when lazy=true,"left join fetch" gets duplicates

lizarb · **Joined:** Mon May 14, 2007 9:54 pm **Posts:** 3

Hi,

I have been confused with this problem for two days:(

Hibernate version:3
When lazy=false in xml,excute following code:

Code:

result = s.createCriteria(JtsUser.class)          
              .add(Restrictions.idEq(2))    
              .list();

result.size() is 1, this is correct.
But when lazy=true in xml,excute following in java:

Code:

result = s.createCriteria(JtsUser.class)          
              .setFetchMode("jtsHistories", FetchMode.JOIN)    
              .add(Restrictions.idEq(2))    
              .list();

result.size() is 4, 4 same objects! This is unreasonable because id is PK.

"jtsHistories" is a set of "JtsUser". The JtsUser that id=2 contains 4 records of jtsHistory(if 5, then 5 same objects).

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

It's the join that screwing your results up. Add "setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY)" to eliminate the one-root-entity-per-returned-row phenomenon that you're seeing.

lizarb · **Joined:** Mon May 14, 2007 9:54 pm **Posts:** 3

tenwit wrote:

It's the join that screwing your results up. Add "setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY)" to eliminate the one-root-entity-per-returned-row phenomenon that you're seeing.

Thanks a lot! But the "phenomenon" is... Is it a bug, or of some usage?

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

It's the correct result for the default result transformer. I don't know why DISTINCT_ROOT_ENTITY isn't the default one, as it's the one most people want most of the time, but there you go.