UseRouting();
app.MapRazorPages();
app.Run();

我的 DBContext 看起来像这样

public class ApplicationDbContext: DbContext
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options) { }
    internal DbSet<MyModel> MyModels { get; set; }
    protected override void OnModelCreating(ModelBuilder builder){ /* ... */ }
}

当我运行 dotnet ef migrations add InitialMigration -v 时，我收到以下错误：

Finding DbContext classes...
Finding IDesignTimeDbContextFactory implementations...
Finding application service provider in assembly 'Data'...
Finding Microsoft.Extensions.Hosting service provider...
No static method 'CreateHostBuilder(string[])' was found on class 'Program'.
No application service provider was found.
Finding DbContext classes in the project...
Found DbContext 'ApplicationDbContext'.
Microsoft.EntityFrameworkCore.Design.OperationException: Unable to create an object of type 'ApplicationDbContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
 ---> System.InvalidOperationException: Unable to resolve service for type 'Microsoft.EntityFrameworkCore.DbContextOptions`1[Data.DatabaseContext.ApplicationDbContext]' while attempting to activate 'Data.DatabaseContext.ApplicationDbContext'.

Visual Studio Add-Migration 也构建失败，但不提供堆栈跟踪。

提供的链接表明我可以添加 的实现IDesignTimeDbContextFactory 包含一些可能有效的启动代码。

我创建了这个类，但它似乎也没有做任何事情。

public class ApplicationContext: IDesignTimeDbContextFactory<ApplicationDbContext>
{
    ApplicationDbContext IDesignTimeDbContextFactory<SanDiegoContext>.CreateDbContext(string[] args)
    {
        IConfigurationRoot configuration = MyStaticConfigurationBuilder.GetConfig();

        var optionsBuilder = new DbContextOptionsBuilder<ApplicationDbContext>();
        optionsBuilder.UseSqlServer(connectionString: configuration.GetConnectionString("DefaultConnection"));

        return new ApplicationDbContext(optionsBuilder.Options);
    }
}

是否可以在 .NET 6 中使用 EF Core，而无需构建 GetHostBuilder(string[]) 方法和 Startup 类？如果是这样，我做错了什么？

Answer 1

我通过以下步骤使其工作：

1. 重建项目。
2. 确保我在正确的项目中使用 Visual Studio 命令行工具
3. 将 Microsoft.EntityFrameworkCore.Design 安装到我的 Web 项目
4. 确保我的项目使用标准 CTRL-B 自行构建code> 或 dotnet build

然后我的启动看起来像这样：

using Microsoft.EntityFrameworkCore;
using Data;
using Services;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddMemoryCache();
builder.Services.AddRazorPages();

var settings = builder.Configuration.Get<AppSettings>();

builder.Services
    .AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

var app = builder.Build();
app.UseHttpsRedirection();
app.UseRouting();
app.MapRazorPages();
app.Run();

并且迁移尝试照常搭建脚手架