Entity framework 添加具有实体框架的控制器失败-DbContext错误

我有一个带有EntityFramework的.Net核心应用程序。 我想添加带有CRUD操作的控制器。 但我犯了这个错误

执行添加迁移时，我没有收到任何错误。它只找到一个DbContext

这些都是我拥有WebApplication8Context的地方

WEBAPPLICATION8CONTEXT.CS

    namespace WebApplication8.Data
{
    public class WebApplication8Context : IdentityDbContext<ApplicationUser>
    {
        public WebApplication8Context(DbContextOptions<WebApplication8Context> options)
            : base(options)
        {
        }
     

        public DbSet<Tasks> Tasks { get; set; }
        public DbSet<TaskGroups> TaskGroups { get; set; }
        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);
            // Customize the ASP.NET Identity model and override the defaults if needed.
            // For example, you can rename the ASP.NET Identity table names and more.
            // Add your customizations after calling base.OnModelCreating(builder);

        }
    }

    [assembly: HostingStartup(typeof(WebApplication8.Areas.Identity.IdentityHostingStartup))]
namespace WebApplication8.Areas.Identity
{
    public class IdentityHostingStartup : IHostingStartup
    {
        public void Configure(IWebHostBuilder builder)
        {
            builder.ConfigureServices((context, services) => {
                services.AddDbContext<WebApplication8Context>(options =>
                    options.UseSqlServer(
                        context.Configuration.GetConnectionString("WebApplication8ContextConnection")));

                services.AddDefaultIdentity<ApplicationUser>(options => options.SignIn.RequireConfirmedAccount = true)
                    .AddEntityFrameworkStores<WebApplication8Context>();
            });
        }
    }
}

搜索我的Web应用程序8ModelSnapshot

    namespace WebApplication8.Migrations
{
    [DbContext(typeof(WebApplication8Context))]
    partial class WebApplication8ContextModelSnapshot : ModelSnapshot
    {
        protected override void BuildModel(ModelBuilder modelBuilder)
        {
#pragma warning disable 612, 618
            modelBuilder
                .HasAnnotation("ProductVersion", "3.1.10")
                .HasAnnotation("Relational:MaxIdentifierLength", 128)
                .HasAnnotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn);

My Startup.cs

    namespace WebApplication8
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllersWithViews();
            services.AddRazorPages();

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                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.UseAuthentication();
            app.UseAuthorization();

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

我可以找到WebApplication8Context的其他地方是我的迁移

---

我做错了什么？

看起来

IdentityHostingStartup

和

Startup

之间存在冲突

虽然我不知道具体原因，但您可以使用以下方法解决：

您可以删除

IdentityHostingStartup

中的代码，然后将其添加到

启动中，如下所示：

    services.AddDbContext<WebApplication8Context>(options =>
            options.UseSqlServer(
                Configuration.GetConnectionString("WebApplication8ContextConnection")));
    services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
            .AddEntityFrameworkStores<WebApplication8Context>();
    services.AddControllersWithViews();
    services.AddRazorPages();

services.AddDbContext（选项=>
options.UseSqlServer(
GetConnectionString（“WebApplication8ContextConnection”）；
services.AddDefaultIdentity（options=>options.SignIn.RequireConfirmedAccount=true）
.AddEntityFrameworkStores（）；
services.AddControllersWithViews（）；
services.AddRazorPages（）；

重新迁移并更新数据库，然后您将成功添加控制器。
将代码添加到启动，而不是identityhostingstartup:）谢谢！
    services.AddDbContext<WebApplication8Context>(options =>
            options.UseSqlServer(
                Configuration.GetConnectionString("WebApplication8ContextConnection")));
    services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
            .AddEntityFrameworkStores<WebApplication8Context>();
    services.AddControllersWithViews();
    services.AddRazorPages();