Lazy initialization problem

thorstenschaefer · **Joined:** Fri Nov 28, 2003 6:57 am **Posts:** 20

Hi,

I've a business object which contains a set and this set is configured as lazy loading. My test class looks like this (pseudo code):

public class Testclass {
protected Session session = null;
protected Iterator iterator;

Testclass {
// initialize session and iterator; the iterator iterates over my business object
}

public static void main() {
// use the iterator to iterate over the BOs...
int children = businessObject.getSet.size(); // this call fails!
}
}

I get the following Exception: net.sf.hibernate.LazyInitializationException: Failed to lazily initialize a collection - no Session

I never closed the session (the documentation tells me not to do it). Can somebody tell me where the problem is? Could it be a problem that the method is static and the session not? Or that the session is "blocked" by the iterator?

Thanks,

Thorsten

michael · **Posted:** Mon Jan 19, 2004 11:32 am

Please show your real code.

emmanuel · **Posted:** Mon Jan 19, 2004 11:34 am

The session has been closed. Show a simplified but real code.
The undeplying collectino keep a session reference to lazy load.

thorstenschaefer · **Joined:** Fri Nov 28, 2003 6:57 am **Posts:** 20

Here's the code:

Code:

public class ManualMatcherFacade {
 private static final String QUERY = ...;
 protected Session session = null;
 protected Iterator iterator;
 
 public ManualMatcherFacade() {
  try {
   session = PersistenceLayer.getInstance().getSession();
   iterator = EntityManager.genericIterator(session, QUERY);
  } catch (DataException e) {}
 }
   
 public static void main(String[] args) throws Exception {
  ManualMatcherFacade m = new ManualMatcherFacade();
  for (int i=0; i<10; i++) {
   // for each possible vendor
   Object[] o = (Object[]) m.next();
   Integer key = (Integer) o[0];
   NormalizedVendor vendor = NormalizedVendorManager.findByPrimaryKey(key);
   System.out.println("Size: " + vendor.getComparisonResults().size());
 }
}

And that's the mapping of the set in NormalizedVendor:

Code:

<set name="comparisonResults" table="ETL2_MAP_VENDOR_CR" lazy="true">
 <key>
  <column name="VENDOR" not-null="true"/>
 </key>
 <many-to-many class="com.degussa.spr.dw.common.data.ComparisonResult">
  <column name="RESULT" not-null="true"/>
 </many-to-many>
</set>

[/code]

thorstenschaefer · **Joined:** Fri Nov 28, 2003 6:57 am **Posts:** 20

I just debugged the code and found the problem: the method to retrieve the vendor closed the session. The set has this session instead of the session defined in my class. I think I have too change my design a little bit...

By the way: does anybody know when the Hibernate book will be available? I'd appreciate a good book and the chapters I read are very good.

Bye,

Thorsten

christian · **Posted:** Mon Jan 19, 2004 12:01 pm

http://www.manning.com/bauer/

We are currently finishing the book, it will be available in the 2nd quarter 2004. I'm pushing to get some chapters earlier in the Manning Early Access Program (you pay for a subscription to the draft chapters as they go to production and receive a print copy when it is available), but don't expect anything before early March.