Session.get() in combination whith cache and lazy="fals

kopo700 · **Posted:** Thu Apr 21, 2005 11:06 am

Session.get() in combination whith cache and lazy="false" broken???

I have trouble with Session.get() which is supposed to always return a non-proxied instance. Well it does not. Not even when using lazy="true". I also have caching enabled for the class. I have narrowed it down to the class org.hibernate.event.def.DefaultLoadEventListener

in the method proxyOrLoad (at around row number 227)

I actualy get a proxy back even though I have no proxies enabled. I might add that it works when the cache does not contain a value.

Is this as expected? Why does the cache usage change the behaviour?

Keep up the good work!

/Konstantin

Code:

      org.hibernate.event.def.DefaultLoadEventListenerin.proxyOrLoad  (at around row number 227)

      Object proxy = persistenceContext.getProxy(keyToLoad);
            if ( proxy != null ) { // <-- Execution enters this part /Konstantin
               log.trace("entity proxy found in session cache");
               Object impl;
               if ( options.isAllowProxyCreation() ) {
                  impl = null;
               }
               else {
                  //force initialization of the proxy
                  impl = ( (HibernateProxy) proxy ).getHibernateLazyInitializer().getImplementation();
               }
               // return existing or narrowed proxy
               Object narrowed = persistenceContext.narrowProxy( proxy, persister, keyToLoad, impl );
               return narrowed;
            }
            else if ( options.isAllowProxyCreation() ) {
               log.trace("creating new proxy for entity");
               // return new uninitialized proxy
               proxy = persister.createProxy( event.getEntityId(), event.getSession() );
               persistenceContext.getBatchFetchQueue().addBatchLoadableEntityKey(keyToLoad);
               persistenceContext.addProxy(keyToLoad, proxy);
               return proxy;
            }

mapping excrept:

<class name="CompositeElement" table="CMT_PROD_PAGE_ELEMENT"
lazy="false"
>

<cache usage="nonstrict-read-write" />
...

Hibernate version:3.01

max · **Posted:** Thu Apr 21, 2005 2:32 pm

get does not promise you will get a non-proxied class it just promise to fail if the entity is not in the db

kopo700 · **Posted:** Fri Apr 22, 2005 2:59 am

It does at least in Hibernate 2. I checked the book Hibernate in Action p141:

""...On the other hand, get() never returns a proxy."

But it did some more investigation I found the source for why proxies where enabled in this case. It was in the same class. in the method onLoad starting at row 54. Instead of triggering a loadtye of GET it triggered an INTERNAL_LOAD.

Sol I guess caching changes the behaviour of Hibernate?

/Konstantin

max · **Posted:** Fri Apr 22, 2005 3:29 am

hmm - the javadoc (and code) states the following:

"Return the persistent instance of the given entity class with the given identifier, or null if there is no such persistent instance. (If the instance, or a proxy for the instance, is already associated with the session, return that instance or proxy.)"

And that javadoc is the same in both H2.1 and H3.

The text in HiA is a bug IMO. I've asked us to update the errata with this info.

kopo700 · **Posted:** Fri Apr 22, 2005 3:33 am

Cool! Then I know.

max · **Posted:** Fri Apr 22, 2005 3:48 am

..and just to be precise the thing get() actually promises is the following:

It will return null instead of throwing an exception if the object cannot be found first in the session and *then* in the db.
Meaning if you have already queried or load'ed the object as an proxy get will just return that one.

-max