Hi Thomas, I am not familiar with ODMG but I will go to study it. One question needs your help, is it meant that in the mapping file for this DListImpl I do not need to configure the attribute element-class-ref for collection-descriptor tag? Regards, Rice
--- Mahler Thomas <[EMAIL PROTECTED]> wrote: > Hello Rice, > > > > Hi, > > I have been using OJB for some period. I am > taking a > > project left by a partner that uses Hinbernate for > > persistence. So I start studying Hibernate. > Hibernate > > has a mapping function called "any type mapping" > that > > is defined as the follows: > > > > "The <any> mapping element defines a polymorphic > > association to classes from multiple tables. This > type > > of mapping always requires more than one column. > The > > first column holds the type of the associated > entity. > > The remaining columns hold the identifier. It is > > impossible to specify a foreign key constraint for > > this kind of association, so this is most > certainly > > not meant as the usual way of mapping > (polymorphic) > > associations." > > > > This kind of mapping is quite useful when dealing > with > > fields of java.lang.Object or interface. However, > as I > > know, there is no such support in OJB. > > That's not true! > OJB allows to build completely polymorphic mappings. > Just have a look at the > o.a.ojb.odmg.collections.DListImpl class. > It is a list implementation that can hold elements > of arbitrary persistent > classes. > > The trick is that we store serialized Identity > objects as "pointers" to the > actual objects. > If you look at the DListImpl code you will see how > easy it is. > > cheers, > Thomas > > > > I try to study > > the source code of OJB, but am still not able to > > figure out the way to modify it (The xml mapping > > handling code is a little hard to understand, just > > wonder if it is possible to re-write it with Jibx > to > > make it more concise). > > > > Regards, > > Rice > > > > > > __________________________________ > > Do you Yahoo!? > > Exclusive Video Premiere - Britney Spears > > http://launch.yahoo.com/promos/britneyspears/ > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: > [EMAIL PROTECTED] > > For additional commands, e-mail: > [EMAIL PROTECTED] > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: > [EMAIL PROTECTED] > For additional commands, e-mail: > [EMAIL PROTECTED] > __________________________________ Do you Yahoo!? Protect your identity with Yahoo! Mail AddressGuard http://antispam.yahoo.com/whatsnewfree --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
