ASP.NET Core 2 - 身份 - 自定义角色的DI错误

Question

我在Startup.cs中得到了这段代码：

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

        services.AddIdentity<ApplicationUser, ApplicationRole>()
            .AddEntityFrameworkStores<ApplicationDbContext>()
            .AddDefaultTokenProviders();

在同一个文件中，我还在新版本的ASP Core 2中用MS推荐的service.UseIdentity()替换了app.UseAuthentication();。

我的Db背景：

 public class ApplicationDbContext : IdentityDbContext<ApplicationUser, ApplicationRole, string>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }

    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);
    }


    //public DbSet<ApplicationUser> ApplicationUser { get; set; }

    //public DbSet<ApplicationRole> ApplicationRole { get; set; }
}

我的自定义Role类：

 public class ApplicationRole : IdentityRole
{
    public ApplicationRole() : base() { }

    public ApplicationRole(string roleName) : base(roleName) { }

    public bool IsDefault { get; set; }
}

运行应用程序时，我得到了一个运行的SeedDatabase帮助器方法：

var roleManager = serviceProvider.GetService<RoleManager<ApplicationRole>>();

这一切都运行良好，但自从将VS 2017更新到最新版本并安装.NET Core 2.0后，最后一行代码现在抛出以下异常：

System.AggregateException occurred
HResult=0x80131500
Message=One or more errors occurred. (Cannot resolve scoped service 'Microsoft.AspNetCore.Identity.RoleManager`1[CspLicensingPortal.Models.ApplicationRole]' from root provider.)
Source=<Cannot evaluate the exception source>
StackTrace:
at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
at System.Threading.Tasks.Task.Wait()
at CspLicensingPortal.Startup.Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) in D:\gsandorx\Documents\Visual Studio 2017\Projects\CspLicensingPortal\CspLicensingPortal\Startup.cs:line 275

Inner Exception 1:
InvalidOperationException: Cannot resolve scoped service 'Microsoft.AspNetCore.Identity.RoleManager`1[MyApplication.Models.ApplicationRole]' from root provider.

我不确定为什么DI服务管理器不再能够找到我的ApplicationRole类。我已经检查过，我的所有引用都使用了这个类而不是默认的IdentityRole。

有任何想法吗？

Answer 1

您必须自己创建IServiceScope。

要做到这一点，你必须更换

var roleManager = serviceProvider.GetService<RoleManager<ApplicationRole>>();

同

using (IServiceScope scope = app.ApplicationServices.CreateScope()) {
    RoleManager<IdentityRole> roleManager = scope.ServiceProvider.GetRequiredService<RoleManager<IdentityRole>>();

    // Seed database code goes here
}