Re: [Springframework-developer] Question/ potential patch for org.springframework.orm.hibernate3.HibernateTemplate

[Colin Y. <col...@gm...>]

OK, so I learned something today :)

Calling session.load (and hibernateTemplate.load) for a single non-final,
non-proxied class does *not* hit the database even though the javadocs imply
it will, so the loading of the class is (as you original stated) lazy.
Marking the class as lazy=false forces hibernate to check that the row
exists, but by default it doesn't.  If I understand this right, the only
time and exception is thrown on session.load is if the class is not
lazy.....

I still think Spring is doing the right thing in being consistent with
Hibernate's behaviour.

I learn something new every day :)  Sorry for the noise.

Col

On 26/07/06, Colin Yates <col...@gm...> wrote:
>
> Actually, althought the javadoc doesn't explicitly mention it (and is
> quite badly worded actually) load won't hit the database if your class is
> proxied.  This is mentioned in the reference documentation (section 10.3)
> and is encapsulated in the
> org.hibernate.event.def.DefaultLoadEventListener.
>
> Given these semantics are defined by Hibernate I am not really sure that
> Spring should change the behaviour as it would quite unintuitive.
>
> To our original question, I believe even if the class *is* lazy loaded,
> load would still hit the database to confirm identity but that is an
> assumption and I haven't traced it through to verify that behaviour.  The
> Javadocs do make it clear that load should only be used for known persistent
> objects, if in doubt, use get.
>
> Col
>
> P.S.  I think I will write a couple of tests to verify this behaviour and
> will get back to you.
>
>
> On 26/07/06, Colin Yates < col...@gm...> wrote:
> >
> > Hi Bill,
> >
> > Hibernate3 only makes relationships lazy by default, not the class.
> > This is sensible (in my opinion) because most of the time there is no real
> > reason to load the class in seperate chunks (aka field groups).   I
> > believe that they actually mention in their documentation that they only
> > support lazy loading of the class in order to "tick a box" :)
> >
> > Also, checking out the hibernate document for the hibernate Session ( http://hibernate.org/hib_docs/v3/api/org/hibernate/Session.html#load(java.lang.Class,%20java.io.Serializable)
> >
> > <http://hibernate.org/hib_docs/v3/api/org/hibernate/Session.html#load%28java.lang.Class,%20java.io.Serializable%29>)
> > indicates that the load methods *do* check that the object exists.  So
> > hibernate will throw its HibernateException and Spring will then convert
> > this into one of its own DataAccessException.
> >
> > HTH.
> >
> >  On 26/07/06, Bill Six <bil...@ya...> wrote:
> >
> > > Hi,
> >
> > I have a question about the load() methods on
> > hibernate3's HibernateTemplate.
> >
> > Spring's javadoc for load() say that an exception will
> > be thrown if the object is not found.  However, from
> > what I understand, Hibernate 3 changed its default
> > behavior to lazy load all classes.  This means that if
> > you try to load an object with an ID that does not
> > exist, a Hibernate error is not thrown because you get
> > a proxy to the object that does not exist.  It is only
> > upon the first method call to that proxy that
> > Hibernate's ObjectNotFoundException is thrown.  I
> > would think that in Spring's load() methods should
> > force initilization of that object so that trying to
> > load an object that does not exist immediately throws
> > the correct Spring exception.
> >
> > I have attached a patch that should do the trick.  I
> > have never made a patch before, nor have I ever looked
> > through the source of spring or hibernate, so please
> > excuse any stupid mistakes :-)
> >
> > Thanks for a great product,
> >
> > Bill Six
> >
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