Identity角色管理一（准备工作）

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

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

    //增加用户及用户组服务
    services.AddIdentity<IdentityUser, IdentityRole>(options => options.SignIn.RequireConfirmedAccount = true)
        .AddEntityFrameworkStores<ApplicationDbContext>();
}

private readonly RoleManager<IdentityRole> _roleManager;
private readonly UserManager<IdentityUser> _userManager;

public RoleController(RoleManager<IdentityRole> roleManager, UserManager<IdentityUser> userManager)
{
    _roleManager = roleManager;
    _userManager = userManager;
}