如何首先通过数据库实现ASP.NET核心标识

services.AddIdentity<IdentityUser, IdentityRole>()
    .AddEntityFrameworkStores<ApplicationDbContext>()
    .AddDefaultTokenProviders();

public class ApplicationUser : IdentityUser
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class AccountController : Controller
{
    private readonly UserManager<ApplicationUser> _userManager;
    private readonly SignInManager<ApplicationUser> _signInManager;

    public AccountController(UserManager<ApplicationUser> userManager, SignInManager<ApplicationUser> signInManager)
    {
        _userManager = userManager;
        _signInManager = signInManager;
    }

    // 注册
    [HttpPost]
    public async Task<IActionResult> Register(RegisterViewModel model)
    {
        if (ModelState.IsValid)
        {
            var user = new ApplicationUser { UserName = model.Email, Email = model.Email };
            var result = await _userManager.CreateAsync(user, model.Password);
            if (result.Succeeded)
            {
                // 注册成功逻辑
            }
        }

        // 注册失败逻辑
    }

    // 登录
    [HttpPost]
    public async Task<IActionResult> Login(LoginViewModel model)
    {
        if (ModelState.IsValid)
        {
            var result = await _signInManager.PasswordSignInAsync(model.Email, model.Password, model.RememberMe, lockoutOnFailure: false);
            if (result.Succeeded)
            {
                // 登录成功逻辑
            }
        }

        // 登录失败逻辑
    }
}

[Authorize(Roles = "Admin")]
public class AdminController : Controller
{
    // 管理员功能
}

public class RoleController : Controller
{
    private readonly RoleManager<IdentityRole> _roleManager;

    public RoleController(RoleManager<IdentityRole> roleManager)
    {
        _roleManager = roleManager;
    }

    public async Task<IActionResult> CreateRole(string roleName)
    {
        if (!await _roleManager.RoleExistsAsync(roleName))
        {
            var role = new IdentityRole { Name = roleName };
            await _roleManager.CreateAsync(role);
        }

        // 角色创建逻辑
    }
}