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From "C N Davies" <...@cndavies.com>
Subject RE: equals, hashcode, toString, etc, and field access
Date Mon, 31 May 2010 05:22:18 GMT

EntityManagerFactory.


-----Original Message-----
From: Trenton D. Adams [mailto:trent@trentonadams.ca] 
Sent: Monday, 31 May 2010 2:19 PM
To: users@openjpa.apache.org; cnd@cndavies.com
Subject: Re: equals, hashcode, toString, etc, and field access

EMF?
ElectorMagnetic Field?
English Musical Festival?
Educational Media Foundation?
Energy Modeling Forum?
Eclipse Modeling Framework?

Google wasn't helpful. lol

----- "C N Davies" <cnd@cndavies.com> wrote:

> From: "C N Davies" <cnd@cndavies.com>
> To: users@openjpa.apache.org
> Sent: Sunday, May 30, 2010 7:14:44 PM GMT -07:00 US/Canada Mountain
> Subject: RE: equals, hashcode, toString, etc, and field access
>
> I know others share my feelings because many have articulated the very
> same
> thoughts to me on numerous occasions, the attached/dettached state
> complicates the whole JPA process.  Having worked with a couple of
> commercial persistence APIs for a number of years, I don't really see
> the
> need for it. 
> 
> Why we have to open and close a entity service repeatedly doesn't make
> any
> sense to me,  if we want back to using basic JDBC calls we'd just
> open
> connection or create a connection pool at application start and close
> it at
> exist. The actual connection management should be transparent to the
> user
> once the connection pool has been established. Instead we now have to
> worry
> about creating an entity manager and working out if the entity is
> attached
> or detached. If you take a look at the list archives you will see that
> it is
> a significant issue for many people.
> 
> What I would envision is a static multithreaded EMF with no need for
> an
> entity manager that automatically manages attached and detached state,
> you
> still get lazy loading because the EMF is smart enough to lazy load
> unless
> the user accesses the lazy loaded field. The EMF would then persist or
> merge
> automatically depending on whether the entity is new or dirty.
> Building
> these smarts into the EMF would make things much easier especially for
> new
> users and frankly would make the code a whole lost tidier.
> 
> Chris
> 
> -----Original Message-----
> From: Craig L Russell [mailto:craig.russell@oracle.com] 
> Sent: Sunday, 30 May 2010 5:12 PM
> To: users@openjpa.apache.org
> Subject: Re: equals, hashcode, toString, etc, and field access
> 
> I'm interested in hearing what you would like to see with regard to  
> entities after the persistence context in which they were valid no  
> longer exists.
> 
> Thanks,
> 
> Craig
> 
> On May 28, 2010, at 7:18 AM, C N Davies wrote:
> 
> > Darryl is right, I fought with this one for some time then it dawned
>  
> > upon me
> > that I was dealing with a detached entity that had a lazy loaded  
> > field. The
> > result of toString is like picking the lottery numbers.. pot luck! 
> 
> > Now do
> > the same thing with runtime enhancement during development and  
> > deploy it
> > with build time enhancement.
> >
> > Yet another reason to drag the JPA spec into the 20th century and do
>  
> > away
> > with this whole attached / detached state business.
> >
> > Chris
> >
> >
> >
> > -----Original Message-----
> > From: Daryl Stultz [mailto:daryl.stultz@opentempo.com]
> > Sent: Friday, 28 May 2010 10:23 PM
> > To: users@openjpa.apache.org
> > Subject: Re: equals, hashcode, toString, etc, and field access
> >
> > On Thu, May 27, 2010 at 8:49 PM, Trenton D. Adams
> > <trent@trentonadams.ca>wrote:
> >
> >>
> >> I mean I know if I'm doing lazy loading, toString won't get all the
>  
> >> data,
> >> cause it hasn't been enhanced.
> >
> >
> > Assuming the object is detached, yes. I believe the JPA spec does
> not
> > specify the behavior for attempted access of an unloaded property on
> a
> > detached entity. I believe OpenJPA returns null. This makes it very
> > difficult to tell if an association is null or not loaded. I have  
> > configured
> > OpenJPA to disallow access to unloaded properties of detached  
> > entities to
> > avoid the confusion. This means a toString method like yours in my 
> 
> > project
> > could crash.
> >
> > -- 
> > Daryl Stultz
> > _____________________________________
> > 6 Degrees Software and Consulting, Inc.
> > http://www.6degrees.com
> > http://www.opentempo.com
> > mailto:daryl.stultz@opentempo.com
> >
> 
> Craig L Russell
> Architect, Oracle
> http://db.apache.org/jdo
> 408 276-5638 mailto:Craig.Russell@oracle.com
> P.S. A good JDO? O, Gasp!


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