[hibernate-issues] [Hibernate-JIRA] Created: (HHH-2463) ClassCastException when Hibernate tries to cache results using ResultTransformer

[Peak user (JIRA)]

ClassCastException when Hibernate tries to cache results using ResultTransformer
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         Key: HHH-2463
         URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2463
     Project: Hibernate3
        Type: Bug

    Versions: 3.2.2    
    Reporter: Peak user


When Hibernate executes a cacheable query using a ResultTransformer, it will attempt to cache the results AFTER applying the ResultTransformer. The problem is that the ResultTransformer may modify the data in a way that Hibernate won't understand it anymore, and in this case it will generate a ClassCastException when trying to cache it.

This problem could be easily solved if Hibernate cached results before applying the ResultTransformer instead of afterwards.

Here's a sample code to reproduce this problem:


class ToMapResultTransformer implements ResultTransformer {
    private String[] properties;
    public ToMapResultTransformer(String[] properties) {
        this.properties = properties;
    }
    public List transformList(List collection) {
        return collection;
    }
    public Object transformTuple(Object[] tuple, String[] aliases) {
        Map<String,Object> result = new HashMap<String,Object>(tuple.length);
        for (int i=0; i<tuple.length; i++) {
            result.put((properties != null ? properties[i] : aliases[i]), tuple[i]);
        }
        return result;
    }
}

Criteria sqlCriteria = createSqlCriteria(session);
sqlCriteria.setProjection(projections);
sqlCriteria.setCacheable(true);
sqlCriteria.setResultTransformer(new ToMapResultTransformer(properties));
sqlCriteria.list();


The code above produces the following exception:

java.lang.ClassCastException: java.util.HashMap
	at org.hibernate.cache.StandardQueryCache.put(StandardQueryCache.java:83)
	at org.hibernate.loader.Loader.putResultInQueryCache(Loader.java:2185)
	at org.hibernate.loader.Loader.listUsingQueryCache(Loader.java:2129)
	at org.hibernate.loader.Loader.list(Loader.java:2087)
	at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:94)
	at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1569)
	at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:283)


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