[odb-users] ODB polymorphic inheritence problem

[Alexander Konin]

Hi,
I am upgrading from ODB 1.8 to ODB 2.2. And there is problem with polymorphic inheritance. Consider the following hierarchy:
Item <- Parent <- Segment. Item contains pointer to Parent, and Parent has list of contained Items, but concreate Parent descendants declare this list (or lists). So, we have one-to-many relation, and I use inversion on "many" side:

==== File Item.h

class Parent;

// Root class of some subsystem, has reference (parent_) to parent class

#pragma db object polymorphic table("Items")
class Item
{
  private:
     #pragma db id auto
     int id_;

     #pragma db null
     Parent* parent_;
...
};

#ifdef ODB_COMPILER
     #include "Parent.h"
#endif


==== File Parent.h

// Class that designates parent node

#pragma db object table("Parents")
class Parent : public Item
{
   // This class has no members, but descendants have lists of parented items
   ...
};


==== File Segment.h

// A class that is Parent. Segment contains other segments as its children.

#pragma db object table("Segments")
class Segment : public Parent, public Segmentable
{
  private:
     #pragma db value_not_null inverse(parent_)
     QList<Segment*> segments_;
    ...
};


The problem is that ODB generates incorrect SQL instructions for loading Segment::segments_:

==== File Segment-odb.cxx:

const char access::object_traits_impl< ::Database::Segment, id_pgsql >::segments_traits::
select_statement[] =
"SELECT "
"\"Segments\".\"id\""
" FROM \"Segments\""
" WHERE \"Segments\".\"parent\"=$1";

"parent" field is contained in "Items" table (we have Item::parent_), not "Segments" table!

How can I solve the problem, or there is not possible?


Thanks in advance,
Alexander Konin