当我试图在我的用户之间创建reation时，我遇到了一个问题。一个用户可以是另一个用户的营养师，所以我有这样的结构：

public class ApplicationUser : IdentityUser
{
        [ForeignKey("MenteeId")]
        public virtual ICollection<MenteesDieticians> Dieticians { get; set; }

        [ForeignKey("DieticianId")]
        public virtual ICollection<MenteesDieticians> DieticianMentees { get; set; }
}

public class MenteesDieticians
{
        [Key]
        public int MenteesDieticiansId { get; set; }

        [Required]
        [ForeignKey("Mentee")]
        public string MenteeId { get; set; }

        [ForeignKey("MenteeId")]
        public virtual ApplicationUser Mentee { get; set; }

        [Required]
        [ForeignKey("Dietician")]
        public string DieticianId { get; set; }

        [ForeignKey("DieticianId")]
        public virtual ApplicationUser Dietician { get; set; }
}

在我的DbContext类中，我还定义了关系：

protected override void OnModelCreating(ModelBuilder builder)
{
        base.OnModelCreating(builder);

        builder.Entity<ApplicationUser>()
            .HasMany(x => x.DieticianMentees)
            .WithOne()
            .HasForeignKey(x => x.DieticianId);
        builder.Entity<ApplicationUser>()
            .HasMany(x => x.Dieticians)
            .WithOne()
            .HasForeignKey(x => x.MenteeId);

        builder.Entity<MenteesDieticians>()
            .HasOne(x => x.Mentee)
            .WithOne()
            .HasForeignKey<MenteesDieticians>(t => t.MenteeId);
        builder.Entity<MenteesDieticians>()
            .HasOne(x => x.Dietician)
            .WithOne()
            .HasForeignKey<MenteesDieticians>(t => t.DieticianId);
}

最后，我的迁移代码看起来是这样的：

    migrationBuilder.CreateTable(
        name: "MenteesDieticians",
        columns: table => new
        {
            MenteesDieticiansId = table.Column<int>(nullable: false)
                .Annotation("MySQL:ValueGenerationStrategy", MySQLValueGenerationStrategy.IdentityColumn),
            MenteeId = table.Column<string>(nullable: false),
            DieticianId = table.Column<string>(nullable: false),
            ApplicationUserId = table.Column<string>(nullable: true),
            ApplicationUserId1 = table.Column<string>(nullable: true)
        },

为什么我有这些ApplicationUserId和ApplicationUserId1列？怎么解决？

你觉得这样定义那些关系怎么样？老实说，我需要用户只有一个营养师，但我没有找到实现它的方法。