[ojb-users] Mapping Inheritance hierarchy

[Govindarajan S (Gover) <gov...@az...>]

Hi,
I have a doubt regarding the mapping of an inheritance hierarchy.

The first approach of mapping the entire inheritance hierarchy seems to
be fine. Also i understand that OBJ supports 'Concrete Table inheritance
mapping' ie mapping all concrete tables.

My question is whether i can implement the 'Class table inheritance
mapping' ie mapping all classes (including abstract classes)to
individual tables. If yes how?

One doubt i had is how to link a derived class 'D' with its parent class
'A'. Assume FootBall player class is inherited from Player and that
player has an unique playerId. Now when u map the FootBall player to its
corresponding table how will you write/read values from the Player table
?

 One of the white-papers suggested using foreignkey reference to the
parent table. I understand that to implement this i would need to do a
1-1 mapping between the derived classes and the base class. But the way
OBJ does 1-1 mapping u need to have a reference to the Base class in the
derived class instance or vice-versa. This is where it hurts me, becoz
what is the point in referring to the base class explicitly in a derived
class? or iam missing some very obivious point here?

I dont think i can use an external table for doing a 1-1 mapping between
the Player table and Football player?

gover