Question

我尝试在hibernate 4.3.1.Final的实体中保留@ElementCollection。该实体看起来像这样：

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正确生成架构：

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);

Generated schema

但是当我将CompositeKey更改为引用另一个Entity时，当hibernate在启动时生成元模型时，我得到QueryException。

更改后的代码：

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

引用的Entity：

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

例外：

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]
    ...

我的地图有什么问题？如何防止此异常？

有趣的是，BasicCollectionPersister似乎已正确初始化。调试显示，例如sqlUpdateRowString为update MyEntity_map set val1=?, val2=? where MyEntity_id=? and key1_id=? and key2=?。

Answer 1

从JPA 2.0规范：

不支持嵌入式id类中定义的关系映射。

另见JPA - EmbeddedId with @ManytoOne。

修改

Hibernate 4.3.1.Final实现了JPA 2.1，所以我的第一个猜测错了。 Mea culpa。

映射问题是@ElementCollection使用嵌入CompositeKey引用实体ReferencedEntity。当Hibernate查找AbstractPropertyMapping（sic！）到CompositeValue的引用时，抛出ReferencedEntity中的异常。但是，由于不存在这样的关系，因此抛出异常。对我来说，目前还不清楚这是一个Hibernate错误还是根据JPA 2.1规范。

我看到以下解决方案。

解决方案1 

将CompositeKey更改为Entity添加id字段。在这种情况下，可以使用@OneToMany注释：

@Entity public class CompositeKey { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Integer id; @ManyToOne(targetEntity = ReferencedEntity.class) private ReferencedEntity key1; @Basic private Integer key2; }

解决方案2

添加其他实体CompositeSampler，其中包含CompositeKey作为ID，CompositeValue作为附加属性。 MyEntity将包含CompositeSampler的列表。

解决方案3

将CompositeValue的引用添加到ReferencedEntity。

顺便说一下，根据JPA 2.1规范：“如果使用嵌入类作为映射键，则嵌入类必须实现hashCode，并且将方法与嵌入映射到的数据库列一致”。

Hibernate / JPA：当hibernate为@ElementCollection生成元模型时，QueryException

1 个答案: