Foreign key is null for newly created entity objects

Hi,

I'm creating new objects which have a parent/child (foreign key) relationship to their own types using a nested "for" loop. As I am creating them I am adding them to my unit of work using uow.Add().

At the end of the the nested for loops I am calling uow.SaveChanges(). The objects are being created in the database but their foreign key column is NULL.

Can anyone explain how I can get around this so the foreign key column is not set to null? I am using "KeyTable" for identity generation. When I'm debugging I can see that the entitystate = new and Id = 0, but I was under the impression that using "KeyTable" would acquire a unique key before the object was commit to the db. Here's my code:

PhysicalLocation Lektriever;
var EL_Context = new LightSpeedContext("EnterpriseLibrary");
EL_Context.IdentityMethod = IdentityMethod.KeyTable;
EL_Context.ConnectionString = ConfigurationManager.ConnectionStrings["EnterpriseLibraryDB"].ToString();
using (var uow = EL_Context.CreateUnitOfWork())
{
  Lektriever = uow.FindById<PhysicalLocation>(4);
  for (int ShelfCount = 1; ShelfCount <= 33; ShelfCount++)
  {
    PhysicalLocation Shelf = new PhysicalLocation(
      ShelfCount.ToString("0#"), 
      "Shelf " + ShelfCount.ToString("0#") + " in Lektriever", 
      Lektriever);
    uow.Add(Shelf);
    for (int DrawerCount = 1; DrawerCount <= 14; DrawerCount++)
    {
      PhysicalLocation Drawer = new PhysicalLocation(
        DrawerCount.ToString("0#"), 
        "Drawer " + DrawerCount.ToString("0#") + " of shelf " + ShelfCount.ToString("0#"), 
        Shelf);
      uow.Add(Drawer);
      for (int ColCount = 1; ColCount <= 3; ColCount++)
      {
        char Name = ColCount == 1 ? 'A' : ColCount == 2 ? 'B' : 'C';

        for (int RowCount = 1; RowCount <= 7; RowCount++)
        {
          PhysicalLocation Row = new PhysicalLocation(
            Name + RowCount.ToString(), 
            "Bottle location " + Name + RowCount.ToString() + " of Drawer " + Drawer, 
            Drawer);
          uow.Add(Row);
        }
      }
    }
  }
  uow.SaveChanges();
}

And here's my object PhysicalLocation:

[Table("PhysicalLocations")]
public class PhysicalLocation : Entity<int> {
private PhysicalLocation _ParentLocation;
private string _Name;
private string _Description;
public string Name {
get { return _Name; }
set { Set(ref _Name, value); }
}
public string Description {
get { return _Description; }
set { Set(ref _Description, value); }
}
public PhysicalLocation ParentLocation {
get { return _ParentLocation; }
set { Set(ref _ParentLocation, value); }
}
}

Any help would be greatly appreciated. Thanks in advance.

It looks like you don't have a foreign key field for the ParentLocation association, so the ParentLocationId column isn't getting mapped and therefore isn't getting saved.  Add the following members to the PhysicalLocation class:

  private int? _parentLocationId;

  public int? ParentLocationId
  {
    get { return _parentLocationId; }
    set { Set(ref _parentLocationId, value); }
  }

LightSpeed will automatically wire this up to the ParentLocation association based on the naming convention.  Note that the field must be nullable.

Regarding KeyTable: that is correct.  In fact, KeyTable will assign an ID to the entity as soon as it is added to a unit of work.

Thanks Ivan,

Right after I posted my code I realized I did not have any relationships defined. So I added the following code and got it working like a charm! I wanted to post a reply to my own message but I guess my post had not yet been approved because I did not see the "reply" button.

#region Relationships

[ReverseAssociation("ChildLocations")]
public EntityHolder<PhysicalLocation> _ParentLocation = new EntityHolder<PhysicalLocation>();
public PhysicalLocation ParentLocation
{
	get { return Get(_ParentLocation); }
	set { Set(_ParentLocation, value); }
}
[Column("ParentLocation")] private int? _ParentLocationID;
public int? ParentLocationId
{
	get { return _ParentLocationID; }
	set { Set(ref _ParentLocationID, value); }
}
public readonly EntityCollection<PhysicalLocation> _childLocations = new EntityCollection<PhysicalLocation>();
public EntityCollection<PhysicalLocation> ChildLocations
{
	get { return Get(_childLocations); }
}
#endregion

I also did some quick test between using the KeyTable identity generation strategy and using letting the DB create the keys.. the difference is performance is truly stunning.

I think I'd originally left out the code above because I thought LightSpeed might be able to figure out on its own that the object has relationships on itself. Not that it's a big issue but would it be possible in the future to have this wiring up fully automated? Thanks.

[quote user="SR8"]I think I'd originally left out the code above because I thought LightSpeed might be able to figure out on its own that the object has relationships on itself. Not that it's a big issue but would it be possible in the future to have this wiring up fully automated? Thanks.[/quote]

This probably won't be possible for hand-coded entities, but it is handled for you if you use the designer.