带有外键的Fluent nHibernate“非null属性引用了null或瞬态值”

Question

I'm trying to do an insert into a database. I have the following two entities:

USER:

public class User
{
    private UserDescription _userDescription;

    public virtual uint Id { get; set; }
    public virtual string Email { get; set; }
    public virtual string Username { get; set; }

    public virtual UserDescription UserDescription
    {
        get { return _userDescription; }
        set { _userDescription = value; }
    }

    public virtual void Add(UserDescription userDescription)
    {
        if (_userDescription != null)
        {
            _userDescription.User = null;
        }
        _userDescription = userDescription;
        _userDescription.User = this;
    }

    public class UserMap : ClassMap<User>
    {
        public UserMap()
        {
            Table("users");

            Id(x => x.Id).GeneratedBy.Identity();
            Map(x => x.Email).Not.Nullable();
            Map(x => x.Username).Not.Nullable();

            HasOne(x => x.UserDescription).Cascade.All().LazyLoad();
        }
    }
}

And USERDESCRIPTION :

public class UserDescription
{
    public virtual uint Id { get; set; }
    public virtual User User { get; set; }
    public virtual uint UserId { get; set; }
    public virtual string Firstname { get; set; }
    public virtual string Lastname { get; set; }

    public class UserDescrptionMap : ClassMap<UserDescription>
    {
        public UserDescrptionMap()
        {
            Table("usersdescription");

            Id(x => x.Id).GeneratedBy.Identity();

            Map(x => x.UserId);
            Map(x => x.Firstname);
            Map(x => x.Lastname);

            HasOne(x => x.User).Constrained().ForeignKey();
        }
    }
}

And my JSON that I pass through looks like the following:

{
   "Email": "Example3@gmail.com",
   "Username": "Something123",
   "UserDescription": {
       "Firstname": "John",
       "Lastname": "Doe"
   }
}

I tried doing an insert into User hoping that it would cascade down and also insert into the child table UserDescription, but that didn't work. So instead I insert into user first then insert into UserDescription (not sure if this is ideal).

Anyway, I get the following error when I try to insert into UserDescription after I successfully insert to User:

not-null property references a null or transient value Users.Entities.UserDescription.User

Any suggestions?

Answer 1

In case anyone's interested, I removed the ".Constrained()" in the UserDescription Mapping and that seemed to work. Although I dont know if that is the best solution!