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java - 使用 JPA 从 child 获取 parent

转载 作者：行者123 更新时间：2023-12-01 15:06:51 25 4
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我有一个电话对象和一个电话历史记录对象。我希望能够检索电话历史记录对象，然后获取其父对象(电话)，但由于某种原因，当我尝试执行此操作然后保留子对象时，我收到一个异常，提示电话 ID 未填充。不知道如何解决这个问题，尽管我怀疑它与我的映射注释有关。

下面是我的实体类。我尝试更改注释以匹配双向关系部分中的建议:http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html/entity.html#entity-mapping-association但这似乎并没有起到作用。我是 JPA 的新手，所以这对于有更多经验的人来说可能很简单，但我很困惑。 TIA。

电话实体:

package com.blah.model;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

@Entity
@Table(name = "phones")
public class EPhone implements BaseModel {

    private static final long serialVersionUID = 3497994786207995664L;

    @Id
    @GeneratedValue
    @Column(name = "id")
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "account_id",
            nullable = false)
    private EAccount account;

    @Temporal(TemporalType.TIMESTAMP)
    private Calendar created;

    @Column(name = "value",
        nullable = false)
        private Long value;

    @OneToMany(fetch = FetchType.LAZY,
            mappedBy = "phone",
            cascade = CascadeType.ALL)
    private final List<EPhoneHistory> history;

    public EPhone() {
        this(Calendar.getInstance());
    }

    public EPhone(final Calendar createdDate) {
        setCreated(createdDate);
        history = new ArrayList<EPhoneHistory>();
    }

    public void add(EPhoneHistory phoneHistoryItem) {
        history.add(phoneHistoryItem);
    }

    public EAccount getAccount() {
        return account;
    }

    public Calendar getCreated() {
        return created;
    }

    @OneToMany(fetch = FetchType.LAZY,
            mappedBy = "phone",
            cascade = CascadeType.ALL)
    public List<EPhoneHistory> getHistory() {
        return history;
    }

    public Long getId() {
        return id;
    }

    public Long getValue() {
        return value;
    }

    public void setAccount(EAccount account) {
        this.account = account;
    }

    public void setCreated(Calendar created) {
        this.created = created;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public void setValue(Long value) {
        this.value = value;
    }

}

电话历史记录实体:

package com.blah.model;

import java.util.Calendar;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EnumType;
import javax.persistence.Enumerated;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

@Entity
@Table(name = "phone_history")
public class EPhoneHistory implements BaseModel {

    private static final long serialVersionUID = 4591314258588732076L;

    @Id
    @GeneratedValue
    @Column(name = "id")
    private Long Id;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "phone_id",
            nullable = false)
    private EPhone phone;

    @Temporal(TemporalType.TIMESTAMP)
    private Calendar created;

    @Enumerated(EnumType.ORDINAL)
    @Column(name = "type_id")
    private PhoneHistoryType type;

    public Calendar getCreated() {
        return created;
    }

    public Long getId() {
        return Id;
    }

    public EPhone getPhone() {
        return phone;
    }

    public PhoneHistoryType getType() {
        return type;
    }

    public void setCreated(Calendar created) {
        this.created = created;
    }

    public void setId(Long id) {
        Id = id;
    }

    public void setPhone(EPhone phone) {
        this.phone = phone;
    }

    public void setType(PhoneHistoryType type) {
        this.type = type;
    }

}

更新澄清(这是一个失败的测试):

package com.blah.model.repository;

import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.annotation.Transactional;

import com.blah.AbstractBaseDbTestCase;
import com.blah.model.EPhoneHistory;
import com.blah.model.PhoneHistoryType;

public class PhoneHistoryRepositoryTest extends AbstractBaseDbTestCase {

    @Autowired
    PhoneHistoryRepository phoneHistoryRepo;

    @Test
    @Transactional
    public void testCreateAndSavePhoneHistory() {

        EPhoneHistory existingPhoneHistory = phoneHistoryRepo.find(1L);

        EPhoneHistory newPhoneHistory = new EPhoneHistory();
        newPhoneHistory.setType(PhoneHistoryType.VOICE);

        // I assume this is where I would
        // set the phone, but I don't have it.
        // existingPhoneHistory.setPhone(phone);

        // This is what I'm having trouble with. getPhone() doesn't populate the
        // phone field with the parent phone object.
        existingPhoneHistory.getPhone().add(newPhoneHistory);

        phoneHistoryRepo.persist(existingPhoneHistory);
        phoneHistoryRepo.flush();
    }
}

