Hibernate Community • View topic - ManyToOne and Delete

View unanswered posts | View active topics

Board index » Hibernate & Java Persistence » Hibernate Users

All times are UTC - 5 hours [ DST ]

ManyToOne and Delete

Page 1 of 1

[ 3 posts ]

Previous topic | Next topic

Author

Message

SirWayne

Post subject: ManyToOne and Delete

Posted: Sun Jan 10, 2010 9:49 am

Beginner

Joined: Mon Dec 29, 2008 3:25 pm
Posts: 20

Hello,
i have to classes A und B they have a ManyToOne dependency . If i delete A , all b objects should be delete too. How can I do this?

Code:

public class B{

   @ManyToOne(cascade = {CascadeType.ALL})
   @Override
   public A getA() {
      return a;
   }
   @Override
   public void setA(Aa) {
   this.a= a;
   }
}

But I gett follow exception

Code:

Caused by: org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
   at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:94)
   at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
   at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
   at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:266)
   at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:172)
   at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
   at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:50)
   at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1027)
   at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:365)
   at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:137)
   at org.springframework.orm.hibernate3.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:656)
   ... 42 more
Caused by: java.sql.BatchUpdateException: Cannot delete or update a parent row: a foreign key constraint fails (`verwaltung`.`b`, CONSTRAINT `FK951BD2B13A9AD6FA` FOREIGN KEY (`a_id`) REFERENCES `a` (`id`))
   at com.mysql.jdbc.PreparedStatement.executeBatchSerially(PreparedStatement.java:2007)
   at com.mysql.jdbc.PreparedStatement.executeBatch(PreparedStatement.java:1443)
   at org.apache.commons.dbcp.DelegatingStatement.executeBatch(DelegatingStatement.java:297)
   at org.apache.commons.dbcp.DelegatingStatement.executeBatch(DelegatingStatement.java:297)
   at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
   at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
   ... 50 more

Top

PradeepKumar

Post subject: Re: ManyToOne and Delete

Posted: Sun Jan 10, 2010 12:06 pm

Newbie

Joined: Fri Jan 08, 2010 5:12 am
Posts: 4

Its because you are trying to violate the foreign key constraint. You need to delete the the child instance and then delete the parent. Alternatively you can use the cascade delete orphan option to delete the entire object graph of parent and child without deleting the child individually. But in case the child instances are referenced by other entities then you have no other option other than navigating the object graph and removing the references manually before deleting the instance. So try with the cascade delete orphan option first and then see if u are still getting an exception dig to the code. Hope this helps you :-)

Top

kravicha

Post subject: Re: ManyToOne and Delete

Posted: Mon Jan 11, 2010 10:59 am

Newbie

Joined: Tue Jun 02, 2009 4:06 am
Posts: 16

Hi,

In your above example, B is the parent and A is the child.Hence if you delete A then B wont get deleted because theree might be another instances of A refering to B.Hence it throwns COntraint viiolation.

When ayou use a cascade-delete in that case when you delete a parent then all the child referncing to parent will be deleted.In your case if B is deleted then all A referring to B will be deleted but vice versa isnt possible.

Now in case of orphan-delet,it will delete all the child which doesnt have a parent.Fro example in your case if your delete an instance of B then all the instance/row of A referncing B will be deleted along with that all the instances of A which doesnt refer to B will also be deleted.
So this option also wont work.

Conclusion you cant delete B by just deleting A.

Hope it helps

Kartik

Top

Page 1 of 1

[ 3 posts ]

Board index » Hibernate & Java Persistence » Hibernate Users

All times are UTC - 5 hours [ DST ]

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum