Hibernate / JPA: QueryException when hibernate generates metamodel for @ElementCollection

Question

I try to persist an @ElementCollection within an entity with hibernate 4.3.1.Final. The entity looks like this:

import javax.persistence.*;
import java.util.Map;
@Entity
public class MyEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
    @ElementCollection
    private Map<CompositeKey, CompositeValue> map;

    @Embeddable
    public static class CompositeKey {
        @Basic
        private Integer key1;
        @Basic
        private Integer key2;
    }

    @Embeddable
    public static class CompositeValue {
        @Basic
        private Integer val1;
        @Basic
        private Integer val2;
    }
}

Hibernate generates the schema correctly:

create table MyEntity (id integer not null, primary key (id)) ENGINE=InnoDB;
create table MyEntity_map (MyEntity_id integer not null, val1 integer, val2 integer, key1 integer, key2 integer, primary key (MyEntity_id, key1, key2)) ENGINE=InnoDB;
create table ReferencedEntity (id integer not null, primary key (id)) ENGINE=InnoDB;
alter table MyEntity_map add constraint FK_mhu8q8dtieguddm0w4gxfwhnc foreign key (MyEntity_id) references MyEntity (id);

But when I change CompositeKey to reference another Entity , I get a QueryException when hibernate generates the metamodel on startup.

The changed code:

@Embeddable
public static class CompositeKey {
    @ManyToOne
    private ReferencedEntity key1;
    @Basic
    private Integer key2;
}

The referenced Entity :

import javax.persistence.*;
@Entity
public class ReferencedEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
}

The Exception:

Caused by: org.hibernate.QueryException: could not resolve property: key1 of: component[val1,val2]
    at org.hibernate.persister.entity.AbstractPropertyMapping.propertyException(AbstractPropertyMapping.java:83) ~[AbstractPropertyMapping.class:4.3.1.Final]
    at org.hibernate.persister.entity.AbstractPropertyMapping.toColumns(AbstractPropertyMapping.java:98) ~[AbstractPropertyMapping.class:4.3.1.Final]
    at org.hibernate.persister.collection.AbstractCollectionPersister.toColumns(AbstractCollectionPersister.java:1625) ~[AbstractCollectionPersister.class:4.3.1.Final]
    at org.hibernate.loader.plan.build.internal.spaces.CompositePropertyMapping.toColumns(CompositePropertyMapping.java:124) ~[CompositePropertyMapping.class:4.3.1.Final]
    at org.hibernate.loader.plan.build.internal.spaces.CompositeQuerySpaceImpl.toAliasedColumns(CompositeQuerySpaceImpl.java:52) ~[CompositeQuerySpaceImpl.class:4.3.1.Final]
    at org.hibernate.loader.plan.build.internal.spaces.JoinImpl.resolveAliasedLeftHandSideJoinConditionColumns(JoinImpl.java:79) ~[JoinImpl.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.LoadQueryJoinAndFetchProcessor.addJoins(LoadQueryJoinAndFetchProcessor.java:261) ~[LoadQueryJoinAndFetchProcessor.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.LoadQueryJoinAndFetchProcessor.renderEntityJoin(LoadQueryJoinAndFetchProcessor.java:193) ~[LoadQueryJoinAndFetchProcessor.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.LoadQueryJoinAndFetchProcessor.renderJoin(LoadQueryJoinAndFetchProcessor.java:158) ~[LoadQueryJoinAndFetchProcessor.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.LoadQueryJoinAndFetchProcessor.processQuerySpaceJoin(LoadQueryJoinAndFetchProcessor.java:137) ~[LoadQueryJoinAndFetchProcessor.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.LoadQueryJoinAndFetchProcessor.processQuerySpaceJoins(LoadQueryJoinAndFetchProcessor.java:132) ~[LoadQueryJoinAndFetchProcessor.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.LoadQueryJoinAndFetchProcessor.processQuerySpaceJoin(LoadQueryJoinAndFetchProcessor.java:138) ~[LoadQueryJoinAndFetchProcessor.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.LoadQueryJoinAndFetchProcessor.processQuerySpaceJoins(LoadQueryJoinAndFetchProcessor.java:132) ~[LoadQueryJoinAndFetchProcessor.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.LoadQueryJoinAndFetchProcessor.processQuerySpaceJoins(LoadQueryJoinAndFetchProcessor.java:113) ~[LoadQueryJoinAndFetchProcessor.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.AbstractLoadQueryDetails.generate(AbstractLoadQueryDetails.java:171) ~[AbstractLoadQueryDetails.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.BasicCollectionLoadQueryDetails.<init>(BasicCollectionLoadQueryDetails.java:60) ~[BasicCollectionLoadQueryDetails.class:4.3.1.Final]
    at org.hibernate.loader.plan.exec.internal.BatchingLoadQueryDetailsFactory.makeCollectionLoadQueryDetails(BatchingLoadQueryDetailsFactory.java:101) ~[BatchingLoadQueryDetailsFactory.class:4.3.1.Final]
    at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.<init>(AbstractLoadPlanBasedCollectionInitializer.java:77) ~[AbstractLoadPlanBasedCollectionInitializer.class:4.3.1.Final]
    at org.hibernate.loader.collection.plan.CollectionLoader.<init>(CollectionLoader.java:112) ~[CollectionLoader.class:4.3.1.Final]
    at org.hibernate.loader.collection.plan.CollectionLoader$Builder.byKey(CollectionLoader.java:105) ~[CollectionLoader$Builder.class:4.3.1.Final]
    at org.hibernate.loader.collection.plan.AbstractBatchingCollectionInitializerBuilder.buildNonBatchingLoader(AbstractBatchingCollectionInitializerBuilder.java:45) ~[AbstractBatchingCollectionInitializerBuilder.class:4.3.1.Final]
    at org.hibernate.loader.collection.BatchingCollectionInitializerBuilder.createBatchingCollectionInitializer(BatchingCollectionInitializerBuilder.java:71) ~[BatchingCollectionInitializerBuilder.class:4.3.1.Final]
    at org.hibernate.persister.collection.BasicCollectionPersister.createCollectionInitializer(BasicCollectionPersister.java:343) ~[BasicCollectionPersister.class:4.3.1.Final]
    at org.hibernate.persister.collection.AbstractCollectionPersister.postInstantiate(AbstractCollectionPersister.java:676) ~[AbstractCollectionPersister.class:4.3.1.Final]
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:484) ~[SessionFactoryImpl.class:4.3.1.Final]
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1857) ~[Configuration.class:4.3.1.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:850) ~[EntityManagerFactoryBuilderImpl$4.class:4.3.1.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:843) ~[EntityManagerFactoryBuilderImpl$4.class:4.3.1.Final]
    at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.withTccl(ClassLoaderServiceImpl.java:399) ~[ClassLoaderServiceImpl.class:4.3.1.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:842) ~[EntityManagerFactoryBuilderImpl.class:4.3.1.Final]
    at org.hibernate.jpa.HibernatePersistenceProvider.createContainerEntityManagerFactory(HibernatePersistenceProvider.java:150) ~[HibernatePersistenceProvider.class:4.3.1.Final]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:336) ~[LocalContainerEntityManagerFactoryBean.class:4.0.1.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:318) ~[AbstractEntityManagerFactoryBean.class:4.0.1.RELEASE]
    ...

