如何在ASP.NET Core5中的IdentityUser和IdentityRole之间使用隐式多对多

public class UserRoles
{
    public string UserId { get; set; }
    public IdentityUser User { get; set; }

    public string RoleId { get; set; }
    public IdentityRole Role { get; set; }
}

public class ApplicationDbContext : IdentityDbContext
{
    public DbSet<UserRoles> UserRoles { get; set; }
    
    // Other DbSet declarations
    
    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);
        
        // Configure the many-to-many relationship
        builder.Entity<UserRoles>()
            .HasKey(ur => new { ur.UserId, ur.RoleId });

        builder.Entity<UserRoles>()
            .HasOne(ur => ur.User)
            .WithMany(u => u.UserRoles)
            .HasForeignKey(ur => ur.UserId);

        builder.Entity<UserRoles>()
            .HasOne(ur => ur.Role)
            .WithMany(r => r.UserRoles)
            .HasForeignKey(ur => ur.RoleId);
    }
}

public class IdentityUser : IUser
{
    // Other properties

    public virtual ICollection<UserRoles> UserRoles { get; set; }
}

public class IdentityRole : IRole
{
    // Other properties

    public virtual ICollection<UserRoles> UserRoles { get; set; }
}

public class UserController : Controller
{
    private readonly UserManager<IdentityUser> _userManager;
    private readonly RoleManager<IdentityRole> _roleManager;

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

    public async Task<IActionResult> AddUserRole(string userId, string roleId)
    {
        var user = await _userManager.FindByIdAsync(userId);
        var role = await _roleManager.FindByIdAsync(roleId);

        if (user != null && role != null)
        {
            await _userManager.AddToRoleAsync(user, role.Name);
            return Ok();
        }

        return NotFound();
    }
}