Possible bug using CASE WHEN on GROUP BY clause

Having problem when I create a SELECT query with CASE WHEN and use this same CASE on a GROUP BY clause.

My query (listPeople() method):

public class PersonDAO {

    @Inject
    private SessionFactory sessionFactory;

    public Session getSession() {
        return sessionFactory.getCurrentSession();
    }

    protected JPQLQuery<Person> newQuery() {
        return new HibernateQuery<Person>(this.getSession());
    }

    public List<Tuple> listPeople() {
        StringExpression caseExpr = new CaseBuilder() //
                .when(person.type.eq("male")).then("M") //
                .when(person.status.ne("ACTIVE")).then("I") //
                .otherwise("O");

        return newQuery() //
                .from(QPerson.person) //
                .groupBy(caseExpr) //
                .select(caseExpr.as("test"), person.count()) //
                .fetch();
    }
}

My entity/table mapping:

@Entity
@Table(name = "PER_PERSON")
public class Person implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "PER_ID")
    private Long              id;

    @Column(name = "pes_tp", nullable = false)
    private String            type;

    @Column(name = "pes_st", nullable = false)
    private String            status;

    public Person() {
        super();
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }
}

The DDL to create the table:

CREATE TABLE per_person 
(
  PER_ID   INTEGER,
  pes_tp   VARCHAR,
  pes_st   VARCHAR,
  PRIMARY KEY (per_id)
);

The generated SQL seems to be OK, but the database shows an error telling me I have to put PER_PERSON.PES_TP on the SELECT clause. Here’s the QueryDSL genereted SQL:

SELECT CASE
         WHEN person0_.pes_tp = 'male' THEN 'M'
         WHEN person0_.pes_st <> 'ACTIVE' THEN 'I'
         ELSE 'O'
       END AS col_0_0_,
       COUNT(person0_.PER_ID) AS col_1_0_
FROM PER_PERSON person0_
GROUP BY CASE
         WHEN person0_.pes_tp = 'male' THEN 'M'
         WHEN person0_.pes_st <> 'ACTIVE' THEN 'I'
         ELSE 'O'
     END;

If I run this SQL on the database, it runs successfully. But here’s the stacktrace of the exception thrown:

Hibernate: select case when person0_.pes_tp=? then ? when person0_.pes_st<>? then ? else 'O' end as col_0_0_, count(person0_.PER_ID) as col_1_0_ from PER_PERSON person0_ group by case when person0_.pes_tp=? then ? when person0_.pes_st<>? then ? else 'O' end
2017-08-29 21:09:10 WARN  SqlExceptionHelper:144 - SQL Error: 0, SQLState: 42803
2017-08-29 21:09:10 ERROR SqlExceptionHelper:146 - ERROR: column "person0_.pes_tp" must appear in the GROUP BY clause or be used in an aggregate function
  Posição: 18
2017-08-29 21:09:10 INFO  JdbcCoordinatorImpl:298 - HHH000106: Forcing container resource cleanup on transaction completion

Caused by: org.hibernate.exception.SQLGrammarException: could not extract ResultSet
	at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:123)
	at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
	at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
	at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
	at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:91)
	at org.hibernate.loader.Loader.getResultSet(Loader.java:2066)
	at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1863)
	at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1839)
	at org.hibernate.loader.Loader.doQuery(Loader.java:910)
	at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:355)
	at org.hibernate.loader.Loader.doList(Loader.java:2554)
	at org.hibernate.loader.Loader.doList(Loader.java:2540)
	at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2370)
	at org.hibernate.loader.Loader.list(Loader.java:2365)
	at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:497)
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:387)
	at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:236)
	at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1300)
	at org.hibernate.internal.QueryImpl.list(QueryImpl.java:103)
	at com.querydsl.jpa.hibernate.AbstractHibernateQuery.fetch(AbstractHibernateQuery.java:174)
	at br.com.dataeasy.chronus.persistencia.hibernate.dao.RelatorioQuadroGeralDAO.listPeople(RelatorioQuadroGeralDAO.java:65)
	at br.com.dataeasy.chronus.persistencia.hibernate.dao.RelatorioQuadroGeralDAO.listar(RelatorioQuadroGeralDAO.java:92)
	at br.com.dataeasy.chronus.service.RelatorioQuadroGeralService.consultar(RelatorioQuadroGeralService.java:71)
	at br.com.dataeasy.chronus.service.RelatorioQuadroGeralService.gerarRelatorio(RelatorioQuadroGeralService.java:83)
	at br.com.dataeasy.chronus.service.RelatorioQuadroGeralService$$FastClassBySpringCGLIB$$bdfcdfdb.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
	at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673)
	at br.com.dataeasy.chronus.service.RelatorioQuadroGeralService$$EnhancerBySpringCGLIB$$a55881d.gerarRelatorio(<generated>)
	at WICKET_br.com.dataeasy.chronus.service.RelatorioQuadroGeralService$$FastClassByCGLIB$$bdfcdfdb.invoke(<generated>)
	at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
	at org.apache.wicket.proxy.LazyInitProxyFactory$AbstractCGLibInterceptor.intercept(LazyInitProxyFactory.java:350)
	at WICKET_br.com.dataeasy.chronus.service.RelatorioQuadroGeralService$$EnhancerByCGLIB$$b30eabd1.gerarRelatorio(<generated>)
	at br.com.dataeasy.chronus.web.wicket.pages.relatorio.quadrogeral.RelatorioQuadroGeralPage.doDownloadArquivo(RelatorioQuadroGeralPage.java:77)
	at br.com.dataeasy.chronus.web.wicket.components.botoes.BotaoGerarRelatorio$1.getResourceStream(BotaoGerarRelatorio.java:51)
	at br.com.dataeasy.chronus.web.wicket.components.link.AjaxDownload.onRequest(AjaxDownload.java:40)
	... 79 more
Caused by: org.postgresql.util.PSQLException: ERROR: column "person0_.pes_tp" must appear in the GROUP BY clause or be used in an aggregate function
  Posição: 18
	at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2455)
	at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2155)
	at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:288)
	at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:430)
	at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:356)
	at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:168)
	at org.postgresql.jdbc.PgPreparedStatement.executeQuery(PgPreparedStatement.java:116)
	at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:82)
	... 115 more

I’m using the following environment:

• Java: 1.8.0_144
• Hibernate: 4.3.10, JPA 2.1
• QueryDSL: 4.0.6 (tried this example on 4.1.0 too)
• DBMS: PostgreSQL 9.6

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[orzecho]

I don’t know if it’s just a workaround or proper way to do this but it seems to resolve the problem: https://stackoverflow.com/questions/23887678/querydsl-case-expression-with-string-value

[stale[bot]]

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