EclipseLink throws JPQLException on using SELECT ... AS in a constructor expression

Question

I have a JPQL query with a constructor expression using EclipseLink 2.7.5.

It fails with:

Caused by: Exception [EclipseLink-0] (Eclipse Persistence Services - 2.7.5.v20191016-ea124dd158): org.eclipse.persistence.exceptions.JPQLException
Exception Description: Syntax error parsing [
            SELECT NEW net.bbstats.dto.PlayerStatDto(
              gl.playerId,
              gl.seasonStartYear,
              gl.lastName,
              gl.firstName,
              gl.incognito,
              COUNT(DISTINCT gl.gameId) AS games,
              SUM(CASE WHEN gl.hasPlayed = FALSE THEN 1 ELSE 0 END) AS gamesplayed,
              SUM(CASE WHEN gl.starter = TRUE THEN 1 ELSE 0 END) AS gamesstarted,
              SUM(gl.threePointersMade),
              SUM(gl.freeThrowsMade),
              SUM(gl.freeThrowsAttempted),
              SUM(gl.personalFouls),
              SUM(CASE WHEN gl.personalFouls >= 5 THEN 1 ELSE 0 END),
              SUM(gl.points) AS points,
              MAX(gl.points),
              MIN(gl.points)
            )
            FROM GameLog gl
            WHERE gl.roundId = :roundId AND gl.groupCode = :groupCode AND gl.rosterId IN :rosterIds
            GROUP BY
              gl.playerId,
              gl.seasonStartYear,
              gl.lastName,
              gl.firstName,
              gl.incognito
            ORDER BY gamesstarted DESC, games DESC, points DESC, gl.lastName, gl.firstName
        ]. 
[140, 141] The constructor expression has two constructor items ('COUNT(DISTINCT gl.gameId)' and 'AS games') that are not separated by a comma.
[204, 205] The constructor expression has two constructor items ('SUM(CASE WHEN gl.hasPlayed = FALSE THEN 1 ELSE 0 END)' and 'AS gamesplayed') that are not separated by a comma.
[271, 272] The constructor expression has two constructor items ('SUM(CASE WHEN gl.starter = TRUE THEN 1 ELSE 0 END)' and 'AS gamesstarted') that are not separated by a comma.
[462, 463] The constructor expression has two constructor items ('SUM(gl.points)' and 'AS points') that are not separated by a comma.
[141, 149]  The expression is invalid, which means it does not follow the JPQL grammar.
[205, 219]  The expression is invalid, which means it does not follow the JPQL grammar.
[272, 287]  The expression is invalid, which means it does not follow the JPQL grammar.
[463, 472]  The expression is invalid, which means it does not follow the JPQL grammar.
    at org.eclipse.persistence.internal.jpa.jpql.HermesParser.buildException(HermesParser.java:157)
    at org.eclipse.persistence.internal.jpa.jpql.HermesParser.validate(HermesParser.java:336)
    at org.eclipse.persistence.internal.jpa.jpql.HermesParser.populateQueryImp(HermesParser.java:280)
    at org.eclipse.persistence.internal.jpa.jpql.HermesParser.buildQuery(HermesParser.java:165)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:142)
    at org.eclipse.persistence.internal.jpa.JPAQuery.processJPQLQuery(JPAQuery.java:225)
    at org.eclipse.persistence.internal.jpa.JPAQuery.prepare(JPAQuery.java:186)
    at org.eclipse.persistence.queries.DatabaseQuery.prepareInternal(DatabaseQuery.java:631)
    at org.eclipse.persistence.internal.sessions.AbstractSession.processJPAQuery(AbstractSession.java:4502)
    at org.eclipse.persistence.internal.sessions.AbstractSession.processJPAQueries(AbstractSession.java:4462)
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.initializeDescriptors(DatabaseSessionImpl.java:645)
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.postConnectDatasource(DatabaseSessionImpl.java:868)
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:811)
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:256)
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:772)
    ... 201 more

This is working on Hibernate. I thought this would be standard JPA 2.2 or even JPA 2.1 to put an AS clause after the SELECT ..., so that you can reuse the identifier for the ORDER BY etc. clauses.

Q's:

What's wrong? Is it an EclipseLink bug/missing feature? Is it not supposed to work like that, because Hibernate has some extra meat here?

How can you work around this in a constructor expression (without having to repeat the expressions in the ORDER BY clause)?

Also asked in the forums here: https://www.eclipse.org/forums/index.php/m/1819241/ — Kawu, Jan 10 '20 at 11:50

Mikko Maunu · Accepted Answer · 2020-01-11T16:12:16.180

That is indeed invalid JPQL, because select_item is not an constructor_item. Below is the syntax of SELECT clause taken from JPA 2.2 Specification:

select_clause ::= SELECT [DISTINCT] select_item {, select_item}* 
select_item ::= select_expression [ [AS] result_variable]
select_expression ::=
  single_valued_path_expression | 
  scalar_expression |
  aggregate_expression |
  identification_variable | 
  OBJECT(identification_variable) |
  constructor_expression
constructor_expression ::= 
  NEW constructor_name ( constructor_item {, constructor_item}* )

constructor_item ::=
  single_valued_path_expression |
  scalar_expression |
  aggregate_expression |
  identification_variable
aggregate_expression ::= 
  { AVG | MAX | MIN | SUM} ([DISTINCT] state_valued_path_expression) |
  COUNT ([DISTINCT] identification_variable | state_valued_path_expression
    |single_valued_object_path_expression) |
  function_invocation

I'm afraid there is no workaround that avoids repeating in this case.

EclipseLink throws JPQLException on using SELECT ... AS in a constructor expression

1 Answers1