Re: [Objectbridge-developers] optional relationships

[Dirk O. <di...@xa...>]

Joel Cordonnier wrote:
> 
> > 1) extend the mapping to let the user specify which
> > value object he
> > wants to have assigned for individual attributes. So
> > there would be a
> > <field.valueType/> in addition <field.name/> node in
> > the mapping XML
> > file. This would allow for e.g. Integer values to be
> > passed. To make
> > this work with reflection, JdbcAccess should use a
> > set method if that's
> > available (could be found out using reflection)
> 
> ok ! And what bring this solution ? to assign a given
> value, when you can the type ??

It's all about distinguishing a NULL value that comes from the database
from an (int)0. The two *are* different and you have to make sure that
your app can see which case is which. Using just int's you cannot
distinguish. Using java.lang.Integer gets you further:

int foo = 0;		// is that NULL or really zero

Integer foo = null;		// this really means NULL
Integer foo = new Integer(0);	// this is the Integer value zero.

> I think that the second solution (eg. implement the
> interface) is better.

Does anybody know what other O/R mapping frameworks do? I have some
working knowledge with Apple's Enterprise Objects Framework, they call a
method named unableToTakeNullForKey(String key) on the instance that's
about to have a NULL value assigned.

-dirk