Question

我正在尝试在 openJpa 2.3.0 中创建单向OneToMany映射，但我还想要定义将在源表上保存foreighn键的列名。据我所知，在JPA 2.0中，可以按如下方式完成：

@Entity
public class Source {


    private List<Target> targets = new ArrayList<>();


    @OneToMany
    @JoinColumn(name="SOURCE_FK")
    public List<Target> getTargets() {
        return targets;
    }
}

但我得到以下例外：

 <openjpa-2.3.0-r422266:1540826 fatal user error> org.apache.openjpa.persistence.ArgumentException: You have supplied columns for "Source.targets", but this mapping cannot have columns in this context.
at org.apache.openjpa.jdbc.meta.MappingInfo.assertNoSchemaComponents(MappingInfo.java:382)
at org.apache.openjpa.jdbc.meta.strats.RelationToManyTableFieldStrategy.map(RelationToManyTableFieldStrategy.java:97)
at org.apache.openjpa.jdbc.meta.strats.RelationCollectionTableFieldStrategy.map(RelationCollectionTableFieldStrategy.java:94)
at org.apache.openjpa.jdbc.meta.FieldMapping.setStrategy(FieldMapping.java:146)
at org.apache.openjpa.jdbc.meta.RuntimeStrategyInstaller.installStrategy(RuntimeStrategyInstaller.java:82)
at org.apache.openjpa.jdbc.meta.FieldMapping.resolveMapping(FieldMapping.java:496)
at org.apache.openjpa.jdbc.meta.FieldMapping.resolve(FieldMapping.java:461)
at org.apache.openjpa.jdbc.meta.ClassMapping.resolveMapping(ClassMapping.java:854)
at org.apache.openjpa.meta.ClassMetaData.resolve(ClassMetaData.java:1811)
at org.apache.openjpa.meta.MetaDataRepository.processBuffer(MetaDataRepository.java:829)
at org.apache.openjpa.meta.MetaDataRepository.resolveMapping(MetaDataRepository.java:784)
at org.apache.openjpa.meta.MetaDataRepository.resolve(MetaDataRepository.java:664)
at org.apache.openjpa.meta.MetaDataRepository.getMetaDataInternal(MetaDataRepository.java:418)
at org.apache.openjpa.meta.MetaDataRepository.getMetaData(MetaDataRepository.java:389)
at org.apache.openjpa.kernel.BrokerImpl.persistInternal(BrokerImpl.java:2666)
at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2604)
at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2587)
at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2491)
at org.apache.openjpa.kernel.DelegatingBroker.persist(DelegatingBroker.java:1077)
at org.apache.openjpa.persistence.EntityManagerImpl.persist(EntityManagerImpl.java:716)
at

似乎openJpa 2.3.0不支持单向oneToMany中的Joincolumn。这是真的还是我错过了什么？如果是这种情况，是否有不使用连接表的解决方法？

Answer 1

回答我自己的问题： OpenJpa 2在OneToMany关系中支持@JoinColumn。

正如我发现here，有各种原因导致此异常。

在我的例子中，问题是persistence.xml中的错误模式URL

有问题的一行是以下一行：

 xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">

这告诉OpenJpa遵守JPA 1.0规范（JPA 1.0不支持OneToMany关系中的此注释，但JPA 2确实如此）我将版本更改为2.0并且工作正常。

xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd" version="2.0">

在openJpa 2中没有joinTable的单向@oneToMany

1 个答案: