spring batch HibernateCursorItemReaderBuilder throws QuerySyntaxException

Question

I've a batch program based on Spring batch. The item reader is reading data from a database and I'm using the class HibernateCursorItemReaderBuilder in order to setup the reader . But Hibernate doesn't recognise the location of Entities, and throws an hibernate exception : QuerySyntaxException ( Instrument is not mapped)
The JPA Entities are definitely present in my project, otherwise the code would not compile.

After debugging I found out the following. SessionFactoryImpl has an object called MetamodelImpl. And the properties this object are not set. One of the properties is called entityPersisterMap. This is where all Entities are registred. The solution is to set the property metamodel on SessionFactoryImpl. But there is no such method.

@Configuration
public class ItemReaderConfig {
    
    @Autowired
    EntityManagerFactory entityManagerFactory;
    
    @Bean
    public HibernateCursorItemReader<Instrument> hibernateCursorItemReader() {
        
        SessionFactory sessionFactory = entityManagerFactory.unwrap(SessionFactory.class);
        
        return new HibernateCursorItemReaderBuilder<Instrument>()
                .name("instrumentReader")
                .sessionFactory(sessionFactory)
                .entityClass(Instrument.class)
                .queryString("from Instrument instr order by name") 
                .build();
    }
}

    org.springframework.batch.item.ItemStreamException: Failed to initialize the reader
        at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:153) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.support.CompositeItemStream.open(CompositeItemStream.java:103) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.core.step.tasklet.TaskletStep.open(TaskletStep.java:311) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:205) [spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:148) [spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.core.job.AbstractJob.handleStep(AbstractJob.java:410) [spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.core.job.SimpleJob.doExecute(SimpleJob.java:136) [spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:319) [spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:147) [spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) [spring-core-5.2.5.RELEASE.jar:5.2.5.RELEASE]
        at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:140) [spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
        at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
        at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
        at java.lang.reflect.Method.invoke(Method.java:564) ~[?:?]
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) [spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:198) [spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) [spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
        at org.springframework.batch.core.configuration.annotation.SimpleBatchConfiguration$PassthruAdvice.invoke(SimpleBatchConfiguration.java:127) [spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) [spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) [spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
        at com.sun.proxy.$Proxy75.run(Unknown Source) [?:?]
        at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.execute(JobLauncherCommandLineRunner.java:192) [spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.executeLocalJobs(JobLauncherCommandLineRunner.java:166) [spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.launchJobFromProperties(JobLauncherCommandLineRunner.java:153) [spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.run(JobLauncherCommandLineRunner.java:148) [spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:784) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:768) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:322) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
        at com.chartinvestbatch.alphaVantageHistory.configuration.Application.main(Application.java:22) [classes/:?]
    Caused by: java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: Instrument is not mapped [from Instrument instr order by name]
        at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:138) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:725) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:113) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.springframework.batch.item.database.HibernateItemReaderHelper.createQuery(HibernateItemReaderHelper.java:165) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.database.HibernateItemReaderHelper.getForwardOnlyCursor(HibernateItemReaderHelper.java:123) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.database.HibernateCursorItemReader.doOpen(HibernateCursorItemReader.java:187) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:150) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        ... 31 more
    Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: Instrument is not mapped [from Instrument instr order by name]
        at org.hibernate.hql.internal.ast.QuerySyntaxException.generateQueryException(QuerySyntaxException.java:79) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.QueryException.wrapWithQueryString(QueryException.java:103) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:220) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:144) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:113) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:73) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:155) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:604) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:716) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:113) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.springframework.batch.item.database.HibernateItemReaderHelper.createQuery(HibernateItemReaderHelper.java:165) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.database.HibernateItemReaderHelper.getForwardOnlyCursor(HibernateItemReaderHelper.java:123) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.database.HibernateCursorItemReader.doOpen(HibernateCursorItemReader.java:187) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:150) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        ... 31 more
    Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: Instrument is not mapped
        at org.hibernate.hql.internal.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:169) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:91) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.ast.tree.FromClause.addFromElement(FromClause.java:79) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:331) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3704) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3593) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:724) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:580) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:317) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:265) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:272) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:192) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:144) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:113) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:73) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:155) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:604) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:716) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:113) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
        at org.springframework.batch.item.database.HibernateItemReaderHelper.createQuery(HibernateItemReaderHelper.java:165) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.database.HibernateItemReaderHelper.getForwardOnlyCursor(HibernateItemReaderHelper.java:123) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.database.HibernateCursorItemReader.doOpen(HibernateCursorItemReader.java:187) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:150) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
        ... 31 more

Answer 1

The solution is to use the annotation @EntityScan("path_to_entities"). Now the entities are found and the object MetamodelImpl is populated correctly.