DataMapper solve saves deep relations in session?

[eluser]titoneo[/eluser]
Any suggestion? I have being seen Doctrine and does what I want.

But I can't store my models objects, that extends Doctrine_Record, in session (using Session codeigniter class) because they have a large size when serializing.

In this case, I have to create aditional 'transfer objects' to store them in session.

Another option is to use native sessions..

Any elegant solution?

Thanks