# Using an unmapped discriminator value in HQL

**URL:** <https://discourse.hibernate.org/t/using-an-unmapped-discriminator-value-in-hql/7999>\
**Category:** Hibernate ORM\
**Created:** [July 21, 2023, 4:41pm UTC](https://discourse.hibernate.org/t/using-an-unmapped-discriminator-value-in-hql/7999 "2023-07-21T16:41:24Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![gtoison](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/gtoison/32/3069_2.png) [@gtoison](https://discourse.hibernate.org/u/gtoison)\
**Post date:** [July 21, 2023, 4:41pm UTC](https://discourse.hibernate.org/t/using-an-unmapped-discriminator-value-in-hql/7999/1 "2023-07-21T16:41:24Z")

</div>

Hello,  
I’m upgrading an application from Hibernate 5.6 to 6.2 and running into the case where a query fails with an error:

```auto
session
.createQuery("select s.code, type(s) from MyEntity s where s.class != 'XYZ'")
.list()

```

The `"XYZ"` value does not correspond to any mapped class, from what I understood Hibernate tries to find the java class for that discriminator value and that’s where the exception occurs:

```auto
java.lang.NullPointerException: Cannot invoke "org.hibernate.metamodel.mapping.DiscriminatorValueDetails.getIndicatedEntity()" because "discriminatorDetails" is null
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitLiteral(BaseSqmToSqlAstConverter.java:5309) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitLiteral(BaseSqmToSqlAstConverter.java:434) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.tree.expression.SqmLiteral.accept(SqmLiteral.java:65) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitComparisonPredicate(BaseSqmToSqlAstConverter.java:7316) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitComparisonPredicate(BaseSqmToSqlAstConverter.java:434) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.tree.predicate.SqmComparisonPredicate.accept(SqmComparisonPredicate.java:104) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitWhereClause(BaseSqmToSqlAstConverter.java:2471) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitQuerySpec(BaseSqmToSqlAstConverter.java:2048) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitQuerySpec(BaseSqmToSqlAstConverter.java:434) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.tree.select.SqmQuerySpec.accept(SqmQuerySpec.java:125) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.spi.BaseSemanticQueryWalker.visitQueryPart(BaseSemanticQueryWalker.java:221) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitQueryPart(BaseSqmToSqlAstConverter.java:1902) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitSelectStatement(BaseSqmToSqlAstConverter.java:1587) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.visitSelectStatement(BaseSqmToSqlAstConverter.java:434) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.tree.select.SqmSelectStatement.accept(SqmSelectStatement.java:222) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.sql.BaseSqmToSqlAstConverter.translate(BaseSqmToSqlAstConverter.java:770) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.buildCacheableSqmInterpretation(ConcreteSqmSelectQueryPlan.java:345) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.withCacheableSqmInterpretation(ConcreteSqmSelectQueryPlan.java:268) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.performList(ConcreteSqmSelectQueryPlan.java:244) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.sqm.internal.QuerySqmImpl.doList(QuerySqmImpl.java:518) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
	at org.hibernate.query.spi.AbstractSelectionQuery.list(AbstractSelectionQuery.java:367) ~[hibernate-core-6.2.7.Final.jar:6.2.7.Final]
...

```

Can you please advise if that use-case is no longer supported in 6.2 (or if it was never supposed to work)?

---

<div class="post-metadata">

**Author:** ![beikov](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/beikov/32/258_2.png) [@beikov](https://discourse.hibernate.org/u/beikov)\
**Post date:** [July 24, 2023, 10:24am UTC](https://discourse.hibernate.org/t/using-an-unmapped-discriminator-value-in-hql/7999/2 "2023-07-24T10:24:06Z")

</div>

You can create JIRA ticket for this, but I seriously doubt that this was ever considered supported and just worked by chance. You should rather spell out the entity name for the thing that has the discriminator `XYZ` i.e. `s.class != com.mycompany.MyEntityXyz`.

---

<div class="post-metadata">

**Author:** ![gtoison](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/gtoison/32/3069_2.png) [@gtoison](https://discourse.hibernate.org/u/gtoison)\
**Post date:** [July 24, 2023, 4:17pm UTC](https://discourse.hibernate.org/t/using-an-unmapped-discriminator-value-in-hql/7999/3 "2023-07-24T16:17:48Z")

</div>

Thanks for the answer, I’ll change my code so it does not use something that wasn’t really supposed to work