Mapping entity to pojo with aggregation with Hibernate

Question

I'm trying to create a list of POJOs from a NamedQuery that accesses an existing entity using Hibernate. I want to total the values in a mapped object into a "summary record" to use in a reporting structure of sorts, which is detailed below as "SummaryReportRollup". I tried rolling up these Headers programmatically, but there are so many that the performance was dreadful.

Here are my entities, including the mappings and excluding getters/setters/methods/un-important fields. SummaryReportRollup is defined at the bottom:

@Entity
@Table(name = "header")
@SequenceGenerator(name="header_seq", sequenceName="header_seq", allocationSize=1)
public class Header implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="header_seq")
    @Column(name = "head_id", insertable = true, updatable = false)
    private Long id;

    @OneToMany(fetch = FetchType.EAGER, cascade={CascadeType.ALL})
    @JoinColumn(name="head_id")
    private List<DetailLineItem> detailLineItems;

    @Column(name = "location", insertable = true, updatable = false)
    private String location;

    @Column(name = "proj_year_month", insertable = true, updatable = false)
    private String projectionYearMonth;

    /* ... getters and setters ... */
}


@Entity
@Table(name = "detail")
@SequenceGenerator(name="detail_seq", sequenceName="detail_seq", allocationSize=1)
public class DetailLineItem implements Cloneable, Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="detail_seq")
    @Column(name = "detail_id")
    private Long id;

    @ManyToOne
    @JoinColumn(name="head_id", unique=false, nullable=false)
    @JsonIgnore
    private Header header;

    @ManyToOne
    @JoinColumn(name="attrib_id", unique=false, nullable=false)
    private Attribute attribute;

    private Double value;
    /* ... getters and setters ... */
}

@Entity
@Table(name = "attribute")
@SequenceGenerator(name="attribute_seq", sequenceName="attribute_seq", allocationSize=1)
public class Attribute implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="attribute_seq")
    @Column(name = "attrib_id", insertable = false, updatable = false)
    private Long id;

    @Column(name = "name", insertable = false, updatable = false)
    private String name;

    @Column(name = "mandatory_in", insertable = false, updatable = false)
    private char mandatoryIndicator;

    @Column(name = "negative_in", insertable = false, updatable = false)
    private char negativeIndicator;

    @Column(name = "decimal_in", insertable = false, updatable = false)
    private char decimalIndicator;

    /* ... getters and setters ... */
}

public class SummaryReportRollup {

    private String projectionYearMonth;
    private Attribute attribute;
    private Double value;
    /* ... getters and setters ... */
}

Here is my named query to populate SummaryReportRollup ...

    @NamedQuery(name = "findSummaryReportRollups", query = "select new SummaryReportRollup(h.projectionYearMonth, h.detailLineItems.attribute, sum(h.detailLineItems.value))  from Header h " +
         " where location in (:locations) group by projectionYearMonth, detailLineItems.attribute ")    

This is the error I receive from Hibernate ...

ERROR: HHH000177: Error in named query: findSummaryReportRollups
Throwable occurred: org.hibernate.QueryException: illegal attempt to dereference collection [header0_.head_id.detailLineItems] with element property reference [attribute] [select new SummaryReportRollup(h.projectionYearMonth, h.detailLineItems.attribute, sum(h.detailLineItems.value))  from com.rac.projections.domain.Header h  where location in (:locations) group by projectionYearMonth, detailLineItems.attribute ]
    at org.hibernate.hql.internal.ast.tree.DotNode$1.buildIllegalCollectionDereferenceException(DotNode.java:68)
    at org.hibernate.hql.internal.ast.tree.DotNode.checkLhsIsNotCollection(DotNode.java:550)
    at org.hibernate.hql.internal.ast.tree.DotNode.resolve(DotNode.java:234)
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:118)
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:114)
    at org.hibernate.hql.internal.ast.tree.DotNode.resolveSelectExpression(DotNode.java:660)
    at org.hibernate.hql.internal.ast.HqlSqlWalker.resolveSelectExpression(HqlSqlWalker.java:893)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:2079)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.constructor(HqlSqlBaseWalker.java:2373)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:2146)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExprList(HqlSqlBaseWalker.java:2016)    
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectClause(HqlSqlBaseWalker.java:1451)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:571)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:299)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:247)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:248)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:183)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:105)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:168)
    at org.hibernate.internal.SessionFactoryImpl.checkNamedQueries(SessionFactoryImpl.java:1032)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:506)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1750)
    at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:94)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:905)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:890)
    at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:74)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:225)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:308)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:398)
    at org.springframework.beans.factory.BeanFactoryUtils.beansOfTypeIncludingAncestors(BeanFactoryUtils.java:275)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.detectPersistenceExceptionTranslators(PersistenceExceptionTranslationInterceptor.java:139)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.<init>(PersistenceExceptionTranslationInterceptor.java:79)
    at org.springframework.dao.annotation.PersistenceExceptionTranslationAdvisor.<init>(PersistenceExceptionTranslationAdvisor.java:70)
    at org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor.setBeanFactory(PersistenceExceptionTranslationPostProcessor.java:99)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeAwareMethods(AbstractAutowireCapableBeanFactory.java:1439)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1408)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:710)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:410)
    at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:84)
    at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:1)
    at org.springframework.test.context.TestContext.loadApplicationContext(TestContext.java:280)
    at org.springframework.test.context.TestContext.getApplicationContext(TestContext.java:304)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:109)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75)
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:321)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:220)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:301)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:303)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:240)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:180)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Is this the wrong approach? What is it that I'm doing wrong here?

Sorry for the long post - I appreciate your help!

Answer 1

To fix "illegal attempt to dereference collection" exception you need to create alias for your detailLineItems and then use it in your projection constructor

Try Modifying your query as

@NamedQuery(name = "findSummaryReportRollups", query = "select new SummaryReportRollup(h.projectionYearMonth, detailLineItems.attribute, sum(detailLineItems.value))  from Header h inner join h.detailLineItems detailLineItems " +
         " where location in (:locations) group by projectionYearMonth, detailLineItems.attribute ")