如何使用Entity Framework Code First映射以下关系？
关系 - 作者是主体，ApplicationUser是依赖关系：
ApplicationUser是IdentityUser的派生类 . 作者可以先创建，而不是用户，因此他们是关系的主体 . 每个用户都必须与作者相关联，但作者可能与没有ApplicationUser相关联 . 我试图用流畅的API和注释来做到这一点，但我不能说ApplicationUser的主键是Author的外键 . 非常感谢你！
Models:
public class Author
{
[Key]
public string AuthorId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Email { get; set; }
public List<string> AditionalEmails { get; set; }
public virtual ICollection<PublicationData> Publication { get; set; }
//User is optional.
public virtual ApplicationUser User { get; set; }
}
public partial class ApplicationUser : IdentityUser
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string Affiliation { get; set; }
public string Position { get; set; }
public DateTime CreatedOn { get; set; }
public bool Deleted { get; set; }
public int CountryCode { get; set; }
public virtual Country Country { get; set; }
public virtual ICollection<PublicationData> Publications { get; set; }
public virtual ICollection<Request> Requests { get; set; }
//Author is required
public virtual Author Author { get; set; }
}