如何在EF core 5中创建三方关系

// User.cs
public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ICollection<Role> Roles { get; set; }
}

// Role.cs
public class Role
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ICollection<User> Users { get; set; }
}

// UserRole.cs
public class UserRole
{
    public int UserId { get; set; }
    public User User { get; set; }
    public int RoleId { get; set; }
    public Role Role { get; set; }
}

// DbContext.cs
public class MyDbContext : DbContext
{
    public DbSet<User> Users { get; set; }
    public DbSet<Role> Roles { get; set; }
    public DbSet<UserRole> UserRoles { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<UserRole>()
            .HasKey(ur => new { ur.UserId, ur.RoleId });

        modelBuilder.Entity<UserRole>()
            .HasOne(ur => ur.User)
            .WithMany(u => u.Roles)
            .HasForeignKey(ur => ur.UserId);

        modelBuilder.Entity<UserRole>()
            .HasOne(ur => ur.Role)
            .WithMany(r => r.Users)
            .HasForeignKey(ur => ur.RoleId);
    }
}