以及失败堆栈跟踪:

org.springframework.dao.DataIntegrityViolationException: NULL not allowed for column "PHONE_ID"; SQL statement:
insert into phone_history (id, created, phone_id, type_id) values (null, ?, ?, ?) [23502-168]; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: NULL not allowed for column "PHONE_ID"; SQL statement:
insert into phone_history (id, created, phone_id, type_id) values (null, ?, ?, ?) [23502-168]
    at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:643)
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:104)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:403)
    at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:58)
    at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:163)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622)
    at com.blah.model.repository.PhoneHistoryRepository$$EnhancerByCGLIB$$4f90cdde.flush(<generated>)
    at com.blah.model.repository.PhoneHistoryRepositoryTest.testCreateAndSavePhoneHistory(PhoneHistoryRepositoryTest.java:29)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: org.hibernate.exception.ConstraintViolationException: NULL not allowed for column "PHONE_ID"; SQL statement:
insert into phone_history (id, created, phone_id, type_id) values (null, ?, ?, ?) [23502-168]
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:128)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
    at org.hibernate.engine.jdbc.internal.proxy.AbstractStatementProxyHandler.continueInvocation(AbstractStatementProxyHandler.java:129)
    at org.hibernate.engine.jdbc.internal.proxy.AbstractProxyHandler.invoke(AbstractProxyHandler.java:81)
    at $Proxy37.executeUpdate(Unknown Source)
    at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:96)
    at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:58)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2870)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3381)
    at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:81)
    at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:362)
    at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:203)
    at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:183)
    at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:167)
    at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:320)
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:287)
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:126)
    at org.hibernate.ejb.event.EJB3PersistEventListener.saveWithGeneratedId(EJB3PersistEventListener.java:78)
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:208)
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:151)
    at org.hibernate.internal.SessionImpl.firePersistOnFlush(SessionImpl.java:870)
    at org.hibernate.internal.SessionImpl.persistOnFlush(SessionImpl.java:863)
    at org.hibernate.engine.spi.CascadingAction$8.cascade(CascadingAction.java:346)
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:380)
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:323)
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
    at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:409)
    at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:350)
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:326)
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:165)
    at org.hibernate.event.internal.AbstractFlushingEventListener.cascadeOnFlush(AbstractFlushingEventListener.java:160)
    at org.hibernate.event.internal.AbstractFlushingEventListener.prepareEntityFlushes(AbstractFlushingEventListener.java:151)
    at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:88)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
    at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1214)
    at org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:986)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:240)
    at $Proxy32.flush(Unknown Source)
    at com.blah.model.repository.AbstractRepository.flush(AbstractRepository.java:41)
    at com.blah.model.repository.AbstractRepository$$FastClassByCGLIB$$1ba8d45c.invoke(<generated>)
    at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
    at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:689)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:155)
    ... 36 more
Caused by: org.h2.jdbc.JdbcSQLException: NULL not allowed for column "PHONE_ID"; SQL statement:
insert into phone_history (id, created, phone_id, type_id) values (null, ?, ?, ?) [23502-168]
    at org.h2.message.DbException.getJdbcSQLException(DbException.java:329)
    at org.h2.message.DbException.get(DbException.java:169)
    at org.h2.message.DbException.get(DbException.java:146)
    at org.h2.table.Column.validateConvertUpdateSequence(Column.java:293)
    at org.h2.table.Table.validateConvertUpdateSequence(Table.java:689)
    at org.h2.command.dml.Insert.insertRows(Insert.java:120)
    at org.h2.command.dml.Insert.update(Insert.java:84)
    at org.h2.command.CommandContainer.update(CommandContainer.java:75)
    at org.h2.command.Command.executeUpdate(Command.java:230)
    at org.h2.jdbc.JdbcPreparedStatement.executeUpdateInternal(JdbcPreparedStatement.java:156)
    at org.h2.jdbc.JdbcPreparedStatement.executeUpdate(JdbcPreparedStatement.java:142)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.hibernate.engine.jdbc.internal.proxy.AbstractStatementProxyHandler.continueInvocation(AbstractStatementProxyHandler.java:122)
    ... 83 more

最佳答案

由于您进行了惰性连接，我怀疑您没有在子对象phoneHistory中填充父对象phone。请验证(通过phoneHistory调试/打印电话对象值)。如果是这样，请先在 phoneHistory 中设置 phone 对象，然后再保存。

在Phone对象中添加方法addPhoneHistory，如下所示:

      public void addPhoneHistory(PhoneHistory phoneHistory){
         phoneHistory.setPhone(this); //This is importtant as its sets the parent
         if(this.phoneHistories == null){
            this.phoneHistories = new ArrayList<PhoneHistory>();
         } 
         this.phoneHistories.add(phoneHistory); 
      }

在代码中添加一行，以便在 Phone 对象中添加 PhoneHistory 对象以使用上述方法。

    existingPhoneHistory.getPhone().addPhoneHistory(newPhoneHistory);

另外，保存“电话代替现有电话历史记录”也是个好主意，如下所示:

   Phone phone = existingPhoneHistory.getPhone();
   phone.addPhoneHistory(newPhoneHistory);
   entityManager.save(phone);//use your PhoneRepo, if there to persist

希望这有帮助。

关于java - 使用 JPA 从 child 获取 parent ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12850986/

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