When a user does not explicitly register a function on the Dialect selected a NullPointerException is thrown without much reason as to why. I would like to suggest handling this problem more gracefully to notify the user of the mistake.
Consider the following:
{code:title=Animal.java|borderStyle=solid}
@Entity
@Table( name = "ANIMAL" )
public class Animal {
private Long id;
private Animal mother;
private Animal father;
private String name;
private Date born;
}
{code}
{code:title=JPA Criteria Query|borderStyle=solid}
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<HumanPojo> criteria = cb.createQuery( HumanPojo.class );
Root<Human> root = criteria.from( Human.class );
criteria.select(
cb.construct(
HumanPojo.class,
root.get(Human_.id),
root.get(Human_.name),
cb.function(
"convert",
String.class,
root.get(Human_.born),
cb.literal(110))
)
);
em.createQuery( criteria ).getResultList();
{code}
In this scenario I am trying to utilize the CONVERT() function provided by SQL Server 2005+. When the query is executed I am presented with the following stack trace.
{code:title=Stack Trace|borderStyle=solid}
CriteriaBuilder cb = em java . getCriteriaBuilder lang.NullPointerException
at org.hibernate.internal.util.ReflectHelper.getConstructor ( ReflectHelper.java:309 ) ;
CriteriaQuery at org.hibernate.hql.internal.ast.tree.ConstructorNode.resolveConstructor(ConstructorNode.java:174)
at org.hibernate.hql.internal.ast.tree.ConstructorNode.prepare(ConstructorNode.java:144)
at org.hibernate.hql.internal.ast.HqlSqlWalker.processConstructor(HqlSqlWalker.java:1163)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:2354)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExprList(HqlSqlBaseWalker.java:2220)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectClause(HqlSqlBaseWalker.java:1495)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:583)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:311)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:259)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:262)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:190)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:142)
at org.hibernate.engine.query.spi.HQLQueryPlan. < HumanPojo init > criteria = cb.createQuery ( HumanPojo HQLQueryPlan . class java:115 ) ;
Root at org.hibernate.engine.query.spi.HQLQueryPlan. < Human init > root = criteria (HQLQueryPlan . from java:76)
at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan ( Human QueryPlanCache . class java:150 ) ;
at org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:302)
criteria at org . select hibernate.internal.AbstractSessionImpl.createQuery (
cb AbstractSessionImpl . construct java:240)
at org.hibernate.internal.SessionImpl.createQuery (
HumanPojo SessionImpl . class,
root java:1907)
at org . get hibernate.jpa.spi.AbstractEntityManagerImpl.createQuery ( Human_ AbstractEntityManagerImpl . id java:531 ) ,
root
at org . get hibernate.jpa.criteria.CriteriaQueryImpl$1.buildCompiledQuery ( Human_ CriteriaQueryImpl . name java:319 ) ,
cb
at org . function hibernate.jpa.criteria.compile.CriteriaCompiler.compile ( CriteriaCompiler.java:130)
"convert",
String at org . class,
root hibernate . get jpa.spi.AbstractEntityManagerImpl.createQuery ( Human_ AbstractEntityManagerImpl . born java:699 ) ,
cb
at sun . literal reflect.NativeMethodAccessorImpl.invoke0 ( 110 Native Method )
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62 )
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43 )
at java.lang.reflect.Method.invoke(Method.java:497 ) ;
at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:344)
em at com . sun.proxy.$Proxy73. createQuery( criteria Unknown Source )
at sun . getResultList reflect.NativeMethodAccessorImpl.invoke0 ( Native Method ) ;
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:294)
at com.sun.proxy.$Proxy73.createQuery(Unknown Source)
{code}
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