Asp.net core 设定数据库种子时RoleManager ArgumentNullException

当我运行我的应用程序时，在

ensureedataasync

方法的第一个

if

条件中，抛出一个

ArgumentNullException

，并显示消息“

值不能为null。

”。当它到达这一点时，_roleManager不为空。给定给构造函数的参数也不是null

FletnixUser

是从

IdentityUser

继承的空类，

FletnixRole

是从

IdentityRole

继承的空类

有人知道是什么导致了这个错误吗？我无法找到原因，甚至重建了数据库并将其迁移到identity框架。我试着注释掉所有的角色函数和FletnixSeedData构造函数中的第三个参数，这样它只创建一个用户，这是可行的

我包含了

startup.cs

类，因为该类是调用

FletnixSeedData

类的唯一类

FletnixSeedData.cs

---

您是否检查了

\u roleManager

是否为空？是的，正如我在问题顶部提到的。这就是它的奇怪之处，一切似乎都很好，但它仍然会抛出一个错误。啊，对不起，错过了。角色经理是否具有所有正确的从属关系？您能进入

角色列表同步吗？
public class FletnixSeedData {
    private FletnixContext _context;
    private UserManager<FletnixUser> _userManager;
    private RoleManager<FletnixRole> _roleManager;

    public FletnixSeedData(FletnixContext context, UserManager<FletnixUser> userManager, RoleManager<FletnixRole> roleManager) {
        _context = context;
        _userManager = userManager;
        _roleManager = roleManager;
    }

    public async Task EnsureSeedDataAsync() {
        // If roles and users exist, delete
        if (!await _roleManager.RoleExistsAsync("Customer")) {
            await _roleManager.DeleteAsync(await _roleManager.FindByNameAsync("Customer"));
        }
        if (await _roleManager.FindByNameAsync("Admin") != null) {
            await _roleManager.DeleteAsync(await _roleManager.FindByNameAsync("Admin"));
        }
        if (await _roleManager.FindByNameAsync("FinancialManager") != null) {
            await _roleManager.DeleteAsync(await _roleManager.FindByNameAsync("FinancialManager"));
        }
        if (await _roleManager.FindByNameAsync("CEO") != null) {
            await _roleManager.DeleteAsync(await _roleManager.FindByNameAsync("CEO"));
        }

        if (await _userManager.FindByEmailAsync("myemail@gmail.com") != null) {
            await _userManager.DeleteAsync(await _userManager.FindByEmailAsync("myemail@gmail.com"));
        }


        // Recreate roles and users
        var customerRole = new FletnixRole {
            Name = "Customer"
        };
        var adminRole = new FletnixRole {
            Name = "Admin"
        };
        var financialManagerRole = new FletnixRole {
            Name = "FinancialManager"
        };
        var ceoRole = new FletnixRole {
            Name = "CEO"
        };
        await _roleManager.CreateAsync(customerRole);
        await _roleManager.CreateAsync(adminRole);
        await _roleManager.CreateAsync(financialManagerRole);
        await _roleManager.CreateAsync(ceoRole);

        var newUser = new FletnixUser {
            UserName = "myusername",
            Email = "myemail@gmail.com"
        };
        await _userManager.CreateAsync(newUser, "P@ssw0rd!");
        await _userManager.AddToRoleAsync(newUser, "Customer");
    }
}

    public void ConfigureServices(IServiceCollection services) {
        services.AddMvc();

        services.AddIdentity<FletnixUser, FletnixRole>(config => {
            config.User.RequireUniqueEmail = true;
            config.Password.RequiredLength = 6;
            config.Cookies.ApplicationCookie.LoginPath = "/Auth/Login";
        }).AddEntityFrameworkStores<FletnixContext>();

        services.AddEntityFramework()
            .AddSqlServer()
            .AddDbContext<FletnixContext>();

        services.AddScoped<IFletnixRepository, FletnixRepository>();
        services.AddTransient<FletnixSeedData>();
    }

    public async void Configure(IApplicationBuilder app, FletnixSeedData seeder) {
#if DEBUG
        app.UseDeveloperExceptionPage();
#endif

        app.UseStaticFiles();

        app.UseIdentity();

        app.UseMvc(config => {
            config.MapRoute(
                name: "Default",
                template: "{controller}/{action}/{id?}",
                defaults: new {
                    controller = "Auth", action = "Login"
                }
            );
        });

        await seeder.EnsureSeedDataAsync();
    }