Interestingly, this just came up over in EclipseLink land: http://wiki.eclipse.org/EclipseLink/Examples/JPA/Dynamic
Best, Laird On Wed, May 12, 2010 at 9:36 AM, Kevin Sutter [via OpenJPA] < [email protected]<ml-node%[email protected]> > wrote: > Hi Christopher, > Hmmm... Interesting idea, but is this dynamic mapping really practical? > It > sounds like you are looking for the means to dynamically create or change > the mappings defined by your Entity and your database Schema. The > attribute > types in your Entity definitions will need to match (or at least easily > convert to) the types in your database Schema. Since most customer > database > schemas are fairly static, I don't quite see the need for dynamic mappings. > > > Maybe I need another cup of coffee this morning, but I'd still be > interested > in hearing a specific, real-world use case where the mappings between your > Entity and Schema need to be dynamic. > > Thanks, > Kevin > > On Tue, May 11, 2010 at 11:33 AM, Christopher Gardner < > [hidden email] <http://user/SendEmail.jtp?type=node&node=5041111&i=0>> > wrote: > > > Kevin, > > > > The only use case I can think of is the obvious one: a mapping system > > more expressive and typesafe than xml, while allowing for refactoring > and > > clutter-free entity code. However--and this is just coming off the top > of > > my head as I'm writing--I wonder if there might be needs to compute > > mappings > > based on dynamic criteria rather than be bound to compiled annotations or > > > static xml (of course, I can't think of what those needs are at the > > moment). > > > > On Tue, May 11, 2010 at 12:21 PM, Kevin Sutter <[hidden > > email]<http://user/SendEmail.jtp?type=node&node=5041111&i=1>> > wrote: > > > > > Hi Christopher, > > > Now I see what you meant by a "fluent API"... To be honest, my > viewpoint > > > of > > > this API was to allow for an alternate means of configuring Hibernate, > > > other > > > than just using XML. Classic Hibernate only supported configuration > > > through > > > XML, so this fluentHibernate allowed for a programming-based mechanism > > for > > > configuration. On the surface, it seems like this would be more > > difficult > > > to use than just using annotations. > > > > > > Can you provide any use cases in the JPA sense that would describe how > > this > > > type of configuration API would be helpful? > > > > > > On a similar vein, we are considering an API to help with configuration > > > of > > > the persistence unit. Since the persistence unit is defined by the > > > persistence.xml only, allowing some alternate means via an API would be > > > > welcome. > > > > > > Kevin > > > > > > On Tue, May 11, 2010 at 10:27 AM, Christopher Gardner < > > > [hidden email] <http://user/SendEmail.jtp?type=node&node=5041111&i=2>> > wrote: > > > > > > > Thanks. I'm in the former camp, i.e., a legacy database. I'm aware > of > > > the > > > > xml alternative. Though I'm no DotNet developer, I read about an > > Fluent > > > > NHibernate, which allows you to create a object to store mapping in > > code. > > > > > > > > http://wiki.fluentnhibernate.org/Getting_started > > > > > > > > <http://wiki.fluentnhibernate.org/Getting_started>Maybe such an API > > > isn't > > > > appropriate for a spec, but it would be an interesting alternative to > > > > both > > > > annotations and xml for JPA. > > > > > > > > On Tue, May 11, 2010 at 11:21 AM, Kevin Sutter <[hidden > > > > email]<http://user/SendEmail.jtp?type=node&node=5041111&i=3>> > > > > wrote: > > > > > > > > > Hi Christopher, > > > > > You're right, annotations can be verbose. But, they don't have to > > be. > > > > It > > > > > all depends on whether your application can live with the default > > > > > processing > > > > > defined by the spec. We tried to pick the most common default > values > > > for > > > > > the various annotation elements. If your application can live with > > > the > > > > > default processing, then all that is really necessary is the > @Entity > > > and > > > > > @Id > > > > > annotations. But, most legacy applications and schemas can not > live > > > with > > > > > the default settings, thus the annotations can become verbose. > > > > Flexibility > > > > > can be a killer... But, then we'd be crucified if we didn't allow > > for > > > > the > > > > > flexibility... :-) > > > > > > > > > > The annotations can also be overridden via orm.xml declarations. > > This > > > > > would > > > > > keep your base code more readable, while putting the detailed gorp > > into > > > > the > > > > > xml file(s). Maybe this would be more suitable for your > environment. > > > > > > > > > > Not sure what you mean by "fluent API". Any specific examples to > > help > > > > with > > > > > this discussion? > > > > > > > > > > Thanks, > > > > > Kevin > > > > > > > > > > On Tue, May 11, 2010 at 10:10 AM, Christopher Gardner < > > > > > [hidden email]<http://user/SendEmail.jtp?type=node&node=5041111&i=4>> > wrote: > > > > > > > > > > > Vis-a-vis all JPA specs, streamlining annotations would be nice. > > The > > > > > > annotations can be verbose. Maybe a fluent API would be in > order. > > > > > > > > > > > > On Tue, May 11, 2010 at 10:46 AM, Kevin Sutter <[hidden > > > > > > email]<http://user/SendEmail.jtp?type=node&node=5041111&i=5> > > > > > > > > wrote: > > > > > > > > > > > > > Hi Chris, > > > > > > > Sorry to hear that you are frustrated with JPA 2.0. Can you > > > > elaborate? > > > > > > > The > > > > > > > JPA Expert Group is currently soliciting feedback for the next > > > > revision > > > > > > of > > > > > > > the JPA spec (2.x or 3.0). Here's the e-mail address for this > > > > > > > correspondence [1]. But, if there are distinct improvements > that > > > are > > > > > you > > > > > > > looking for, maybe they could be entertained by the OpenJPA > > > community > > > > > > > first. Bugs and/or Features can be entered into our JIRA > system > > > [2] > > > > > for > > > > > > > future consideration. Of course, community involvement can > help > > > > speed > > > > > up > > > > > > > this process. > > > > > > > > > > > > > > Thanks for the input, > > > > > > > Kevin > > > > > > > > > > > > > > [1] [hidden > > > > > > > email]<http://user/SendEmail.jtp?type=node&node=5041111&i=6> > > > > > > > [2] https://issues.apache.org/jira/browse/OPENJPA > > > > > > > > > > > > > > On Tue, May 11, 2010 at 9:12 AM, C N Davies <[hidden > > > > > > > email]<http://user/SendEmail.jtp?type=node&node=5041111&i=7>> > > > > > wrote: > > > > > > > > > > > > > > > I'm so frustrated by JPA 2.0 but can't seem to find an JSR > for > > > JPA > > > > 3 > > > > > or > > > > > > > > anything. Can anyone point me it? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks J > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Chris > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > ------------------------------ > View message @ > http://openjpa.208410.n2.nabble.com/JPA-3-0-tp5036154p5041111.html > To start a new topic under OpenJPA Users, email > [email protected]<ml-node%[email protected]> > To unsubscribe from OpenJPA Users, click here< (link removed) =>. > > > -- View this message in context: http://openjpa.208410.n2.nabble.com/JPA-3-0-tp5036154p5041124.html Sent from the OpenJPA Users mailing list archive at Nabble.com.
