[jira] [Created] (OPENJPA-2553) JPQL AVG returns Int instead of Double wrt. @ElementCollection

["Apache Fan (JIRA)" <ji...@apache.org>]

Apache Fan created OPENJPA-2553:
-----------------------------------

             Summary: JPQL AVG returns Int instead of Double wrt. @ElementCollection
                 Key: OPENJPA-2553
                 URL: https://issues.apache.org/jira/browse/OPENJPA-2553
             Project: OpenJPA
          Issue Type: Bug
          Components: query
    Affects Versions: 2.4.0
         Environment: Apache Tomee plus 1.7.1, openjpa-2.4.0-nonfinal-1598334.jar, hsqldb-2.3.2, H2DB-2014-12-19
            Reporter: Apache Fan


The following JPQL query is executed to get the average of values stored in a Map. 

{noformat}
@NamedQueries({
  @NamedQuery(name = "selectFromMap", 
      query = "SELECT new dao.entity.AggregationResultHolder(AVG(p), KEY(p)) FROM Evaluation e, IN (e.scores) p "
              + "WHERE e.subject.id=:subjectId GROUP BY KEY(p)")
})
{noformat}

Entity:
{noformat}
public class Evaluation {
...
  @ElementCollection
  @MapKeyColumn(name = "criteria_id") 
  @Column(name = "criteria_score")
  private Map<Criteria, Integer> scores = new HashMap<Criteria, Integer>();
...
}
{noformat}

- *Expected behaviour:* the AVG value is returned as Double (according to http://openjpa.apache.org/builds/2.3.0/apache-openjpa/docs/jpa_langref.html#jpa_langref_aggregates )
- *Experienced behaviour:* the average is returned as Integer (and exception is thrown if the AggregationResultHolder class' constructor is not Integer-based). Unfortunately this way the fraction digits are lost.

*Workaround:* after modifying the Map to <Criteria, Double> in the entity, the query returns Doubles for the average (however the fraction digits are still lost in case of HSQLDB). Obviously it is a sub-optimal solution, as the schema has to be changed.
 



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