ASP.NET Core 2 - 身份 - 自定義角色的DI錯誤

Question

我在Startup.cs中得到了這段代碼：

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

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

在同一個文件中，我還用app.UseAuthentication();替換了service.UseIdentity() app.UseAuthentication(); 正如MS在新版ASP Core 2中所推薦的那樣。

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; }
}

我的自定義Role類：

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

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

    public bool IsDefault { get; set; }
}

運行應用程序時，我得到了一個運行的SeedDatabase幫助器方法：

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

這一切都運行良好，但自從VS 2017更新到最新版本並安裝.NET Core 2.0后，最后一行代碼現在拋出以下異常：

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.

我不確定為什么DI服務管理器不再能夠找到我的ApplicationRole類。 我已經檢查過，我的所有引用都使用了這個類而不是默認的IdentityRole。

有任何想法嗎？

Answer 1

您必須自己創建IServiceScope。

要做到這一點，你必須更換

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
}