保存一对多 JPA 时出错，违反主键约束

Question

我在产品和功能之间有双向关系，用户将添加具有某些功能的产品并需要将它们保存在同一个事务中。 更新时，我需要删除所有旧功能并保存新添加的功能（如果有）

@Entity
@Table(name = "product")
public class Product{

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "mySeq")
    @SequenceGenerator(name = "mySeq")
    private Long id;


    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "product_id")
    private List<Feature> features = new ArrayList<Feature>();

    ...

    public Product addFeatures(Feature feature) {
        this.features.add(feature);
        feature.setProduct(this);
        return this;
    }
}

@Entity
@Table(name = "feature")
public class Feature{

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "mySeq")
    @SequenceGenerator(name = "mySeq")
    private Long id;


    @ManyToOne
    @JoinColumn(name="product_id")
    @JsonIgnoreProperties("features")
    private Product product;

    ...
}

下面是服务

@Service
@Transactional
public class ProductService {
    ...
    public ProductDTO addNew(ProductDTO productDTO){
        Product product = productMapper.toEntity(productDTO);
        product.getFeatures().clear();
        for(FeatureDTO featureDTO : productDTO.getFeatures()){
            Feature feature = featureMapper.toEntity(featureDTO);
            product.addFeatures(feature);

        }
        entityManager.persist(product);
        ...
    }


    public ProductDTO update(ProductDTO productDTO){
        Product product = productMapper.toEntity(productDTO);
        //Need to delete all old features and save the newly added
        featureRepository.deleteByProductId(productDTO.getId());
        product.getFeatures().clear();
        for(FeatureDTO featureDTO : productDTO.getFeatures()){
            Feature feature = featureMapper.toEntity(featureDTO);
            product.addFeatures(feature);
        }
        featureRepository.save(product);
        ...
    }

}

但是当我尝试添加新产品或更新它时，偶尔会出现以下错误（有时工作正常！）

org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:257)
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:223)
    at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:540)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:746)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:714)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:532)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:304)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)

...
Caused by: org.hibernate.exception.ConstraintViolationException: could not execute statement
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:112)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:178)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3032)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3547)
    at org.hibernate.action.internal.EntityInsertAction.execute(EntityInsertAction.java:89)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:600)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:474)
    at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:337)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39)
    at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1437)
    at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:494)
    at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3245)
    at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2451)
    at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:473)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:156)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$100(JdbcResourceLocalTransactionCoordinatorImpl.java:38)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:231)
    at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:68)
    at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:536)
    ... 120 common frames omitted
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: Violation of PRIMARY KEY constraint 'PK_FEATURE'. Cannot insert duplicate key in object 'dbo.feature'. The duplicate key value is (1451).
    at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:254)
    at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(SQLServerStatement.java:1608)
    at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.doExecutePreparedStatement(SQLServerPreparedStatement.java:578)
    at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement$PrepStmtExecCmd.doExecute(SQLServerPreparedStatement.java:508)
    at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:7240)

Answer 1

这里可能存在多个问题。

首先，您在两个实体上使用相同的@SequenceGenerator(name = "mySeq") 。 这些生成器具有全局 scope，它们不限于定义它们的 class。 实际上，我很惊讶您没有收到错误，因为您定义了两次具有相同名称的生成器。 但是您肯定对两个实体使用相同的生成器。

然后，我强烈建议您为@OneToMany设置 mapped_by 值，因为这是派生映射。 Hibernate 有一些默认的启发式方法来解决这个问题，但它并不总是你认为的那样。

第三，如果您确实要删除旧功能并在每次产品更新时重新创建它们，那么您的示例中缺少此代码。 这也可能是错误的来源，当您认为您删除了一个实体，但它实际上仍然存在，然后您尝试创建一个具有相同 ID 的新实体。

最后，我还将在@OneToMany 上设置一个明确的级联策略，以使其更加明显。

Answer 2

如果您希望能够通过父实体集合保留子实体，则需要设置 orphanRemoval=true 而不是调用clear()您可以执行setFeatures(null)然后setFeatures(productDTO.getFeatures())

但是，我建议您重写逻辑，以便直接通过 EntityManager 删除或更新您的功能。 您可以将传入特征的 id 与现有特征进行比较，然后删除不匹配的特征并创建没有 id 的特征并更新具有的特征。