Cascading problem?

krosan · **Joined:** Fri Sep 10, 2010 5:00 am **Posts:** 7

Hey guys, I'm using hibernate on my project, and I've got a parent class & child class in a onetoone relationship, with the parent having a cascade=ALL to the child. When I'm persisting the parent, I see that the db is queried for the child (to see if it already exists, which it doesn't, the table is empty), and right after hibernate tries to insert the parent before the child, thus giving a FK constraint error. Do you know anything about this?

Code:

@Entity
@Table(name = "LANOMAL")
public class LAnomal extends Throwable implements java.io.Serializable {

[...]

   @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
   @PrimaryKeyJoinColumn
   public LStacktrace getStacktraceString() {
      return stacktraceString;
   }

}

@Entity
@Table(name = "LSTACKTRACE")
public class LStacktrace implements java.io.Serializable {

[...]

   @OneToOne(fetch = FetchType.LAZY, mappedBy = LAnomal.PROP_LSTACKTRACE)
   public LAnomal getException() {
      return this.exception;
   }

}

Quote:

INFO: Hibernate: select lanomal0_.DTCREAT as DTCREAT29_1_, lanomal0_.ADAMID as ADAMID29_1_, [...] from LANOMAL lanomal0_ left outer join LSTACKTRACE lstacktrac1_ on lanomal0_.DTCREAT=lstacktrac1_.DTCREAT where lanomal0_.DTCREAT=?
INFO: Hibernate: select lstacktrac0_.DTCREAT as DTCREAT49_0_, lstacktrac0_.CKEEP as CKEEP49_0_, [...] from LSTACKTRACE lstacktrac0_ where lstacktrac0_.DTCREAT=?
INFO: Hibernate: insert into LANOMAL (ADAMID, ANOMAL, CKEEP, DARCH, NOMCLASSE, CORELID, SLEUTEL, MSGID, METHODE, DTWIJZ, module, PACKAGE, RECRC, CTRAIT, USERID, DTCREAT) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)

WARNING: 14578 [SimpleAsyncTaskExecutor-33] WARN org.hibernate.util.JDBCExceptionReporter - SQL Error: -530, SQLState: 23503

WARNING: 14578 [SimpleAsyncTaskExecutor-33] ERROR org.hibernate.util.JDBCExceptionReporter - DB2 SQL error: SQLCODE: -530, SQLSTATE: 23503, SQLERRMC: EVAADM.LANOMAL.FKLANOMAL

Any help would be greatly appreciated!

krosan · **Joined:** Fri Sep 10, 2010 5:00 am **Posts:** 7

*bump*

Could anyone take a look at this please? It would greatly help me along.

Thanks in advance!

krosan · **Joined:** Fri Sep 10, 2010 5:00 am **Posts:** 7

Anyone who knows this issue?

nordborg · **Posted:** Tue Sep 14, 2010 7:11 am

Quote:

and right after hibernate tries to insert the parent before the child, thus giving a FK constraint error.

I have not looked into the details but the parent *should* be inserted before the child, so either you should change the foreign key definition in the database or you should switch the parent/child relationship around on your mappings.

krosan · **Joined:** Fri Sep 10, 2010 5:00 am **Posts:** 7

nordborg wrote:

Quote:

and right after hibernate tries to insert the parent before the child, thus giving a FK constraint error.

I have not looked into the details but the parent *should* be inserted before the child, so either you should change the foreign key definition in the database or you should switch the parent/child relationship around on your mappings.

But how can you insert the parent before the child if it has a reference to the child? The child won't exist yet in the database, and the reference to the child in the parent will be null.

Is the child the one who has a reference to the parent then?

nordborg · **Posted:** Tue Sep 14, 2010 7:51 am

Quote:

Is the child the one who has a reference to the parent then?

Yes! Just as in the real world a child can't exist without a parent. In a one-to-one relation it is not so obvious which one is the parent and which one is the child. Usually both hold references to each other. I am not so familiar with annotations but when using hbm.xml mapping files you simply put constrained="true" on the "child" side to indicate that there is a foreign key constraint and that the other side should be inserted first. I think the mappedBy attribute has a similar function.

krosan · **Joined:** Fri Sep 10, 2010 5:00 am **Posts:** 7

nordborg wrote:

Quote:

Is the child the one who has a reference to the parent then?

Yes! Just as in the real world a child can't exist without a parent. In a one-to-one relation it is not so obvious which one is the parent and which one is the child. Usually both hold references to each other. I am not so familiar with annotations but when using hbm.xml mapping files you simply put constrained="true" on the "child" side to indicate that there is a foreign key constraint and that the other side should be inserted first. I think the mappedBy attribute has a similar function.

Ah okey!

If you look at my code snippet I pasted in my original post, then I assume I need to put constrained=true on the getStackTraceString() method of the Anomal class?

shynate26 · **Posted:** Tue Sep 14, 2010 8:26 am

HI Krosan,

This can be resolved in simple object oriented concept.

Say u are creating one parent & One child.
now problem is that child reference does not have any value. It can resolve using,

parent.setChildReference(Child);
now, child.setParentReference(this);

class Parent{

Child childObj;

public void setChildObj(Child child){
this.childObj=child;
this.childObj.setParentObj(this);
}
}

krosan · **Joined:** Fri Sep 10, 2010 5:00 am **Posts:** 7

Hey, thanks for the reply.

I think I've got what you propose already implemented. I didn't paste the entire classes in my initial post, so I'll link you a pastebin with both classes:

LAnomal.java: http://pastebin.com/yW3CkVkL
LStacktrace.java: http://pastebin.com/g7iv9pGr

shynate26 · **Posted:** Tue Sep 14, 2010 8:50 am

Could you post your service layer snippet.

krosan · **Joined:** Fri Sep 10, 2010 5:00 am **Posts:** 7

shynate26 wrote:

Could you post your service layer snippet.

Here you go: http://pastebin.com/XPsSu0r8