休止状態で1対1の関係を使用して削除

Question

私は休止状態にしていないので、休止状態4を使用しています。次のコードには、アノテーションを使用した1対1の関係の簡単な例が含まれています。親オブジェクトを削除しようとすると、外部キー制約の例外がスローされます。私は固執してこれを達成する方法を混乱させる。私はカスケード型をすべて使用していますが間違いを修正する

これは、データベースに挿入して更新するために使用される親クラスです。

import javax.persistence.CascadeType; 
import javax.persistence.Entity; 
import javax.persistence.Column; 
import javax.persistence.FetchType; 
import javax.persistence.JoinColumn; 
import javax.persistence.OneToOne; 
import javax.persistence.Id; 
import javax.persistence.Table; 


    @Entity 
    @Table(name="address") 

public class Address { 
@Id 
@Column(name="address_id") 
private long addressId=0; 

@Column(name="place",length=30) 
private String place=null; 

@OneToOne(targetEntity=Student.class,fetch=FetchType.EAGER , cascade=CascadeType.ALL, orphanRemoval=true) 
@JoinColumn(name="stud_id",referencedColumnName="student_id") 

private Student parent; 

public long getAddressId() { 
    return addressId; 
} 

public void setAddressId(long addressId) { 
    this.addressId = addressId; 
} 

public String getPlace() { 
    return place; 
} 

public void setPlace(String place) { 
    this.place = place; 
} 

public Student getParent() { 
    return parent; 
} 

public void setParent(Student parent) { 
    this.parent = parent; 
} 
} 

次に、オブジェクトを削除する方法を示します。しかし、私は例外を取得しています。どのように親オブジェクトに関連付けられている子レコードを削除する？

public void deleteStudentDao(long studentId) throws Exception{ 
    Session session=null; 
    try{ 

     if(studentId >0 && factory!=null 
       && !factory.isClosed()){ 
      session=factory.openSession(); 
      session.beginTransaction(); 

      Student student=new Student(); 
      student.setStudentId(studentId); 

      Address address=new Address(); 
      address.setParent(student); 

      session.delete(address); 
      session.getTransaction().commit(); 
      System.out.println("The Student "+studentId+" detail deleted"); 
     } 
    }catch(HibernateException e){ 
     session.getTransaction().rollback(); 
     throw e; 
    }finally{ 
     if(session!=null){ 
      session.close(); 
     } 
    } 
} 

例外は、あなたがそのようなアドレスdeleteいけない

ERROR: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`address`, CONSTRAINT `FK_4ok3rcn3mnfl5ma2wuwvkluuo` FOREIGN KEY (`stud_id`) REFERENCES `students` (`student_id`)) 
    Mar 10, 2017 10:50:34 AM org.hibernate.engine.jdbc.batch.internal.AbstractBatchImpl release 
    INFO: HHH000010: On release of batch it still contained JDBC statements 
    org.hibernate.exception.ConstraintViolationException: could not execute statement 
     at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:72) 
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) 
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126) 
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112) 
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:211) 
    at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:62) 
    at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3400) 
    at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3630) 
    at org.hibernate.action.internal.EntityDeleteAction.execute(EntityDeleteAction.java:114) 
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:463) 
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:349) 
    at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:350) 
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:56) 
    at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1222) 
    at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:425) 
    at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101) 
    at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:177) 
    at com.mv.dao.StudentDetailDAO.deleteStudentDao(StudentDetailDAO.java:98) 
    at com.mv.studentutil.StudentRelationalUtil.deleteStudentUtil(StudentRelationalUtil.java:56) 
    at com.mv.studentmodifier.StudentModifier.main(StudentModifier.java:54) 
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`address`, CONSTRAINT `FK_4ok3rcn3mnfl5ma2wuwvkluuo` FOREIGN KEY (`stud_id`) REFERENCES `students` (`student_id`)) 
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) 
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) 
    at java.lang.reflect.Constructor.newInstance(Unknown Source) 
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:408) 
    at com.mysql.jdbc.Util.getInstance(Util.java:383) 
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1049) 
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4226) 
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4158) 
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2615) 
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2776) 
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2840) 
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2082) 
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2334) 
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2262) 
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2246) 
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208) 
    ... 15 more 

Answer 1

です。あなたの場合、学生&住所の間に双方向の関係が必要です。

@Entity 
@Table(name = "students")  
public class Student { 
    ...  
    // Add this property with getter & setter methods in your Student class. 
    @OneToOne(mappedBy="parent") 
    private Address address; 

    ... 

} 

削除メソッドでは、IDからDBからStudentエンティティを取得し、生徒エンティティから学生アドレスを取得して、アドレスエンティティを削除します。これはカスケード性のために住所と生徒を削除します。

try { 

      if (studentId > 0 && factory != null && !factory.isClosed()) { 
       session = factory.openSession(); 
       session.beginTransaction(); 

       Student student = (Student) session.get(Student.class, studentId); 
       session.delete(student.getAddress()); 

       /*Student student=new Student(); 
       student.setStudentId(studentId); 

       Address address=new Address(); 
       address.setParent(student); 

       session.delete(address);*/ 

       session.getTransaction().commit(); 
       System.out.println("The Student " + studentId + " detail deleted"); 
      }