如何使用Asp.net核心标识的UserId和RoleId将用户添加到角色

// 配置身份验证和授权
services.AddIdentity<IdentityUser, IdentityRole>()
    .AddEntityFrameworkStores<ApplicationDbContext>();

// 创建角色
var roleManager = serviceProvider.GetRequiredService<RoleManager<IdentityRole>>();
var roleName = "Admin";
var roleExists = await roleManager.RoleExistsAsync(roleName);
if (!roleExists)
{
    await roleManager.CreateAsync(new IdentityRole(roleName));
}

// 创建用户
var userManager = serviceProvider.GetRequiredService<UserManager<IdentityUser>>();
var userName = "user@example.com";
var password = "password";
var userExists = await userManager.FindByNameAsync(userName);
if (userExists == null)
{
    var user = new IdentityUser { UserName = userName, Email = userName };
    await userManager.CreateAsync(user, password);
}

// 将用户添加到角色
var userToAdd = await userManager.FindByNameAsync(userName);
await userManager.AddToRoleAsync(userToAdd, roleName);