Entity Framework asp net core 关系

Question

我有两个模型： 用户：

using System.ComponentModel.DataAnnotations;

namespace EDiary.Models
{
    public class User
    {
        public int Id { get; set; }
        [Required(AllowEmptyStrings = false, ErrorMessage = "Podaj imię")]
        [MaxLength(25, ErrorMessage = "Imię jest zbyt długie. Max. 25 znaków.")]
        public string FirstName { get; set; }
        [Required(AllowEmptyStrings = false, ErrorMessage = "Podaj nazwisko")]
        [MaxLength(25, ErrorMessage = "Nazwisko jest zbyt długie. Max. 25 znaków.")]
        public string LastName { get; set; }

        [EmailAddress(ErrorMessage = "Podaj prawidłowy adres e-mail")]
        public string Email { get; set; }

        [MinLength(7, ErrorMessage = "Hasło musi składać się z conajmniej 7 znaków")]
        public string Password { get; set; }
        public Class Class { get; set; }
    }
}

和类：

using System.Collections.Generic;

namespace EDiary.Models
{
    public class Class
    {
        public int Id { get; set; }
        public User Educator { get; set; }
        public string ClassName { get; set; }
        public ICollection<User> Users { get; set; }
    }
}

当我进行添加迁移时，我收到一个错误：无法确定由“用户”类型的导航“Class.Educator”表示的关系。手动配置关系，或使用“[NotMapped]”属性或使用“OnModelCreating”中的“EntityTypeBuilder.Ignore”忽略此属性。为什么？

Answer 1

将 ClassId 添加到用户：

public class User
    {
        .....
  public int? ClassId {get; set;}
     [ForeignKey(nameof(ClassId))]
        [InverseProperty("Users")]
        public Class Class { get; set; }
    }

和 EducatorId 到 Class

   public class Class
    {
        public int Id { get; set; }
       public string ClassName { get; set; }

         [ForeignKey("Educator")]
       public int? EducatorId {get; set;}
       public User Educator { get; set; }
      
          [InverseProperty("Class")]
        public ICollection<User> Users { get; set; }
    }