CODEWITHSUNDEEP
javahibernatespringpostgresql
Sabyrzhan
Sabyrzhan

Reputation: 175

Hibernate field multiple alias

I am having an entity, which has collections field (params). There can be many params. I want to make unique join for each unique param. i.e. p1.id = ? AND p2.id = ? AND p3.id = ? etc.

In Hibernate, when I try to create alias for the same field, it throws exception with message about duplicate alias.

How can I achieve multiple joins for the field?

I am using spring framework, hibernate and postgresql.

Thanks in advance.

Upvotes: 4

Views: 4229

Answers (1)

Adam Arold
Adam Arold

Reputation: 30528

I assume that you are using the Criteria API.

If you check the source code of Hibernate you can find the problem here:

CriteriaQueryTranslator#createAssociationPathCriteriaMap()

private void createAssociationPathCriteriaMap() {
        Iterator iter = rootCriteria.iterateSubcriteria();
        while ( iter.hasNext() ) {
            CriteriaImpl.Subcriteria crit = ( CriteriaImpl.Subcriteria ) iter.next();
            String wholeAssociationPath = getWholeAssociationPath( crit );
            Object old = associationPathCriteriaMap.put( wholeAssociationPath, crit );
            if ( old != null ) {
                throw new QueryException( "duplicate association path: " + wholeAssociationPath );
            }
            int joinType = crit.getJoinType();
            old = associationPathJoinTypesMap.put( wholeAssociationPath, new Integer( joinType ) );
            if ( old != null ) {
                // TODO : not so sure this is needed...
                throw new QueryException( "duplicate association path: " + wholeAssociationPath );
            }
        }
    }

I'm using Hibernate 3.3.2.

What happens internally is that When you are adding Criterias to your root Criteria Hibernate creates SubCriterias and later fills a Map (check the code below) with all the paths you are trying to use and if it finds a duplication it will throw an exception.

So for example if you are trying to join: entity0.entity1 and later you try to join that again you will get an Exception. It won't work even with an alias because Hibernate doesn't care about them here.

You can work around this if you don't join something twice OR you can use HQL/JPQL. You may check out newer versions of Hibernate but I'm not sure if they fixed this quasi-bug.

Upvotes: 2

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