虽然没有错误，但无法更新多个表

Question

我有以下父类，它有多个子类。我已成功创建并从SQL数据库中检索数据。现在我想使用FormCollection更新记录。

public class UserDetailContext : DbContext
{
    public UserDetailContext()
        : base("DefaultConnection")
    {
    }

    public DbSet<UserDetails> UserDetails { get; set; }
    public DbSet<PersonalDetails> PersonalDetails { get; set; }
    public DbSet<HoroscopeDetails> HoroscopeDetails { get; set; }
    public DbSet<Expectations> Expectations { get; set; }
    public DbSet<FamilyDetails> FamilyDetails { get; set; }
    public DbSet<AddressDetails> AddressDetails { get; set; }
    public DbSet<EducationalDetails> EducationalDetails { get; set; }
}    

public class UserDetails
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int UserId { get; set; }
    public List <PersonalDetails>  PdetailsList { get; set; }
    public List<HoroscopeDetails> HDetailsList { get; set; }
    public List<EducationalDetails> EDetailsList { get; set; }

    public List<AddressDetails> AdddetailsList { get; set; }
    public List<FamilyDetails> FDetailsList { get; set; }
    public List<Expectations> ExpDetailsList { get; set; }

    public PersonalDetails Pdetails { get; set; }
    public HoroscopeDetails  HDetails { get; set; }
    public EducationalDetails  EDetails { get; set; }
    public AddressDetails Adddetails { get; set; }
    public FamilyDetails FDetails { get; set; }
    public Expectations ExpDetails { get; set; }
    public UserDetails()
    {
        Pdetails = new PersonalDetails();
        HDetails = new HoroscopeDetails();
        EDetails = new EducationalDetails();

        Adddetails = new AddressDetails();
        FDetails = new FamilyDetails();
        ExpDetails = new Expectations();
    }   
}

public class PersonalDetails
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Column(Order = 0)]
    public int PersonalID { get; set; }

    public int UserId { get; set; }

    public string RegID { get; set; }

    public string FirstName { get; set; }
    public string MidName { get; set; }

    public string LastName { get; set; }


}

public class HoroscopeDetails
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ID { get; set; }

    public string Rashi { get; set; }
    public int PersonalID { get; set; }
    [ForeignKey("PersonalID")]
    public virtual PersonalDetails Product { get; set; }
}

public class EducationalDetails
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Column(Order = 0)]
    public int EduID { get; set; }
    public string EducationDetails { get; set; }
    public string Education { get; set; }
    public int PersonalID { get; set; }
    [ForeignKey("PersonalID")]
    public virtual PersonalDetails Product { get; set; }
}

public class AddressDetails
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int AddId { get; set; }               

    public int PersonalID { get; set; }
    [ForeignKey("PersonalID")]
    public virtual PersonalDetails Product { get; set; }
}

public class FamilyDetails
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int FId { get; set; }


    public int PersonalID { get; set; }
    [ForeignKey("PersonalID")]
    public virtual PersonalDetails Product { get; set; }
}

public class Expectations
{           
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ExpId { get; set; }
    public int PersonalID { get; set; }
    [ForeignKey("PersonalID")]
    public virtual PersonalDetails Product { get; set; }
}

现在来自控制器我想更新记录

public void UpdateRecord(FormCollection coll)
{      
    int id = Convert.ToInt32(Session["UserId"]);
    UserDetails obj = db.UserDetails.FirstOrDefault(s => s.UserId.Equals(id));
    obj.Pdetails.FirstName = "xxxx";
    obj.Pdetails.LastName = "xxxx";
    obj.UserId = Convert.ToInt32(Session["UserId"]);
    db.Entry(obj).State = EntityState.Modified;
    int result = db.SaveChanges();
}

它不会给出任何错误，但也不会更新任何记录 obj对象还包含以下代码的空值：

UserDetails obj = db.UserDetails.FirstOrDefault(s => s.UserId.Equals(id));