What is wrong with my mapping? How can I prevent this exception?

It is interesting, that the BasicCollectionPersister seems to get initialized correctly. Debugging shows, that eg the sqlUpdateRowString is update MyEntity_map set val1=?, val2=? where MyEntity_id=? and key1_id=? and key2=? update MyEntity_map set val1=?, val2=? where MyEntity_id=? and key1_id=? and key2=? .

Answer 1

From the JPA 2.0 specification:

Relationship mappings defined within an embedded id class are not supported.

See also JPA - EmbeddedId with @ManytoOne .

EDIT:

Hibernate 4.3.1.Final implements JPA 2.1, so my first guess was wrong. Mea culpa.

The problem with the mapping is the use of @ElementCollection with an embeddable CompositeKey referencing to the entity ReferencedEntity . The exception in AbstractPropertyMapping is thrown when Hibernate looks for a reference from CompositeValue (sic!) to ReferencedEntity . However as no such relation exists, the exception is thrown. For me it is unclear if this is a Hibernate bug or according the JPA 2.1 specs.

I see following solutions.

Solution 1

Change CompositeKey to an Entity adding an id field. In this case the @OneToMany annotation could be used:

@Entity
public class CompositeKey {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @ManyToOne(targetEntity = ReferencedEntity.class)
    private ReferencedEntity key1;

    @Basic
    private Integer key2;

}

Solution 2

Add an additional entity CompositeSampler containing CompositeKey as the ID and CompositeValue as an additional attribute. MyEntity will contain a list of CompositeSampler .

Solution 3

Add a reference from CompositeValue to ReferencedEntity .

By the way, according the JPA 2.1 specs: "If an embeddable class is used as a map key, the embeddable class must implement the hashCode and equals methods consistently with the database columns to which the embeddable is mapped".