AW: [odb-users] Object Model based on Interfaces

Lichtenberger, Christian christian.lichtenberger at
Thu Jun 12 10:23:16 EDT 2014

I think this should be relatively easy to implement in ODB.

All you need is a own object_traits:
template <>
  class WBE_REPOSITORY_EXPORT access::object_traits< ::IDerived > :
    public access::object_traits< ::Derived >

And a cast in the object_traits_impl, which depends on the pointer type

First one I have tried, but second is not possible without modifying generated code.

One open question is how get the odb compiler the necessary information?

#pragma db object
#pragma db interface IDerived
Class Derived : Base, IDerived

#pragma db interface
Class IDerived


-----Ursprüngliche Nachricht-----
Von: Boris Kolpackov [mailto:boris at] 
Gesendet: Donnerstag, 12. Juni 2014 12:02
An: Lichtenberger, Christian
Cc: odb-users at
Betreff: Re: [odb-users] Object Model based on Interfaces

Hi Christian,

Lichtenberger, Christian <christian.lichtenberger at> writes:

> #pragma db object polymorphic
> class Base
> {
>   //some base functionality
> }
> class IDerived
> {
>   //define pure virtual functions
> }
> #pragma db object
> class Derived : public Base, public IDerived {
>   //implements virtual functions
> }
> How can I archive that following is possible:
> main()
> {
>   QSharedPointer<odb::database> db;
>   IDerived derived = new Derived;
>   db->persist<IDerived>(derived);
> }

To persist via IDerived you would have to make it a persistent object. But ODB does not support multiple inheritance. So the only way is to simplify this somehow into a single inheritance chain (e.g., derive Base from IDerived or the other way around).


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